Table of Content

12 July 2007, Volume 33 Issue 07

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ORIGINAL PAPERS

Identification and Molecular Mapping of a Novel Stripe Rust Resistance Gene in a Triticum durum-Aegilops tauschii Amphiploid CI108

HE Ming-Zhao;WANG Li-Min;ZHANG Zeng-Yan;XU Shi-Chang;WANG Li-Li;XIN Zhi-Yong

Acta Agron Sin. 2007, 33(07):  1045-1050. 

Abstract ( 2041 )   PDF (7554KB) ( 1104 )   Save

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From 102 synthetic wheat germplasms of Triticum durum and Aegilops tauschii, a germplasm CI108 with combination of GAN/Ae. squarrosa 201 conferring good resistance to stripe rust, with infection type (IT) of 0 or 0; grade, was identified through inoculating Chinese prevailing races of Puccinia striformis f. sp. Tritici（Pst），including CY28–CY32, and Shuiyuan 11-4. The results of genetic analysis suggested the stripe rust resistance gene in CI108 was controlled by a single nuclear dominate gene, temporarily termed YrC108. The results of gene postulation, in which the responses of CI108 and 25 wheat lines possessing known stripe rust resistance genes were evaluated to 30 races of Pst showed that CI108 conferred resistance to all 30 races of Pst. The response pattern of CI108 to the 30 races was different from those of the 23 lines containing known resistance genes but similar to those of K733 containing Yr24 and Lovin 13 containing Yr9+unknown gene. However, the degree of resistance of CI108 was different from those of K733 and Lovrin 13. By using an F₂ population of CI108/Mingxian 169 and BSA method, SSR markers associated with YrC108 were screened. We identified three SSR markers: Xgwm456 and Wmc419 located on one side of YrC108 with a genetic distance of 0.6 cM and 1.8 cM respectively, whereas Wmc413 located on the other side of YrC108 with a genetic distance of 0.6 cM. Furthermore, the markers could distinguish YrC108 from the resistance genes in K733 and Lovrin 13, suggesting that YrC108 should be a novel resistance gene.

Proteomic Analysis of Rice Cultivar Jiafuzhan in the Responses to Xanthomonas campestris pv. oryzicola Infection

CHEN Fang-Yu;HUANG Qing-Yun;ZHANG Hong-Xin;LIN Tao;Guo Yu-Chun;LIN Wen-Xiong;CHEN Liang

Acta Agron Sin. 2007, 33(07):  1051-1058. 

Abstract ( 2055 )   PDF (4397KB) ( 1100 )   Save

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Rice bacterial leaf streak(BLS) caused by the pathogen Xanthomonas oryzae pv. oryzicola (Xooc) is one of the major rice diseases in South China. Here we focus on proteomics as a tool for the discovery of differentially expressed proteins closely related to the disease resistance. The leaves of rice cultivar Jiafuzhan (Oryzae sativa L.) highly resistant to the disease, were infected by “89773-1-1” strain of the Xooc with strong pathogenicity. Total proteins were extracted from the leaves sampled at two days after inoculation, and separated by two-dimensional electrophoresis. It was found that there were thirty-eight proteins expressed differentially, of which thirty-two were up-regulated, five down-regulated and one was “new”. Of the thirty-eight responsive proteins, thirty-three were identified by MALDI-TOF-MS and database searching. Based on the predicted function, we grouped them into four clusters: signal transduction, defensive responses, substance metabolism and protein stabilization, which were involved in many resistant physiological reactions, including signal recognition and transduction, antioxidant reaction, carbonhydrate metabolism, cell-wall reinforcement and phytoalexin biosythesis. In turn a complex signal transduction and metabolic regulative network in the resistant responses to the infection of Xooc was outlined in this work, and the molecular mechanism was revealed by differentially expressed protein /enzyme patterns during Xooc infection. In this study, eight R proteins and three pathogenesis-related(PR) proteins which might relate closely to the disease-resistance were found. This result provides us the basic information to further reveal the resistant mechanism and conduct functional cloning of the resistant-related genes in rice to BLS.

Development of Wheat Mutants Carrying Different Null Wx Alleles and Their Starch Properties

ZHAI Hong-Mei;TIAN Ji-Chun

Acta Agron Sin. 2007, 33(07):  1059-1066. 

Abstract ( 1895 )   PDF (4325KB) ( 1114 )   Save

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The mutation at Wx-A1, Wx-B1, and Wx-D1 alleles may cause lack of Wx-A1, Wx-B1, and Wx-D1 proteins, and influence obviously the wheat quality. We use a normal cultivar Gaocheng 8901 (carrying three Wx genes) and Waxy Wheat 1 (null at the three Wx alleles) to develop a population of recombinant inbred lines (RILs) through single-seed descent method. A total of 228 RIL (F₇) lines was obtained to study the agronomic traits and starch characteristics responsing to Wx allele mutation, among which 34 of wild types, 26 of Wx-A1 null, 32 of Wx-B1 null, 30 of Wx-D1 null, 28 of Wx-A1 and Wx-B1 null, 20 of Wx-A1 and Wx-D1 null, 28 of Wx-B1 and Wx-D1 null, and 16 of waxy lines with the three null alleles were examined by improved sodium dodecyl sulphate-polyacrylamide gel electrophoresis. The null allele at each Wx locus fits Mendelian segregation by chi-square test. Field experiments did not show significant differences (P>0.05) in the traits of initial blooming stage, plant height, and grain number per ear among the eight types, but the Wx-A1 null type was significantly lower (P<0.05) than other seven types in the traits of spike length, spikelet number per ear, and 1000-grain weight, while there were no significant differences among the seven types. The amylose content, starch pasting characteristics, and TPA characteristics of starch gels were all influenced significantly by different Wx protein deficiencies. The highest amylose content appeared in the wild type (20.8%), and the lowest in the waxy type (1.1%). The starch in waxy wheat has higher peak viscosity and breakdown, lower trough viscosity, final viscosity, and setback as compared with other types (P<0.05). With the decrease of amylose content, the hardness, adhesiveness, springiness, gumminess and chewiness of starch gels decreased, while cohesiveness, and resilience increased significantly in the eight types. The amylose content was positively correlated with trough viscosity, final viscosity, setback, peak time, and pasting temperature (r=0.892–0.965, P<0.01), but negatively correlated with peak viscosity, and breakdown (r=－0.892, r=－0.945, P<0.01). Test of starch gel characteristics showed that amylose content was negatively correlated with cohesiveness, and resilience (r=－0.928, r=－0.829, P<0.01), but positively correlated with hardness, adhesiveness, springiness, gumminess, and chewiness ( r=0.869~0.979, P<0.01).

Generation of Transgenic Potato Plants Harboring AtNHX1 Gene Mediated by Agrobacterium tumefaciens

ZHANG Jun-Lian;WANG Li;WANG Di;ZHANG Jin-Wen;CHEN Zheng-Hua

Acta Agron Sin. 2007, 33(07):  1067-1072. 

