Table of Content

12 April 2008, Volume 34 Issue 04

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CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS

Mapping QTLs Associated with Resistance to Fusarium Head Blight Using an “Immortalized F₂” Population

TIAN Da-Gang;LIN Feng;ZHANG Cai-Qin;ZHANG Zheng-Zhi; XUE Shu-Lin;CAO Yong;LI Chun-Jun;MA Zheng-Qiang

Acta Agron Sin. 2008, 34(04):  539-544.  doi:10.3724/SP.J.1006.2008.00539

Abstract ( 1999 )   PDF (197KB) ( 1866 )   Save

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Fusarium head blight (FHB) or scab disease, caused by Gibberrella zeae (Schw.) Petch, is a serious disease in many wheat (Triticum aestivum L.) growing regions worldwide. To study the inheritance of scab resistance against fungal penetration (type I resistance), an 198 lines “immortalized F₂”population was constructed by crossing between recombinant inbred lines chosen by random permutation of 132 RILs from the RIL population derived from the cross between scab-susceptible cultivar Nanda 2419 and scab-resistant cultivar Wangshuibai. The population were then evaluated for percentage of infected spikes (PIS) across two years and six chromosome regions were detected for their association with type I resistance through interval mapping, among which Qfhi.nau-4B and Qfhi.nau-5A with the resistance alleles originated from Wangshuibai and Qfhi.nau-2B with the resistance allele from Nanda 2419 were consistently detected. Qfhi.nau-4B and Qfhi.nau-5A had the largest effects among the detected QTLs and both showed mainly the additive allelic effects, the former also had partial dominance. In addition, four pairs of significant interaction loci were identified. These results further demonstrate that wheat scab resistance are under complex genetic control and also imply that early generation selection for type I resistance in scab resistance breeding is feasible with Wangshuibai as the parent.

Identification and Molecular Mapping of the Powdery Mildew Resistance Gene in Wheat Cultivar Yumai 66

HU Tie-Zhu;LI Hong-Jie;LIU Zi-Ji;XIE Chao-Jie;ZHOU Yi-Lin;DUAN Xia-Yu;JIA Xu;YOU Ming-Shan;YANG Zuo-Min;SUN Qi-Xin;LIU Zhi-Yong

Acta Agron Sin. 2008, 34(04):  545-550.  doi:10.3724/SP.J.1006.2008.00545

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Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important diseases of wheat (Triticum aestivum L.) worldwide. Breeding for resistance is the most economical and effective method for controlling the disease. Yumai 66, a common wheat cultivar derived from a wheat-triticale cross, is resistant to a wide spectrum of wheat powdery mildew isolates from both China and Canada. In the present study, genetic analysis indicated that Yumai 66 carried a single dominant gene for resistance to powdery mildew, designated tentatively PmYm66. The segregating F₂ populations and their F₃ progenies of the crosses Yumai 66/Mingxian 169 and Yumai 66/ND3509 were used for bulked segregation analysis (BSA). Four molecular markers were associated with PmYm66 in an order of EST48–EST83 (EST84)–Xksum193–PmYm66. These SSR and EST markers were assigned to the distal bin of chromosome 2AL by means of Chinese Spring nullisomic-tetrasomic, ditelisomic, and deletion lines. The reaction types of Yumai 66 to 21 B. graminis f. sp. tritici isolates from China was different from that of Pm4a and Pm4b located on chromosome 2AL.

QTL and Epistasis for Low Temperature Germinability in Rice

JI Su-Lan;JIANG Ling;WANG Yi-Hua;LIU Shi-Jia;LIU Xi;ZHAI Hu-Qu;YOSHIMURA Atsushi;WAN Jian-Min

Acta Agron Sin. 2008, 34(04):  551-556.  doi:10.3724/SP.J.1006.2008.00551

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High germination ability at relatively low temperature is essential for direct-seeding rice varieties. A recombinant inbred line population (RILs), derived from a cross between varieties Kinmaze (japonica) and DV85 (indica) was used to detect QTL for low temperature germinability (LTG). The germination rate at 15℃ after 10 d germination culture in Nanjing, Jiangsu Province, and in Lingshui, Hainan Province, in 2002 and in Nanjing in 2003 was taken as LTG indicator. A total of 11 QTL on
chromosomes 2, 5, 7, 8, 11, and 12 were detected in the above three seed production environments. Of these, QTL on
chromosomes 7 and 11 mapped in similar genomic regions in all experiments and the maximum percentage of phenotypic variation explained (PVE) by each QTL was 27.93%, while epistatic interaction had slightly low PVE.