Abstract ( 2059 )   PDF (9127KB) ( 1086 )   Save

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Drought and soil salinization harm are a major challenges that compromise crops growth and lead to soil degeneration and desertification of natural environments. Most of food crops are glycophytes with high susceptibility or low tolerance to soil salinization. Development of new salt-tolerant crop varieties is important to production in large area of saline soils. It is known that the adaptation of plant cells to salt stress requires an improved cellular ion homeostasis that involves organic solute accumulation in cytosol, vacuolar compartmentalization of ions and exclusion of extra Na⁺ from the cells. The latter two functions are implemented by a Na⁺/H⁺ antiporter located on both plasma membrane and tonoplast. In particular, the compartmentalization of Na⁺ can help to absorb and reserve in the ions into the vacuoles，which is necessary to improve their osmotic adjustment and eventually enhance the salt tolerance of the plants. Potatoes are widely cultivated as a dual-purpose crop for food and vegetable consumption in the world. They are also one of the most important economic crops in arid and semi-arid areas in China. However, they are salt sensitive, and difficult to be selected and developed for a new variety with a stronger salt tolerance from limited genetic resources using traditional methodology. In this study, we constructed a pBI12135-GZ+AtNHX1 expression plasmid carrying a constitutive promoter (CaMV 35S), npt II gene (the resistance gene to Kanamycin) and AtNHX1 gene (the tonoplast Na⁺/H⁺ antiporter gene), and then attempted to introduce this constructed expression plasmid into the slices of microtubers of “Gannongsu 2” and the stems of “Kexin 2” potato cultivars mediated by Agrobacterium tumefaciens. After screening the transformed slices and stems on a medium containing 50 mg L^-1 Kanamycin and 300 mg L^-1 Cefotaxime, we obtained 30 transgenic plants from the slices at a regeneration rate of 37%, but none from stems. We further used specific primers to amplify the full-length of the AtNHX1 gene from total genomic DNA of the transgenic plants, of which 27 plants had a positive amplification, indicating 90% of successful transformation. Southern blot showed that two copies of the AtNHX1 gene were inserted into the genome of the transgenic plants and Northern blot hybridization detected a normal expression of the AtNHX1 gene at different levels among the transgenic plants. These results pave the way for the generation of a new potato variety with a stronger salt tolerance.

Transformation of Cotton (Gossypium hirsutum L.) with AhCMO Gene and the Expression of Salinity Tolerance

ZHANG Hui-Jun;DONG He-Zhong;SHI Yao-Jin;CHEN Shou-Yi;ZHU Yong-Hong

Acta Agron Sin. 2007, 33(07):  1073-1078. 

Abstract ( 2081 )   PDF (12630KB) ( 1801 )   Save

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Soil salinity is becoming a serious threat to global agriculture including cotton. Although cotton has been classified as a salt-tolerant crop, it is also seriously attacked by salinity especially during emergence and seedling growth. Levels of glycine betaine, an osmoprotectant accumulated in plants during abotic stresses, vary among cotton genotypes, and positively correlated with the degree of salt tolerance. Therefore, enhancing glycine betaine synthesis is one of the most promising ways to improve salt tolerance in cotton. Choline monooxygenase (CMO) catalyzes the committed step in the synthesis of glycine betaine. AhCMO, a gene cloned from Atriplex hortensis, was introduced into the cotton (Gossypium hirsutium L.) hypocotyl explants of SM3 via Agrobacterium mediation, and the transformed plants were regenerated through somatic embryogenesis in tissue culture. After selection with 0.5% kanamycin, the kanamycin-resistant regenerated plants were confirmed to be electropositive by polymerase chain reaction (PCR). Southern and Northern blotting analyses further indicated the introduction and the expression of AhCMO gene in transgenic cotton plants, respectively. At the two true-leaf stage, transgenic cotton seedlings were treated with 0.5% NaCl for 15 days under greenhouse conditions, plant height, fresh weight per plant and net photosynthetic rate were determined. The results showed that NaCl stress decreased plant height, fresh weight per plant and net photosynthetic rate by 37.3%, 54.6%, and 47.9% for transgenic plants, and by 57.6%, 65.6%, and 69.9% for non-transgenic SM3, compared with their corresponding NaCl-free controls, respectively. The fact that less injury of NaCl to transgenic plants than to non-transgenic plants, suggested that induction and expression of AhCMO considerably enhanced salinity tolerance of transgenic cotton plants. Transgenic cotton with improved tolerance against salt stress is of great agronomic value. However, it should be noted that the improvement in salt tolerance of the transgenic lines is still limited. An integration of the transgenic technology and the traditional breeding technique may further improve both salt-tolerance and other agronomic properties of cotton.

Comparisons of Plant Type, Grain Yield, and Quality of Different Japonica Rice Cultivars in Huanghe-Huaihe River Area

DU Yong;WANG Yan;WANG Xue-Hong;SUN Lai-Li;YANG Jian-Chang

Acta Agron Sin. 2007, 33(07):  1079-1085. 

Abstract ( 2151 )   PDF (757KB) ( 1195 )   Save

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Huanghe-Huai River area is an important rice-growing area in China and most rice cultivars used there are mid-season japonica ones. Today, little is known what traits should be for a cultivar with super-high-yielding and good quality in this district. The purpose of this study was to elucidate the characteristics of plant type, grain yield and quality of rice cultivars grown in Huanghe-Huaihe River area. One hundred and twenty-nine mid-season japonica rice cultivars and lines, used in the production, were field-grown and their morphological traits, grain yield and quality were investigated. The results showed that, by cluster analysis based on grain yield, 129 tested cultivars could be classified into five groups: super-high-yielding (13.57 t ha^-1), high-yielding (11.52 t ha^-1), mid-yielding (10.26 t ha^-1), mid-low-yielding (9.04 t ha^-1)，and low-yielding (7.57 t ha^-1). In the total tested cultivars, super-high-yielding cultivars were 3.1%, low-yielding cultivars were 14.7%, and other cultivars were 82.2%. Most of high- and super-high-yielding cultivars had half-erect and large panicles and erect leaves, produced more biomass, and had greater seed-setting rate, grain weight and harvest index. The cultivars with good grain quality were mainly in the high-yielding and mid-high-yielding groups, and very few in the super-high-yielding and low-yielding groups. The higher percentage of chalky grains was a major problem for the super-high-yielding cultivars. The traits or indexes for a super-high-yielding mid-season japonica rice cultivars were suggested, i.e., plant height 100–108 cm, whole growth period 150–155 d, half-erect panicles, panicle length 0.17–0.18 m, panicles 320–340 m^-2, primary branches 12–15, secondary branches 30–38, spikelets per panicle 160–180, seed-setting rate>85%, 1 000-grain weight 26–27 g, the length of the flag leaf, and the 2nd and 3rd leaves from the top were 0.26–0.28, 0.35–0.40, and 0.32–0.38 m, respectively, the angle of the flag leaf<20º, and harvest index>0.5.

Effects of Salt Stress and La³⁺ on Antioxidative Enzymes and Plasma Membrane H⁺-ATPase in Roots of Two Rice Cultivars with Different Salt Tolerance

CHEN Hai-Yan;CUI Xiang-Ju;CHEN Xi;LI Jian-You;ZHANG Wei

Acta Agron Sin. 2007, 33(07):  1086-1093. 