Expression of a Vacuolar Na⁺/H⁺ Antiporter Gene of Alfalfa Enhances Salinity Tolerance in Transgenic Arabidopsis

AN Bao-Yan;LUO Yan;LI Jia-Rui;QIAO Wei-Hua;ZHANG Xian-Sheng;GAO Xin-Qi

Acta Agron Sin. 2008, 34(04):  557-564.  doi:10.3724/SP.J.1006.2008.00557

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Plant Na⁺/H⁺ antiporters play an important role in salt tolerance. An alfalfa (Medicago sativa) full length cDNA (named as MsNHX1) was isolated by RT-PCR according to the homologous region of plant Na⁺/H⁺ antiporter genes. Southern blot analysis revealed that there was a small antiporter gene family in alfalfa genome. Sequence analysis indicated that MsNHX1 shared high homology with other vacuolar Na⁺/H⁺ antiporters. Transient transfection of MsNHX1-GFP fusion gene revealed that MsNHX1 targeted to vacuolar membrane. The transcription of MsNHX1 was up-regulated after high salinity treatment. Furthermore, the expression of MsNHX1 in yeast partly suppressed the salt-sensitive phenotype of yeast Na⁺/H⁺ antiporter mutant, indicating that MsNHX1 was a functional Na⁺/H⁺ antiporter of alfalfa. The physiological analysis revealed that the expression of MsNHX1 in Arabidopsis enhanced the resistance of transgenic plants to salt stress. These results suggest that MsNHX1 is a vacuolar Na⁺/H⁺ antiporter and functions in salt tolerance of plants.

Specific Expression of Cry1A Gene Driven by Cotton arf1 Promoter in Tobacco

GUAN Min;CUI Hong-Zhi;ZHANG Rui;GUO San-Dui

Acta Agron Sin. 2008, 34(04):  565-570.  doi:10.3724/SP.J.1006.2008.00565

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The expression of Bt toxin in certain plant developmental period, certain quantity or certain organ in the transgenic plant is an important study field both in new generation of Bt crops and biosafty of Bt crops. Promoter plays a key role to control foreign gene’s expression feature. Previous study analyzed the function of a promoter, which is cotton ADP-ribosylation factor 1 (arf1) gene’s promoter, cloned in our laboratory. A plant expression vector pGBI121.A1Bt, which contained the Cry1A gene under the control of cotton arf1 promoter and the Ω factor, was constructed. Used as control, another vector pGBI121.4AB, carryies Cry1A gene driven by P2E35S promoter, which is modified CaMV 35S promoter with doubled enhancers and a Ω factor. By agrobacteria mediated transformation, tobacco was transformed by the two kinds of vector respectively. ELISA assay showed that the average expression level of the Cry1A gene in the capsule, capsular hull, petal and leaf of pGBI121.A1Bt transgenic tobacco plants was 1.5, 1.5, 1.4, and 0.3 times of the that of pGBI121.4AB transgenic tobacco plants. The results suggest that arf1 promoter could drive foreign gene expression well in plant propagation organs. Therefore, we think arf1 promoter could be applied in the development of new generation of Bt cotton, which has better cotton bollworm resistant effect for expressing more Bt toxin in cotton boll.

Effect of Allelic Variation at the Glu-1 Loci and 1B/1R Translocation on the Quantity of Gluten Protein Fractions and Pan Bread Making Quality in Common Wheat

TANG Jian-Wei;LIU Jian-Jun;ZHANG Ping-Ping;XIAO Yong-Gui;ZHANG Yong;QU Yan-Ying;HE Zhong-Hu