Abstract ( 2013 )   PDF (789KB) ( 1004 )   Save

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Plant tolerance to salinity is genetically and physiologically complex. Many mechanisms, such as ion compartmentalization, osmotic regulation and scavenging of reactive oxygen species, have been demonstrated. Among them, anti-oxidative enzymes play an important role in salt tolerant characteristic in plants. In addition, the plasma membrane P-type H⁺-ATPase (EC 3.6.1.3) also involved in the plant response to salinity by regulating the ion homeostasis and so on. Although the relationship between salt stress and anti-oxidative enzymes or PM H⁺-ATPase has been studied widely, the results varied with the different experimental materials. An interesting shortcut is to comparatively study plants naturally adapted to salt versus their more salt-sensitive relatives. In this report, changes in the activities of antioxidative enzymes and plasma membrane H⁺-ATPase from root tips are compared between salt-sensitive and salt-tolerant rice cultivars under NaCl stress, in the presence or absence of La³⁺. The results indicated that CAT and POD activities, but not SOD and APX activities, were higher in salt-tolerant cultivar than in salt-sensitive one. Under NaCl stress, especially in the range of 200–300 mmol L^-1 NaCl, external La³⁺ increased the activities of CAT, SOD, APX, and POD in salt-tolerant rice, but not in salt-sensitive cultivar, which suggests that external La³⁺ can lighten the oxidative damage of rice seedling roots, mainly at high salt concentration range. Plasma membrane H⁺-ATPase activities were suppressed by 30% under NaCl stress in salt-sensitive cultivar, and La³⁺ effectively alleviated such suppression. On the contrary, in salt tolerant cultivar, H⁺-ATPase activity increased by 32% under NaCl treatment, and La³⁺ had little effect on the activities. Semi-quantitative RT-PCR analysis demonstrated that the changes in PM H⁺-ATPase activities and La³⁺ effect under salt stress might occur at transcriptional level. Taken together, the data suggested that in salt-sensitive rice Wuyunjing 8, the root cytosolic Na⁺ concentration seems to be more dependent on the Na⁺ intracellular compartmentation capacity, while in salt-tolerant rice Jiucaiqing, NaCl induces plasma membrane H⁺-ATPase gene expression, indicating that the roots require increased H⁺-electrochemical potential gradient for the maintenance of ion homeostasis for osmotic regulation. In addition, the different effects of La³⁺ on the activities of anti-oxidative enzymes and plasma membrane H⁺-ATPase indicate that there might be completely different salt stress responding mechanisms between salt-sensitive and salt-tolerant rice cultivars.

Effects of Eco-Physiological Factors on Vitamin E Content in Soybean Seed

LI Wei-Dong;LU Wei-Guo;LIANG Hui-Zhen;WANG Shu-Feng;YUAN Bao-Jun;GENG Zhen;WANG Su-Ge;FAN Yan-Ying;LIU Ya-Fei;WANG Ling-Tao

Acta Agron Sin. 2007, 33(07):  1094-1099. 

Abstract ( 2072 )   PDF (1103KB) ( 996 )   Save

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Vitamin E (VE) is an important nutrient factor for human beings, and soybean seed is one of major available VE recourses. To reveal the correlation between VE content in soybean seed and ecological factors, the present experiment was carried out using soybean cultivar Yudou 25 sown at 5 locations of Henan province on 13 different dates in 2001 and 2002. The data of VE contents for the 109 samples of soybean seed and 33 eco-physiological factors including meteorological factors, soil nutrition and altitudes were obtained and used for statistical analyses. Step-wise regression was used to screen the correlated factors, which showed significant effect on VE content. Results indicated that the VE contents was substantially affected by the environmental conditions and ranged from 500.99 μg g^-1 to 2353.68 μg g^-1 among all samples. Nine eco-physiological factors were highly correlated with VE content, including 6 meteorological factors, 2 soil nutrition factors and altitude. VE content was negatively correlated with rainfall at seedling (P<0.01), rainfall at branching (P<0.001), rainfall at blooming and podding (P<0.001), diurnal temperature range at blooming and podding (P<0.05), hours of sunlight at seed-filling and maturity (P<0.001), and hydrolysable N (P<0.001), but positively correlated with total P content in soil (P<0.001) and altitude (P<0.001). While the VE content was positively correlated with hours of sunlight at blooming and podding (P<0.001), and negatively correlated with the square of the factor (P<0.01). The result of this experiment is meaningful for the development of soybean cultivars with higher VE and for the production of soybeans with more VE.

Genetic Diversity of Three Wild Rice Species in Hainan Province

SUN Xi-Ping;YANG Qing-Wen;LI Run-Zhi;WANG Xiao-Ning

Acta Agron Sin. 2007, 33(07):  1100-1107. 

Abstract ( 1984 )   PDF (676KB) ( 1188 )   Save

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The genetic diversity of three wild rice species in Hainan, China, was comparatively analyzed with 39 selected SSR markers which evenly distributed throughout rice genome and normally amplified bands in all three wild rice species. The results indicated that total 210 alleles were detected with 39 SSR primers. Polymorphic loci were 97.44% in Oryza rufipogon and 23.08% and 15.38% in meyeriana and O. officinalis respectively. Based on the related parameters, Oryza rufipogon showed the highest genetic diversity and O. officinalis maintained the lowest one. For instance, the percentage of polymorphic loci (P) and the mean number of alleles (A) per locus in O. officinalis were only 1/7 and 37% of those in O. rufipogon while those in O. meyerian were 2/7 and 39% of those in Oryza rufipogon respectively. Similarly, the average observed heterozygosity of O. rufipogon was the highest, which was 4.6 and 6.6 times of that of O. meyeriana and O. officinalis respectively. Wright’s F-statistics showed that the genetic variations within and among O. rufipogon populations were rather high, but those of both O. officinalis and O. meyeriana were very low, meaning that both individuals and populations of O. rufipogon have much different genetic backgrounds and those of the other two species have similar genetic backgrounds. The UPGMA clusters also showed that the three populations of O. rufipogon clustered into different groups at the point of I = 0.53, while the populations from the other two species grouped only after I = 0.9 or more. Similarly, the individuals within each population of O. rufipogon showed different genetic backgrounds with a few exceptions, but a lot of individuals in each population of both O. officinalis and O. meyeriana had the same genetic background. Considering above results, all tested populations of O. rufipogon and those with the highest genetic diversity of the other two species should be conserved with an in situ approach. O. meyeriana and O. officinalis should be conserved with only several individuals sampled in each population.

A Simulation Model on Leaf Color Dynamic Changes in Rice

CHANG Li-Ying;ZHANG Wen-Yu;ZHANG Yu-Pin;GU Dong-Xiang;YAO Xin-Feng;ZHU Yan;CAO Wei-Xing

Acta Agron Sin. 2007, 33(07):  1108-1115. 