Acta Agron Sin. 2008, 34(04):  571-577.  doi:10.3724/SP.J.1006.2008.00571

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Composition and quantity of gluten protein fractions play an important role in determining the processing quality in common wheat. Wheat varieties with over-expression of HMW glutenin subunit produced very strong and extensible dough. Thus it is very important to understand the relationship between the quantity of gluten protein fractions and dough properties, and pan bread making quality. In this study, 42 wheat genotypes including newly released high quality cultivars and advanced lines in Northern China Winter Wheat Region and leading cultivars in Shandong province were grown in Jinan in 2005–2006 cropping season. Reversed-phase high-performance liquid chromatography (RP-HPLC) and size-exclusion high-performance liquid chromatography (SE-HPLC) were used to analyze the relationship between the quantity of gluten protein fractions and different storage protein compositions, dough properties, and pan bread making quality. The results showed that Glu-D1 locus had the largest effect on the quantity of gluten protein fractions and pan bread making quality in all loci studied, accounting for 28.5%–71.3% of the variation (P<0.05). According to individual glutenin subunit contribution to the expression quantity of gluten protein fractions and pan bread making quality, different glutenin subunit loci could be ranked as: 1>2*>N at Glu-A1; no significant differences at Glu-B1; and 5+10>2+12>4+12 at Glu-D1. Quantity of HMW-GS was significantly different at various loci (P<0.05), and expression quantity of gluten protein fractions showed broad variation among genotypes with the same HMW-GS composition. It indicated that the difference of gluten expression quantity could be an important factor resulting in quality difference in wheat cultivars. 1B/1R translocation caused a significant decrease in expression quantity of LMW-GS, gluten content and %UPP, and showed poor pan bread making quality. Both desirable protein composition and high expression quantity are needed to be considered for efficiently improving dough quality.

Molecular Tagging and Source Analysis of QTL for Elite Fiber Quality in Upland Cotton

HU Wen-Jing;ZHANG Xiao-Yang;ZHANG Tian-Zhen;GUO Wang-Zhen

Acta Agron Sin. 2008, 34(04):  578-586 .  doi:10.3724/SP.J.1006.2008.00578

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With the development and application of molecular biology technology in recent years, several genetic maps developed from different combinations have been constructed and lots of QTL controlling fiber quality or yield components detected, which makes the breeding procedure more effective, immediate and time-saving. In this paper, both F₂ and F_2:3 populations were constructed using two elite upland cotton (Gossypium hirsutum L.) strains (variety), 7235 and Yumian 1 as parents. Linkage analysis with SSR molecular markers revealed that 80 loci were mapped into 19 linkage groups that covered 1 147.8 cM genetic distance. A total of 36 QTLs were detected by composite interval mapping method, including 6 for fiber length, 8 for fiber strength, 7 for micronaire value, 8 for fiber elongation and 7 for fiber uniformity; and explained 3.4%–14.4%, 5.0%–42.4%, 6.5%–11.7%, 5.1%–19.4%, and 6.9%–14.0% of the corresponding phenotypic variations, respectively. Analysis of QTL distribution indicated that D7, D8, and D9 chromosomes were enriched with QTLs controlling fiber strength in both parents, among them those existed in D7 and D8 chromosomes were closely linked and two QTLs controlling fiber strength located respectively in D7 and D9 chromosomes were in the complete same position, which could be related with that both 7235 and Yumian 1 bear the pedigree of elite fiber accession PD4381. The utilization potential of the QTL of super quality in the pyramiding breeding was also discussed.

Fine Mapping of qBlsr5a, a QTL Controlling Resistance to Bacterial Leaf Streak in Rice

HAN Qing-Dian;CHEN Zhi-Wei;DENG Yun;LAN Tao;GUAN Hua-Zhong;DUAN Yuan-Lin;ZHOU Yuan-Chang;LIN Min-Chuan;WU Wei-Ren

Acta Agron Sin. 2008, 34(04):  587-590.  doi:10.3724/SP.J.1006.2008.00587

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Bacterial leaf steak (BLS) is one of the most destructive diseases in rice. Using a recombinant inbred line population derived from a cross between a highly-resistant variety Acc8558 and a highly-susceptive variety H359, 11 QTLs controlling rice resistance to BLS were previously mapped, among which a QTL on the short arm of chromosome 5 named qBlsr5a had the largest effect. This QTL was further verified and more precisely mapped later. In this study, with Acc8558 as the donor and H359 as the recipient, an near-isogenic line H359-BLSR5a was created by backcross breeding with marker-assisted selection, in which only the QTL qBlsr5a was introgressed from the donor parent. A large F₂ population was constructed by hybridizing the near-isogenic line with H359. By selecting individuals with extreme phenotypes and examining their progeny (F_2:3) lines, individuals with the resistant homozygous genotype at the target QTL in the F₂ population were identified. By genotyping these individuals with SSR markers and performing linkage analysis, qBlsr5a was mapped to an interval between SSR markers RM153 and RM159, covering a range of 2.4 cM or 290 kb.

Comparative Assessment of SSR Allelic Diversity in Wild and Cultivated Rice in China

ZHANG Xiao-Li;Guo Hui;WANG Hai-Gang;LÜ Jian-Zhen;YUAN Xiao-Ping;PENG Suo-Tang;WEI Xing-Hua

Acta Agron Sin. 2008, 34(04):  591-597.  doi:10.3724/SP.J.1006.2008.00591

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Forty-eight SSR markers were used to compare genetic diversity in 288 accessions of common wild rice (O. rufipogon Griff.) and cultivated rice (O. sativa L.) in China. There were 505 alleles at the 48 loci investigated. The average number of alleles per locus (Na) was 10.5 with a range from 5 to 20. Total Nei’s genetic diversity index of Nei per locus (He) varied widely from 0.384 (RM409) to 0.905 (RM206) with an average value of 0.731. By comparison of the genetic changes in Na and He, the genetic di-versity of common wild rice was obviously higher than that of cultivated rice. Na and He of cultivated rice was only about 70.2% and 88.2% of common wide rice, respectively. In cultivated rice, Na of landraces and improved varieties were 65.4% and 53.0% of common wild rice respectively, and Na of improved varieties was 81.1% of landraces. Analysis of molecular variance (AMOVA) indicated that 10.3% of the variation was from differences between species. Using locus-by-locus AMOVA procedure, there were 43 loci with significant differentiation. The highest genetic differentiation was 46.3% (RM427) with a range from 0.7% to 46.3%. A cluster analysis showed japonica was the main trend for most of common wild rice in China. In addition, only a few of accessions from Guangdong and Hainan showed tendency towards indica type.

A MADS-Box Transcription Factor Related to Fertility Conversion in Male Sterile Wheat Lines

ZHOU Lin-Lin;SONG Guo-Qi;LI Hong-Yan;HU Yin-Gang;HE Bei-Ru

Acta Agron Sin. 2008, 34(04):  598-604.  doi:10.3724/SP.J.1006.2008.00598

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Male sterility is one of the major characteristics to be used in heterosis utilization of crops, in which thermo-sensitive or photo-sensitive male sterility is very important for two-line hybridization due to the conversion of their male fertility under special weather conditions. YS type thermo-sensitive male sterile wheat (Triticum astivum L.) lines are applicable for heterosis use in the major wheat production areas of northern China. To investigate the molecular basis of male fertility conversion of YS type thermo-sensitive male sterile wheat lines, we constructed the sterile and fertile suppression subtractive hybridization (SSH) cDNA libraries respectively, using the cDNA of the male sterile or fertile young spikes from the same individual of one YS type thermo-sensitive male sterile wheat line A3017 under controlled male sterile or fertile conditions. Comparing the EST sequences between the two cDNA libraries, an EST (GenBank accession number: 36925702) highly similar to MADS box transcription factor gene was selected from the sterile SSH-cDNA library and used as the probe to search the dbEST. A pair of primers was designed based on the aligned sequence of highly homological EST sequences, and used to detect the expression difference of this gene between male sterile and fertile spikes via Reverse Transcriptase PCR (RT-PCR). The results showed that the expression of this gene in male sterile spikes was much higher than that in fertile spikes. Then the RT-PCR fragment amplified from the male sterile spikes was cloned and sequenced, a cDNA sequence with 666 bp and encoding 160 amino acids was obtained. The cDNA fragment contained the typical K-box domain of MADS-box, and designated as TaMS-MADSbox. The deduced amino acids were 94% similar to WAG (BAC22939), an MADS box transcription factor of wheat. The expression profiles of this MADS-box transcription factor gene in the male-sterile lines and their maintainers of three types of male sterile wheat lines were further analyzed via semi-quantitative RT-PCR. The result showed similar patterns that the expression of the MADS-box transcription factor gene in male-sterile lines was much higher than that in maintainers. It suggests that the expression of TaMS-MADSbox is related to the fertility conversion of male-sterile lines. The spikes are male-sterile under high-level expression of TaMS-MADSbox, while fertile under the low-level expression.