Abstract ( 2040 )   PDF (754KB) ( 1201 )   Save

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With the development of digital agriculture, the visualization expression of plant growth process is very important. Quantifying the dynamic process of leaf color is the basic part of plant growth visualization. At present, the study on plant leaf color visualization at home and abroad is emphasized on reversing and rebuilding crop virtual growth with the figure identifying technique in computer, however, simulation model and visualization technique based on leaf color dynamic process have not been established successfully.
Modeling leaf color dynamics in rice is an important task for realizing virtual and digital plant growth. Based on time-course observations on leaf color changes at different leaf positions of stem and tillers under different nitrogen rates and water conditions with four rice cultivars, we developed a simulation model on leaf color dynamic changes in rice in relation to GDD. Leaf color changes in the model were described with SPAD in three phases. The first phase during leaf growth period was based on the exponential relationship of leaf color to cumulative GDD; the second phase during leaf function period was represented with a relative stable SPAD; the third phase during leaf senescence period was described in a quadratic equation between SPAD and GDD. In addition, the effects of nitrogen and water conditions on leaf color were quantified through the effectiveness values of leaf nitrogen concentration and water content in relation to SPAD. Then, the RGB values were further predicted from the changing SPAD. The model was validated with the independent field experiment data involving different rice cultivars and nitrogen rates. The average RMSEs between the simulated and observed SPAD dynamics at different leaf positions were 2.58, 3.69, and 3.82, respectively, for three leaf color phases on main stem, 4.65, 4.39, 3.51, and 4.25, respectively, for four individual tillers in rice, and 2.98, 3.25, respectively, for SPAD and R, G values.
The results indicate that the present model has a good performance in predicting leaf color changes at different leaf positions in rice under different growth conditions, and thus lays a foundation for further constructing digital and visual rice growth system.

Effects of Sulfur on Key Enzyme Activities Involved in Nitrogen and Sulphur Assimilation in Flag Leaves and Grain Yield under Different Nitrogen Levels in Winter Wheat (Triticum aestivum L.)

ZHU Yun-Ji;Li Guo-Qiang;GUO Tian-Cai;Wang Chen-Yang;DAI Ting-BO;CAO Wei-Xing

Acta Agron Sin. 2007, 33(07):  1116-1121. 

Abstract ( 1918 )   PDF (607KB) ( 1241 )   Save

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Sulphur (S) deficiency has become a marked problem in agricultural system in many regions in the last two decades, and sulphur application in S-deficiency soils may increase crop yield and improve the grain quality. In plants, there is a close relationship between sulphur and nitrogen. Crop response to S fertilizer often depends on the amount of N supply. Deficiency of S may be induced by a high nitrogen amount, and responses to S application are usually greater when abundant nitrogen fertilizer applied. Although wheat has a relatively low requirement for S, deficiency of S in wheat growth has been observed in many regions in China. Previous studies have focused on effects of single S fertilizer on growth and yield of wheat. We took a strong-gluten wheat (Triticum aestivum L.) cultivar Yumai 34 as experimental material to explore the activities of key enzymes for nitrogen and sulphur assimilation and the response of grain yield to different fertilizer applications of sulphur and nitrogen. The experiment was conducted in the soil with available sulphur content of 22.78 mg kg^-1 in 2003/2004 and 2004/2005 growing seasons by split plot design. The main plot was two nitrogen levels with 330 (N330) and 240 (N240) kg ha^-1, respectively, and the subplot was three sulphur levels with 0 (S0), 60 (S60), and 100 (S100) kg ha^-1, respectivly. The results indicated that sulphur fertilizer could improve the activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamic-pyruvic transaminase (GPT), which are the key enzymes of nitrogen assimilation, and may be speculated to improve the nitrogen assimilation ability. But, under different nitrogen application levels, the amount of sulphur needed was different. In N330 treatment, sulphur application could reduce NR activity and improve GS and GPT activities. In N240 treatment, 0 sulphur application could improve NR and GS activities. The activity of o-acetylserine thiollyase (OASS), a key enzyme of sulphur assimilation, reduced with inreasing of sulphur application rate. Furthermore, OASS activity enhanced under high N-supply and S-deficiency conditions. The effects of N and its interaction with S on grain yield were significant (P<5%) , and those of S were highly significant (P<1%). Under the both nitrogen levels of N330 and N240, dry matter accumulation of S application treatments increased significantly as compared with that of control (S0), and the grain yield of N330S100, N330S60, N240S100, and N240S60 treatments rose by 28.6% (P＜0.01), 12.6% (P＜0.05), 25.7% (P＜0.01), and 25.3% (P＜0.01) respectively. The 1000-grain weight of sulphur treatments significantly increased at both nitrogen levels, but the spike number and grains per spike had no significant difference among the treatments.

Dynamic Changes of Activities of Key Enzymes Involved in Sucrose Metabolism during Grain Filling in Wheat and the Relationship with Starch Accumulation in Grain

WANG Wen-Jing;WANG Guo-Jie;WANG Yong-Hua

Acta Agron Sin. 2007, 33(07):  1122-1128. 

Abstract ( 1991 )   PDF (667KB) ( 1326 )   Save

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Sucrose and starch are the main product of wheat photosynthesis. During sucrose metabolism, Sucrose phosphate synthase (SPS) is the key enzyme controlling sucrose synthesis, but sucrose synthase (SS) is the key enzyme controlling sucrose degradation. In the present experiment conducted in cement cultural pool, three winter wheat (Triticum aestivum L.) cultivars GC8901 (strong gluten), YM49 (medium gluten) and LM1 (weak gluten) were used to investigate the activities of the key enzymes involved in sucrose metabolism in leaf, sheath, ear stem and grain during grain filling and the relationship with starch accumulation in grain. Ten main tillers of each plot were sampled at 6, 12, 18, 24, 30, and 36 days after anthesis, and partitioned into flag leaf, sheath of flag leaf, and ear stem.One hundred grains of each plot were sampled from the spikes from which only two basal grains of the 4th to 12th spikelets were collected. Half of the plant samples were used to determinate the enzyme activities, and the other half for starch content measurement.In the three cultivars, the dynamic changes of activities of sucrose phosphate synthase(SPS) and sucrose synthase(SS) in leaf, sheath, ear stem and grain during grain filling period all fit the single-peak curve. The SPS activity in flag leaf, flag leaf sheath and grain of YM49 was higher than that of other two cultivars, but the SPS activity in ear stem of LM1 was higher than that of other two cultivars. The SS activity in flag leaf, flag leaf sheath, ear stem and grain of YM49 was higher than that of other two cultivars,indicating the sucrose synthesis and degradation in the vegetative organs and grain of YM49 and LM1 were active. Correlation analysis showed that the starch and amylopectin accumulation in the grain of YM49 and LM 1 had strong feedback regulation to sucrose synthesis catalyzed by SPS. The SS activities in the grain of YM49 and LM1 were significantly(P＜0.01) correlated with the starch and amylopectin accumulating rate, but that of GC8901 was not. The results suggested that the SPS and SS activities in the vegetative organs and grain in three different wheat cultivars were closely related to starch accumulation.

Differences and Correlations of Starch Physicochemical Properties among Different Wheat Cultivars

LI Chun-Yan;FENG Chao-Nian;WANG Ya-Lei;ZHANG Rong;GUO Wen-Shan;ZHU Xin-Kai;PENG Yong-Xin

Acta Agron Sin. 2007, 33(07):  1129-1134. 