Lodging Resistance Indices and Related QTLs in Soybean

HUANG Zhong-Wen;ZHAO Tuan-Jie;YU De-Yue;CHEN Shou-Yi;GAI Jun-Yi

Acta Agron Sin. 2008, 34(04):  605-611.  doi:10.3724/SP.J.1006.2008.00605

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The used lodging resistance index is lodging score, with 0 as most resistant and 4 as most sensitive. In breeding for lodging resistance, an index more precise than lodging score and independent from the cultivation conditions is expected. In the present study, four kinds of lodging resistance indices, i.e. fresh matter moment (plant height × above ground fresh weight, PF), dry matter moment (plant height × above ground dry weight, PD), fresh weight moment per unit of stem broken strength (PFS), and dry weight moment per unit of stem broken strength (PDS), were designed in two experiments, one with 32 diverse cultivars and one with the RIL population NJRIKY including 184 recombinant inbred lines of the cross (Kefeng 1 × Nannong 1138-2) in 2005 and 2006. Among the four indices, fresh weight moment (PF) designated as lodging potential performed with higher correlation with lodging score, more relevant physical meaning, easier operation of measurement, better stability in various environments and more common QTLs with lodging score than those of the other indices, therefore PF was the best candidate of lodging resistance index to replace lodging score. On the basis of the results, QTL analysis was performed for lodging score and lodging potential. Seven QTLs for lodging score on linkage groups A2, C2, D2, and G explaining 6%–12% of phenotypic variation, but no common one between the two years, were detected. There were seven QTLs for lodging potential on linkage groups B1, C2, and O, explaining 5%-12% phenotypic variation, with the same QTL qPFC2-2 in two years. Between lodging score and lodging po-tential, two QTLs were with same flanking markers, i.e. GMKF059a–satt319 and satt286–A63_1T, and the lodging resistance alleles were mainly contributed from Kefeng 1. Between the two loci, qPFC2-2 was of larger contribution, so its flanking markers can be used in marker-assisted selection for lodging resistance in soybean.

TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY

Effect of Nitrogen and Phosphorus on the Amino Acids in Root Exudates and Grains of Rice during Grain Filling

CHANG Er-Hua;ZHANG Shen-Feng;WANG Zhi-Qin;Wang Xue-Ming;YANG Jian-Chang

Acta Agron Sin. 2008, 34(04):  612-618.  doi:10.3724/SP.J.1006.2008.00612

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Nitrogen (N) and phosphorus (P) play important roles in regulating plant growth and development. The purpose of this study was to investigate how N and P nutrients affect amino acids in the root exudates and grains of rice using two rice cultivars, Yangdao 6 (indica) and Yangjing 9538 (japonica), with five treatments, 0N (without N), 1/2N (1/2 N of the standard Espino nutrition solution), 0P (without P), 1/2P (1/2 P of the standard Espino nutrition solution), and CK (standard Espino nutrition solution) during the grain filling period. The concentrations and components of amino acids in root exudates and grains were measured, and their relations were analyzed. The results showed that the concentration of each amino acid in root exudates decreased gradually with the process in grain-filling. Nitrogen stress (0N) during grain filling significantly reduced concentrations of the each amino acid in root exudates and grains. Phosphorus stress (0P) significantly increased concentrations of acidic and neutral amino acids in root exudates, whereas significantly reduced the contents of total amino acids, essential amino acids, and other amino acids in grains. The concentrations of amino acids in root exudates were significantly and negatively correlated with the relative content of amino acids in grains, and the concentration of alkali amino acids in root exudates was significantly and negatively correlated with 1 000-grain weight. The results suggest that the concentration and components of amino acids in root exudates are closely associ-ated with those in grains and with grain weight. N and P nutrients play a role in regulating the concentrations/contents and com-ponents of amino acids in roots and grains, and by which influence grain yield and nutrient quality of rice.

Analysis of Differential Expression of Proteins in Rice Leaf Sheath during Grain Filling

LI Zhao-Wei;XIONG Jun;LI Zhen-Fang;QI Xiao-Hui;CHEN Hong-Fei;SHAO Cai-Hong;WANG Jing-Yuan;LIANG Yi-Yuan;LIN Wen-Xiong

Acta Agron Sin. 2008, 34(04):  619-626.  doi:10.3724/SP.J.1006.2008.00619

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To reveal the molecular mechanism of metabolism in rice leaf sheath, this study investigated differential expression of proteins in rice leaf sheath of Jinhui 809 cultivar with large panicles and high setting percentage during grain filling by the method of differential proteomics. Twenty-three proteins with obviously different abundance were detected, and eleven of them were identified in function. Those functional proteins were classified into six categories according to their dynamic pattern of expression during grain filling. The first type showed down-regulation during grain filling, such as oxaloacetate decarboxylase alpha subunit. And the second one showed up-regulation at first and then down-regulation, such as ribulose bisphosphate carboxylase small chain and ADP-ribosylation factor 1. The third one was that down-regulated first, and then up and down regulated alternatively, such as auxin response factor, zinc finger, C3HC4 type family protein, vacuolar proton-ATPase, ribulose bisphosphate carboxylase/oxygenase activase. The forth type included rubisco binding-protein alpha subunit, showing an expression pattern of up and down regulation alternatively twice during grain filling. The fifth type performed a decreasing at first and then gradually increasing expression pattern , such as class II metallothionein-like protein 1A and geranylgeranyl diphosphate synthase. The sixth type was protein kinase family protein performing a gradually increasing expression pattern. These six different types of proteins involve in photosynthesis, hormone regulation, substance transportation, resistance response to plant senescence and cell signal diversion in leaf sheath respectively. They regulate the mechanism of sink to source transition together.

Quantitative Analysis on the Effects of High Temperature at Meiosis Stage on Seed-Setting Rate of Rice Florets

SHI Chun-Lin;JIN Zhi-Qing;ZHENG Jian-Chu;TANG Ri-Sheng

Acta Agron Sin. 2008, 34(04):  627-631.  doi:10.3724/SP.J.1006.2008.00627

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High temperature, especially happened at flowering stage and meiosis stage, would cause sterility of rice florets and became one of restricting factors of rice yield. With the global warming, the high temperature events will increase during crop growth process. In order to evaluate the effect of high temperature on yield quantitatively, it is important to quantify the relationship between temperature and seed-setting rate. Previous studies have focused on the above relationship during flowering stage, but litter discussed the relationship during meiosis stage. In this study a controlled experiment during meiosis stage was conducted at Jiangsu Academy of Agricultural Sciences, China with two cultivars, TY559 and HJ1 under six temperature levels (31, 33, 35, 37, 39, and 41℃) and three durations (1, 3, and 5 d). High temperature lasted five hours from 8:40 to 13:40 each day, and natural environment was set as CK. The effect of high temperature on seed setting rate and the quantitative relationship between seed setting rate and temperature were analyzed. The results showed that temperature below 33℃ had no significant effect on seed setting rate, but with the increase of temperature and its duration the seed setting rate decreased gradually. The daily relative seed setting rate could be expressed in terms of temperature with a quadratic equation, and the total effect of high temperature during meiosis stage on relative seed setting rate could be expressed in the product of daily relative seed setting rates. Further, combining the diurnal change of temperature, the quantitative effect factor under the nature diurnal change pattern of temperature was dis-cussed. This study provided a quantitative method for calculating the effect of high temperature at meiosis stage on seed setting rate of rice, and would help to improve high temperature-induced sterility model in rice.

Effect of Shading after Anthesis on Starch Accumulation and Activities of the Related Enzymes in Wheat Grain

LI Wen-Yang;YIN Yan-Ping;YAN Su-Hui;DAI Zhong-Min;LI Yong;LIANG Tai-Bo;GENG Qing-Hui;WANG Zhen-Lin