Abstract ( 1907 )   PDF (590KB) ( 969 )   Save

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Starch physicochemical properties include viscosity, crystallinity, gelatinization and thermal properties, which can directly or indirectly affect dough and final products qualities. Many researches showed that the correlation of starch granule size, amylose content and ratio of amylose content to amylopectin content with viscosity properties was significant. We studied starch viscosity property, damaged starch content and crystal property in different types (waxy or non-waxy) of wheat or wheat cultivars and their reciprocal relationship in Yangzhou University. Pasting properties of starch were measured by the Rapid Viscosity Analyser Super3 (Newport Co., Australia). Four different types of viscosity profiles were got. For strong-gluten wheat, final viscosity value was higher than peak viscosity value. For medium-gluten wheat, final viscosity value was slightly higher than peak value or almost the same. For weak-gluten wheat, final viscosity value was a little lower than peak value or almost the same. The pasting parameters of waxy wheat were lower than those of the others (non-waxy). There was significant difference in RVA profile among different cultivars with the same type (strong-gluten, mediate-gluten, weak gluten or waxy wheat), which induced the changes of pasting parameters after their reaching peak viscosity. During milling, some starch granules can be mechanically damaged. Different cultivars flour milled by Branbender mill had different damaged starch content, which were tested by SDmatic (Sweden). The order of damaged starch content of wheat flour was strong-gluten wheat>medium-gluten wheat>weak-gluten wheat>waxy wheat. X-ray diffraction of flour investigated with Diffractomes Bruker Axs D8 Advance (Germany) in different wheat cultivars showed their peaks at angle 15º, 20º, 23º, 17º, and 18º, which retained the typical A-type pattern. The order of intensities of X-ray diffraction peaks was 18º>17º>23º>15º>20º, which was the main difference among them. Degree of crystallinity ranged from 28.97%–36.97%. It might be concluded that amylose content, the ratio of amylose content to amylopectin content and damaged starch content have significant effects, while crystallinity has no significant effect on starch pasting properties.

Optimization of the Agrobacterium-Mediated Transformation System on Upland Rice

SHI Yun-Lu;DING Zai-Song;ZHANG Bin;ZHANG Gui-Fang;ZHAO Ming

Acta Agron Sin. 2007, 33(07):  1135-1140. 

Abstract ( 1953 )   PDF (4267KB) ( 1453 )   Save

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Agrobacterium mediated transformation has been used very successfully in some monocot plant such as rice (Oryza sativa L.) and maize (Zea mays L.); by which the transgenic plants obtain stronger resistance or better characters. But the efficiency of Agrobacterium mediated transformation system is still not so high as our expectation. Upland rice is a variety of rice (Oryza sativa L.), which has many good characters, such as drought resistance, and tolerance to sterile soil. Upland rice has been praised as one of the new source of food supplies in the 21st century in China. However, studies on the Agrobacterium mediated transformation system of upland rice are less compared with these of rice, and a lot of problems that affected the transformation efficiency should be solved. So setting up an effective transformation system of upland rice is still a challenge to investigators. Several important factors affecting upland rice transformation mediated by Agrobacterium were investigated with 4 upland rice cultivars.
In this paper callus induced from mature embryos of upland rice seeds were used mediated as explants to study the factors affecting the transformation rate. Callus were collected in a sterile trigonal bottle, Agrobacterium suspension was then added to the bottle, and vortexed for 30 s, followed by a 20 min of soaking in the bacteria solution. The callus were then transfered on co-cultivation medium(C-C1 or C-C2) in Petri plates and cultured in the dark for 3 days. After washed with sterile water, the explants were then put onto SX medium containing hygromycin for selection. After 6–8 weeks, surviving callus were transferred to differentiation medium. Then, the induced seedlings in 4–5 centimeters long were transferred onto root-inducing medium Finally, they were transplanted into soil when the roots had formed, and identified by PCR and Southern blot.
The transformation rate was affected by five factors in this process. NB medium was suitable for callus induction and subculture. Re-suspending the strain by AAM-AS medium before transformation could improve the resistant callus rate significantly. After infected by the strain, the callus were put on the 2 layers of sterile filter papers (d=12 cm) absorbed 4 mL C-C2 medium for co-cultivation, instead of being on agar medium, which could improve the resistant callus rate of NPT from 2% to 31.7%. Before selection and regeneration, desiccation for 2 days on sterilized filter papers could increase the resistant callus rate. Adding 10 mg L^-1AgNO₃ or 8 mg L^-1CuSO₄ into the differentiation medium could improve the regeneration rate, especially for the callus subculturd for 2 months or longer. many putative transgenic plants identified by PCR were acquired by using this transformation procedure, and southern blot analysis showed the target gene integrated in most transgenic plants just by single copy.


Prediction Canopy Leaf Nitrogen Content of Winter Wheat Based on Reflectance Spectra in Different Directions

XIAO Chun-Hua;LI Shao-Kun;WANG Ke-Ru;LU Yan-Li;XIE Rui-Zhi;GAO Shi-Ju

Acta Agron Sin. 2007, 33(07):  1141-1145. 

Abstract ( 1961 )   PDF (4018KB) ( 1073 )   Save

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In order to improve the method of nitrogen spectral diagnosis, we conducted a experiment with two winter wheat (Triticum aestivum L.) cultivars Jing 411(low protein content) and Zhongyou 9507(high protein content) under nitrogen application levels of 0, 100, 200, and 400 kg N ha^-1. The wheat canopy spectral reflectance over 350–2 500 nm and canopy leaf nitrogen contents (CLNC) were measured at tillering, jointing, heading, milking, and mature stages. Seven vegetation indices (VIs) with view angles of 0°, 30°, 60°, 90°, 120°, 150°, and 180° to the vertical line to wheat row were compared with corresponding CLNC. The results indicated that CLNC had most significant correlations with RVI[670,890] among seven spectrum vegetation indices, especially in the view angles of 0°, 30°, and 90°, and the predicting models for CLNC were further established on the basis of the correlations. The coefficient of determination (R²) of three models were sequenced as: 0°＞30°＞90°. Root mean square error (RMSE) and R2 between measured and estimated CLNC were employed to test the model reliability and predicting accuracy. RMSE and R² were different in different view angles and cultivars, the model based on the view angle of 0°had RSME of 0.2915 and R² of 0.902 for Jing 411, and RSME of 0.3824 and R² of 0.872 for Zhongyou 9507. There were lower RMSE and higher R² in the model established based on the view angle of 0°than in that of other angles. The correlation was different between canopy spectral reflectance and CLNC in different cultivars, indicating that different predicting models should be selected based on different cultivars.

Molecular Characterization and Expression Analysis of Two Genes Encoding Hybrid Proline-Rich Proteins in Cotton

XU Wen-Liang;HUANG Geng-Qing;WANG Xiu-Lan;TAI Fu-Ju;WANG Hong;LI Xue-Bao

Acta Agron Sin. 2007, 33(07):  1146-1153. 