Acta Agron Sin. 2008, 34(04):  632-640.  doi:10.3724/SP.J.1006.2008.00632

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Low light intensity as a result of cloudy or rainy days often occurs during the grain filling of winter wheat (Triticum aestivum L.) in Huanghuai region of China, largely affecting grain yield and starch accumulation. Many investigators have de-
monstrated the effects of shading on photosynthesis, dry matter accumulation, grain yield and its components of winter wheat. However, there are few reports on the effects of shading on starch synthesis in wheat grain. In the present experiment, two wheat cultivars Jimai 20 and Shannong 1391 were used for the mechanism study on starch synthesis response to shading in grains. The black nets were over the wheat canopy to reduce light intensity to 10% in the early (6–9 d after anthesis, S1) and middle (16–19 d after anthesis, S2) grain filling stages. The starch accumulation, starch granule distribution, and activities of enzymes involved in starch synthesis were examined during grain development of winter wheat. The results showed that shading after anthesis remarkably reduced starch accumulation, and significantly increased the amylose content in ripe grains. The amount of starch accumulation showed an order of control (CK)>S1>S2. Shading significantly increased and reduced the volume percents of A-type starch granule and B-type starch granule, respectively. Logistic simulation and correlation analysis showed that it was mean starch accumulation rate and the starch accumulation rate in actively-increasing period, but not starch accumulation duration affected by shading to reduce grain starch accumulation. The activities of sucrose phosphate synthase (SPS), sucrose synthase (SS) and adnosine diphosphate glucose pyrophosphorylase (AGPase) in shading treatments were significantly lower than those in control. The activities of granule bounded starch synthase (GBSS) and soluble starch synthase (SSS) under shading stress at early grain filling were higher than those in control or no significant difference with those in control. However, the activities of GBSS and SSS under shading stress at middle grain filling were significantly lower than those in control. The results suggested that there are less the substrate for starch accumulation, caused by low activities of SPS, SS, and AGPase in S1 treatment, and both less the substrate and the low activities of starch synthase (GBSS and SSS) in S2 treatment.


Comparisons of Several Nutritional and Cooking Qualities of Grains at Different Grain Positions of Panicle between Two Panicle Types of Japo- nica Rice

CHEN Shu-Qiang;JIN Feng;DONG Dan;LIU Bai-Lin;XUE Jing-Fang;ZHANG Wen-Zhong;XU Zheng-Jin;CHEN Wen-Fu

Acta Agron Sin. 2008, 34(04):  641-652.  doi:10.3724/SP.J.1006.2008.00641

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Nutritional and taste quality are focused in rice (Oryza sativa L.) breeding for grain quality. Panicle type may have certain effect on grain quality traits. However, research in detail on grain quality difference between/within erect and curved panicle rice is not well-documented. The objective of the present study was to characterize the difference in several nutritional and cooking qualities at different seed positions in japonica rice cultivars which differ in panicle type. Three erect and three curved panicle japonica rice cultivars of similar maturity were grown in randomized block design in 2006. After maturity protein content (PC), amylose content (AC), and taste quality (TQ) of milled rice were measured. The results showed that panicle type had considerable influence on PC, AC, and TQ at the different parts of panicle, for erect panicle cultivars, PC and AC increased with the grain position from the upper to the lower parts, while TQ showed reverse trend; for curved panicle ones, PC and AC showed no regular trend, but TQ was the same as that of erect panicle cultivars. In the same panicle, the PC of secondary branches was higher than that of primary branches, while AC and TQ behaved reversely. In the same rachis branches, the 2nd and 3rd grain of secondary branch at lower part had higher PC and lower TQ, the 1st to 6th grains of primary branch at mid and upper part had lower PC and higher TQ, no rule was found for AC at different grain positions of panicle. The difference of referred quality traits at different grain positions in erect panicle was higher than that in curved panicle, resulting from higher grain density in erect panicle. Results from this study will facilitate erect panicle cultivars in rice breeding for quality in Northeast China.

Bending Mechanical Properties of Stalk and Lodging-Resistance of Maize (Zea mays L.)