Abstract ( 1845 )   PDF (600KB) ( 1076 )   Save

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We identified two cDNAs (designated as GhHyPRP1 and GhHyPRP2) encoding putative cell wall hybrid proline-rich proteins (HyPRPs) from cotton (Gossypium hirsutum) ovule and fiber cDNA libraries. GhHyPRP1 and GhHyPRP2 encode 327 and 137 amino acids, respectively. Both GhHyPRP1 and GhHyPRP2 proteins have the same overall primary structure: an amino-terminal signal peptide; a central proline-rich domain that contains nine copies of 13 peptide repeat for GhHyPRP1 (similar to PPTYAPPPKSPSK), and 10 copies of double peptide repeat for GhHyPRP2 (similar to CP); and a carboxy-terminal nonrepetitive domain with a certain number and specific distribution of cysteines which is in GhHyPRP1 six cysteines and a typical eight-cysteine motif (8 CM) in GhHyPRP2. Based on the protein domain organization and protein similarity, GhHyPRP1 was grouped into the HyPRP class A proteins, while GhHyPRP2 into the HyPRP class B proteins of higher plants. Phylogenetic relationship alalysis clearly showed that GhHyPRP1 and GhHyPRP2 were separated into two subgroups, in the top of different clade respectively, demonstrating that they were evolutionally far related which are consistent with the results based on protein domain organization and protein similarity analysis. Expression analysis of the two GhHyPRPs was carried out by quantitative realtime RT-PCR. The results showed that GhHyPRP1 was highly expressed in hypocotyls, while GhHyPRP2 expressed preferentially in 10 dpa ovule. The results suggest that GhHyPRP1 and GhHyPRP2 may play a role in the development of different cotton tissues.

Photosynthetic Performance in the Leaves of Different Mung Bean Genotypes

GAO Xiao-Li;SUN Jian-Min;GAO Jin-Feng;FENG Bai-Li;CHAI Yan;JIA Zhi-Kuan

Acta Agron Sin. 2007, 33(07):  1154-1161. 

Abstract ( 1773 )   PDF (667KB) ( 1101 )   Save

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Photosynthesis is closely related to crop growth and yield, and higher photosynthetic rate of leaves is one of the important factors for high crop yield. The study explored the changes of photosynthetic indexes of the leaves at different flowering nodes in high-yield mung bean varieties Jilü 2 and An 9910, and low-yield varieties Chifeng and Tailai adopted in the summer planting region，thus to clarify the physiological characteristics affecting seeds yield and photosynthetic performance of the leaf in mung bean at the late growth stage. The results showed that after flowering, the leaves gradually aged, the net photosynthetic rate (Pn), transpiration rate (T_r), stomata conductance (G_s), chlorophyll and soluable protein contents of its functional leaves gradually declined, but the intercellular carbon dioxide concentration (C_i) of the leaves tended to rise, specific leaf weight tended to decline-rise-decline. The photosynthetic capacities of the leaves appeared to decline from the upper nodes to the lower nodes. Compared with low-yield varieties, the leaves of Jilü 2 and An 9910 had a longer functional period, declining slowly in chlorophyll and soluable protein contents and maintaining higher photosynthetic capacity at the late growth stage, which provided a good physiological foundation for higher amount of accumulated photosynthates . Further analysis indicated, there were significant positive correlations between seed yield and average net photosynthetic rates of leaves at flowering nodes(r = 0.999), and between net photosynthetic rate and the contents of chlorophyll and soluble protein at the late growth stage. In summary, at the crucial stage of yield formation, maintaining higher chlorophyll content and photosynthetic capacity of functional leaves, and delaying leaf aging have important action for increasing crop yield.

Clustering Fusion for Preharvest Cotton Grades Based on Image Features

WANG Ling;JI Chang-Ying;CHEN Bing-Lin;LIU Shan-Jun

Acta Agron Sin. 2007, 33(07):  1162-1167. 

Abstract ( 1580 )   PDF (553KB) ( 1075 )   Save

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In order to assess preharvest cotton grades, according to Chinese government grading standard, clustering fusion was performed based on machine vision technologies by using K-means and competitive learning network to grade cotton quality with 7 categories renewedly based on their size, white, impurity and yellow in Ohta, HIS, and Hunter Color Spaces. Correlation analysis showed that the Peason’s correlations among image features were significant at the 0.01 probability level by adjusting image intensity and Hunter Color Space to an approximate optimum; clustering by human eyes did not consider all image features uniformly with fitting coefficients of quadratic polynomial of 0.55–0.98 (0.88, 0.94, 0.98, 0.55) between cluster center of image features and grade value of cotton quality; individual clustering by K-means and competitive learning network also did not consider all image features uniformly with fitting coefficients of 0.32–0.74 (0.74, 0.63, 0.70, 0.32) and 0.39–0.94 (0.85, 0.39, 0.94, 0.84), respectively; and their clustering fusion considered all image features uniformly with fitting coefficients of 0.71–0.99(0.89, 0.71, 0.99, 0.83). Bayes quadratic discriminants analysis for cotton graded showed that clustering by human eyes recognized the 1st, 2nd, 7th grades with accuracies of 73%–100%, the grades 3–6 with accuracies of 26%–46%, and total accuracy of 47.7%; accordingly, clustering by K-means recognized each grade with accuracies of 93%–100%, and total accuracy of 96%; clustering by competitive learning network recognized each grade with accuracies of 79%–95%, and total accuracy of 86%; clustering fusion recognized each grade with accuracies of 65%–100%, and total accuracy of 78.6%. On the whole, the average quality grade of clusering fusion was 4.33 while that of clustering by human eyes was 4.57, and the specimens with large recognization difference between the two methods were less than 1/3 of the total. Compared with by human eyes, clustering fusion can use each image feature more adequately and uniformly with the wider range of vision based on human’s previous knowledge, and overcome the over-training of individual clustering, further, grade preharvest cottons objectively to improve high-quality cottons to be purchased, and this method can be generalized effectively to meet different environments.

Responses of Physio-Biochemical Properties to N-Fertilizer Application and Its Relationship with Nitrogen Use Efficiency in Rice (Oryza sativa L.)

ZENG Jian-Min;CUI Ke-Hui;HUANG Jian-Liang;HE Fan;PENG Shao-Bing

Acta Agron Sin. 2007, 33(07):  1168-1176. 

Abstract ( 2175 )   PDF (848KB) ( 1284 )   Save

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Improvement in nitrogen use efficiency (NUE) in crop plants is significant in the view of economic efficiency and environment friendly. A better understanding of the physiological mechanism underlying nitrogen use efficiency is necessary for genotype screening and breeding rice cultivar with high NUE. In present study, four rice genotypes identified as high and low nitrogen use efficiency (NUE) were used to investigate their responses of physio-biochemical properties to N-fertilizer and its relationship with NUE at the rate of 0, 0.51, 1.02, 1.53, and 2.04 g N pot^-1 (equivalent to 0, 75, 150, 225, 300 kg N ha^-1, respectively) under pot-grown conditions. The results showed that the soluble protein content in leaves was relatively lower in high-NUE genotypes than that in low-NUE genotypes at panicle initiation stage, while the glutamine synthetase (GS) activity was higher significantly. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) content in leaves appeared to be no significant difference between two NUE types of rice. The net photosynthetic rate (P_n) in the low-NUE genotypes was significantly lower by 28.66% in comparison with that in high-NUE genotypes at full heading stage, regardless of no significant difference at panicle initiation stage. Interestingly, P_n per chlorophyll unit (P_n/Chl) was lower in low-NUE genotypes than in high-NUE genotypes at both two stages by about 18.51% and 29.67%, respectively. Total aboveground biomass and grain yield at five nitrogen levels were significantly higher in high-NUE genotypes than those in low-NUE genotypes. It was observed GS activity was significantly correlated with biomass at harvest stage at the rate of 0, 0.5, 1.0, and 1.5 g N pot^-1. P_n at full heading stage, GS activity, and P_n/Chl were all significantly and positively correlated with agronomy efficiency (AE), partial factor production of applied N (PFP), and nitrogen physiology efficiency (NUEb), respectively. However, PFP, AE, and NUEb were negatively correlated with soluble protein content in leaves, respectively. Additionally, no significant correlation was observed between nitrogen recovery efficiency (RE) and the physiological parameters mentioned above. The results presented in the paper suggest the important contributions of Pn and GS to NUE. According to the relationships among NUE, GS and soluble protein content, GS activity and soluble protein content in leaves might be candidate indicators for NUE evaluation in rice.

Responses of Pollen Activity and Seed Setting of Rice to High Temperature of Heading Period

ZHANG Bin;RUI Wen-Yi;ZHENG Jian-chu;ZHOU Bo;YANG Fei;ZHANG Wei-Jian

Acta Agron Sin. 2007, 33(07):  1177-1181. 

Abstract ( 2130 )   PDF (484KB) ( 1242 )   Save

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The field experiment was conducted using four rice cultivars (Nanjing 41, Wuxiangjing 14, Yangdao 6, and Shanyou 559) with the treatment of the temperature (40±0.2)℃ for five hours (10:00–15:00) at the 1st day of rice heading. The results showed that rice pollen activity decreased with the delaying flowering time under normal temperature, and significantly reduced by high temperature (P<0.05). The difference of pollen activity between under high and under normal temperatures decreased with the delaying of flowering time, with in the highest decrement in the day of treatment or the first day after treatment. Pollen germination rate on stigmas, pollen germination rate on culture medium and stainable pollen grain rate by I-KI of the four cultivars on average under high temperature were 16.00, 25.85, and 11.74 percentage points lower than those under normal temperature at that time, and 8.49, 6.63 and 6.02 percentage points lower than those under normal temperature at 4 days after treatment. The seed setting rate of four cultivars on average under high temperature were 14.04 percentage points lower than that under normal temperature at the day of treatment, and 5.95 percentage points lower than that under normal temperature at 4 days after treatment, but empty grain and unfilled grain rates of four cultivars on average under high temperature were 10.06 and 3.98 percentage points higher than those under normal temperature at the day of treatment, and 3.98 and 1.97 percentage points higher than those under normal temperature at four days after treatment, respectively. In addition, significant difference of temperature effects on pollen activity and seed setting existed among the four cultivars with the least impact in Shanyou 559. According to the regression analysis, the rates of seed setting, empty grain and unfilled grain showed a significantly linear correlation with the rates of pollen germination on stigmas and on culture medium (P< 0.05), respectively. The above results suggest that the potential heat injury of short-term high temperature to rice pollen activity and seed setting is decreased with the delaying of flowering time and that the rates of pollen germination on stigmas and an culture medium may be the suitable indicators for selective breeding of heat resistance and the prediction of heat injury probability and degree.

Grain Yield and Protein Property of Chinese and CIMMYT Hard Spring Wheats in Four CIMMYT Management Environments

ZHANG Yong;HE Zhong-Hu;WU Zhen-Lu;ZHANG Ai-Min;van Ginkel Maarten

Acta Agron Sin. 2007, 33(07):  1182-1186. 

Abstract ( 1966 )   PDF (422KB) ( 1080 )   Save

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The effects of moisture stress, sowing date and planting method on grain yield and protein properties were evaluated using 21 hard spring wheat cultivars, which were grown in Obregon experiment station in CIMMYT across two seasons from 2000 to 2002 under four management environments. All traits investigated were significantly influenced by cultivar and management environment main effects, among which grain yield and SDS sedimentation value were also significantly influenced by cultivar and management interaction. Cultivar by management environment interactions should be accommodated in evaluation and selection of cultivars within the operation of breeding program for grain yield and quality improvement. It was helpful to elevate protein content and gluten strength when planted on bed, reduced irrigation and late sowing, while sown at normal time with full irrigation increased grain yield. Rayon F 89 performed high grain yield, protein content and SDS sedimentation value. Longmai 26 performed much higher grain yield, protein content and SDS sedimentation value than the other three photosensitive cultivars. Cultivars differed in response to irrigation, sowing date and planting method, which changed the rankings for grain yield and SDS sedimentation value. Full irrigation, sown on normal date, and planted on bed (FNB) treatment elevated grain yield for Rayon F 89, and SDS sedimentation value for Weaver. Full irrigation, sown on normal date, and planted on basin (FNF) treatment elevated grain yield for Seri M 82, and SDS sedimentation value for Attila. Full irrigation, sown one month later than normal date, and planted on bed (FLB) treatment increased grain yield for Longmai 26, and SDS sedimentation value for Super Seri#1, whereas reduced irrigation, sown on normal date, and planted on bed (RNB) treatment increased grain yield for Rayong F 89 and Xinchun 6, and SDS sedimentation value for Weaver. It is very important to take the effect of cultivar-by-environment interaction into consideration when improving wheat quality.

Comparison of Ear Vascular Bundles in Different Maize Cultivars

HE Qi-Ping;DONG Shu-Ting;GAO Rong-Qi

Acta Agron Sin. 2007, 33(07):  1187-1196. 

Abstract ( 1999 )   PDF (13504KB) ( 1198 )   Save

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In addition to sink and source, drain is also an important factor in crop yield forming. Being the organ of drain, vascular bundle (Vb) has been studied widely in recent years. In rice and wheat, researches showed that the number and area of Vb in culm (neck-panicle, branch) were positively correlated to panicle characters; cultivation factors, such as planting density, fertilizer and chemical regulator, affected the development of Vb; the Vb structure was mainly determined by cultivar type. In maize, the related studies, which started later than those in rice and wheat, have focused on the relations between Vb structure and sink capacity of ear and kernel. There are very few reports based on maize cultivar type or genotype. In maize production, vertical-type cultivars are commonly utilized. Researches showed that high yield of vertical-type cultivar is contributed by its sufficient source and large sink, however, the function of drain was seldom mentioned. The present experiments were designed to compare Vb structure and function of maize ear in cultivars with different plant types and ear types.
We choose three types of maize hybrids as tested materials, namely Yedan 4, Yedan 13, and Shendan 7, corresponding to vertical-small-ear type, vertical-large-ear type and horizontal-large-ear type, respectively. The number and area of Vb, phloem, xylem, the number and diameter of vessel were measured using bare-handed sections. The quantity of bleeding sap from ear-stalk and its sucrose content were determined. The effects of planting density and plant growth regulators on Vb structures and function and sink capacity were initially explored.
The number of big Vb and total Vb, the average area of single big Vb, total area of big Vbs, total area of all Vbs in ear-pedicel (ear-axis) of Yedan 13 and Shendan 7 (large-ear type) were significantly superior to those of Yedan 4 (small-ear type). The relative area and density of ear Vb of Yedan 4 and Yedan 13 (vertical type) were larger than those of Shendan 7 (horizontal type). The vertical -large-ear type Yedan 13 had certain superiority on the quantity and transportation rate of bleeding sap from ear-stalk. Planting density had a significant effect on the number and area of ear Vb and the response of cultivars to planting density was different. Dealing with plant growth regulators GA₃ and 6-BA could increase the number and area of big Vb in ear-pedicel. Volume of fresh grain, endosperm cells of single grain and 1000-kernel weight were also raised.

RESEARCH NOTES

Responses of Enzyme Activities in Carbon Metabolism to Chilling Stress in Rice with Different Chilling Tolerance

WANG Guo-Li;GUO Zhen-Fei

Acta Agron Sin. 2007, 33(07):  1197-1200. 

Abstract ( 1914 )   PDF (293KB) ( 1211 )   Save

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Two cultivars of rice (Oryza sativa L.), Xiangnuo 1 (chilling-tolerant) and IR50 (chilling-sensitive), were used to study the responses of enzyme activities of carbon assimilation and metabolism to chilling stress. Seedlings of rice were transferred into growth chambers for 5 days at 8℃ as chilling treatment, or at 28℃ as control. The results showed that the activities of RuBPCase, RuBPOase, and FBPase as well as carbonation/oxygenation ratio were less influenced in the chilling-tolerant cultivar, Xiangnuo 1, while those in the chilling-sensitive cultivar, IR50 were decreased under chilling stress. The activities of SPS and SS in both cultivars were increased under chilling stress. Higher levels of SPS and SS activity were maintained in the chilling-tolerant cultivar than in the chilling-sensitive cultivar. Moreover, the changed tendency in the levels of total soluble sugars, sucrose and fructose were similar to those of SS and SPS. The results indicated that the changes in enzyme activities of carbon assimilation and metabolism were in consistence with the differential tolerance to chilling in two cultivars.

Starch Structure and Paste Property of Rice with Different Amylose Content

ZHANG Yan-Xia;DING Yan-Feng;LI Gang-Hua;WANG Qiang-Sheng;HUANG Pi-Sheng;Wang Shao-Hua

Acta Agron Sin. 2007, 33(07):  1201-1205. 

Abstract ( 2300 )   PDF (4498KB) ( 1562 )   Save

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Four rice cultivars with different amylose content were used to investigate the starch structure and RVA pasting properties in this study. The results showed that differences existed between rice cultivars. Relative crystallinity decreased and setback viscosity increased with increasing amylase content, and there were significant negative and positive correlations between relative crystallinity and amylose content, amylase content and setback viscosity, respectively(r=－0.964*, r=0.997**). Correspondingly, the significant negative correlation of setback viscosity with relative crystallinity was discovered (r=－0.960*). The crystallinity patterns of in four rice starch cultivars showed as typical A type with amylose content ranged from 3.43%–21.65%. Endosperm structure was different between glutinous or low-amylose and non-glutinous or high-amylose rice, and the arrangement and shape were different between the dorsum and abdomen in amyloplast of rice endosperm. The results implied that the shapes and arrangements of starch granule in endosperm might influence the relative crystallinity of rice starch.

Genetic Diversity Analysis of Cowpea Germplasm Resources by SSR

XU Yan-Hong;GUAN Jian-Ping;ZONG Xu-Xiao

Acta Agron Sin. 2007, 33(07):  1206-1209. 

Abstract ( 1979 )   PDF (314KB) ( 1127 )   Save

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Thirteen reproducible and informative SSR primer pairs were selected from the 46 candidates. A representative set of 316 cowpea genetic resources from China, Africa and other countries of Asia, were analyzed by SSR methodology using these informative primer pairs. A total of 47 alleles were detected with an average of 3.692 alleles per SSR primer pair, and on an average 2.003 alleles from each SSR primer pair were effective. According to integrated evaluation, five SSR primer pairs, VM16, VM26, VM20, VM25, and VM23, were most effective for genetic diversity studies of cowpea. The dendrogram by UPGMA cluster analysis showed that 260 accessions of the 316 were distinct and revealed enough genetic diversity for identification and classification of accessions within Vigna unguiculata. There was a clear difference between foreign and Chinese genetic resources. Within Chinese accessions, 8 distinct groups including two northern groups, four southern groups and two complex groups, were detected, indicationg that the Chinese breeding lines have a narrow genetic background.

Molecular Identification and Electron Microscopy Detection for Pathogen of Sugarcane Yellow Leaf Syndrome

GAO San-Ji;GUO Jin-Long;CHEN Ru-Kai;HUANG Xiao-Di;XU Jing-Sheng;WANG Qin-Nan

Acta Agron Sin. 2007, 33(07):  1210-1213. 

Abstract ( 1998 )   PDF (18924KB) ( 1030 )   Save

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Causal organism of sugarcane yellow leaf syndrome (YLS) was identified by electron micrographs, RT-PCR and tissue blot immunoassay (TBIA) in Fuzhou, China. Virus particles like sugarcane yellow leaf virus (SCYLV) were found in phloem companion cells from plant with YLS symptoms by electron micrographs. A 556 bp fragment was amplified by RT-PCR. The sequences of cDNA and its amino acids suggested that the fragment was a part of gene of coat protein that shared above 95% homology with SCYLV isolates from other countries. Positive reaction appeared as dark purple spot at the location of the phloem cells by TBIA. The above results suggested that pathogen of sugarcane yellow leaf syndrome is SCYLV in Fuzhou.

Analysis of Relative Gene Expression Using Different Real-time Quantitative PCR

YU Shun-Wu;LIU Hong-Yan;LUO Li-Jun

Acta Agron Sin. 2007, 33(07):  1214-1218. 

Abstract ( 3890 )   PDF (443KB) ( 1220 )   Save

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Real-time quantitative PCR is often used to analyze the target gene expression variation. The most commonly used methods to analyze data from real-time quantitative PCR include two types: absolute quantification and relative quantification. To avoid the complex of absolute quantification and simplify the relative quantification, the methods of 2^-ΔΔCT, 2^-ΔCT and standard curve were used to analyze the OsRDB1 expression variation under different chemical and hormone treatments in this study. The ratio of gene expression variation was calculated with the slope of standard curve. The results revealed that the 2^-ΔΔCT method had to be introduced a housekeep gene as a control, with a complicated calculation and the relative ratio was deviated by PCR amplification efficiency. The 2^-ΔCT and standard curve methods were convenient and saved chemicals used in the quantitative PCR, but the results were liable to the effect of the veracity of the RNA concentration. The modified method of standard curve introduced the curve slope to eliminate the effect of amplification efficiency, and the result of standard curve method most closely revealed the diversity of original copy.