GOU Ling;ZHAO Ming;HUANG Jian-Jun;ZHANG Bin;LI Tao;SUN Rui

Acta Agron Sin. 2008, 34(04):  653-661.  doi:10.3724/SP.J.1006.2008.00653

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High plant density is one of the cultivation measures for high yield in maize production, but may risk lodging during the growing period. The occurrence of lodging is highly related to stalk mechanical intensity in addition to plant height and stalk diameter. Some investigators have measured the indices of stalk intensity in maize, but we believe that the knowledge on bending properties of maize stalk will give more mechanical explanation to lodging-resistance. In the present experiment, we employed three maize cultivars, Denghai 3719 (high density-tolerant and lodging resistant), Jingke 519 (low density-tolerante and lodging resistant), and Nongda 108 (moderate density-tolerant), and used universal hydraulic test equipment to investigate the Yong’s modulus and the bending strength of stalk under five densities (3.00, 5.25, 7.50, 9.25, and 12.00 × 104 plants ha-1, respectively). The basal 1st to 8th internodes of 3–8 plants from each treatment were sampled at pre-tasselling and dough stages, respectively. The parameters of stem morphologic trait showed thinned internode diameter and longer internode at basal stem accompanying with the increasing of maize planting density in all three cultivars, in which Denghai 3719 had the smallest values (internode diameter and length). The moment of inertia of maize stalk varied among cultivars and among internodes, and close related to internode diameter. The Yong’s modulus and bending strength of maize stalk increased in the process of growth period, but decreased significantly with the increasing of planting density and the rising of internode position. The Yong’s modulus and the stalk bending strength on the average of the 3rd and 5th internodes were 72.32 MPa and 4.05 MPa in Denghai 3719 at pre-tasselling stage, while only 42.31 MPa and 2.80 MPa in Jingke 519 which were the stalk broken thresholds in high densities (7.5–12.0 × 104 plants ha-1). They went up by 100.8% and 129.3% in Denghai 3719 and 59.1% and 105.7% in Jingke 419, respectively at dough stage. The results imply that the probable critical parameters of stalk broken are 40.0 MPa for Yong’s modulus and 2.8 MPa for maximum bending strength at basal internodes at pre-tasselling stage in maize. The Yong’s modulus of stalk was significantly correlated (P<0.01) with the bending strength. While the diameter of internodes was positively correlated (P<0.01) with Yong’s modulus and bending strength of stalk at pre-tasselling stage, but not at dough stage. They were negatively correlated at P<0.01 with field lodging per-centage. The Yong’s modulus could reflect the ability of tolerance to high densities of stalk, and the bending strength of stalk to lodging resistance, however, the diameter of internodes was not a good indicator for evaluating stalk mechanical strength. The bending mechanical properties of different cultivars under different planting densities showed similar trends at pre-tasselling and dough stages, indicating the possibility of selection and evaluation for lodging-resistant maize cultivars at early developmental stage.

Heterosis of Root Growth in Maize (Zea mays L.) Seedling under Water Stress

LI Bo;TIAN Xiao-Li;WANG Gang-Wei;PAN Fei;LI Zhao-Hu

Acta Agron Sin. 2008, 34(04):  662-668.  doi:10.3724/SP.J.1006.2008.00662

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Maize (Zea mays L.), the earliest crop for heterosis application, is highly sensitive to water stress. The root system is one of the important organs contributing to drought tolerance. However, few reports have provided quantitative data on the hybrid vigor in root development of maize, especially on that under water stress. The objective of this study was to investigate the hete- rosis of maize root growth at seedling stage and the effects of water availability on it. Hybrid maize Gaoyou 115 (220 × 1145) and its parents were subjected to three water treatments: 75%, 55%, and 35% of field water-holding capacity, considered as well watered (WW), moderate water stress (MWS), and severe water stress (SWS) respectively. The desired soil water regimes were well prepared at the beginning of the experiment, and kept by weighing. Under WW treatment, substantial midparent heterosis (MPH) and overparent hereosis (OPH) were observed for root dry weight (RDW), root length (RL), and root surface area (SA). MPH for these traits was in the range between 100% and 203%, and OPH between 99% and 189%. MWS clearly reduced the degree of heterosis compared with WW; MPH was in the range between 73% and 108%, and OPH between 55% and 59%. However, SWS arrested hybrid vigor in root growth almost completely. These results indicate that heterosis of root growth in maize seedlings varies with water availability. The maximum heterosis for root growth was obtained in RL with average 155.5% MPH and aver-age 124.2% OPH over WW and MWS. Compared with middle (0.25 mm < root diameter (DA)≤0.45 mm) and coarse (0.45 mm < DA) roots, fine (0.05 mm < DA≤0.20 mm) roots displayed the highest degree of MPH and OPH in absolute RL and SA under WW, MPH for its RL and SA was 265% and 246%, respectively, and OPH 218% and 208%, respectively. For the ratios of RL and SA to the total RL and SA respectively, they only displayed significant and slight MPH, but compared with middle and coarse roots, fine roots (with 21% and 44% of MPH for RL% and SA%, respectively) still had the highest degree of heterosis. Although we still detected significant MPH and OPH for absolute RL and SA regardless of root diameter classes (except for OPH for coarse roots) and significant MPH for the ratios of RL and SA concerning fine roots under MWS, it was obvious that MWS reduced het-erosis of RL and SA, especially for fine roots. MPH values for absolute RL and SA showed about one-fold decreases, and OPH showed more than two-fold decreases. Additionally, absolute RL and SA for fine roots do not reveal heterosis under SWS, but the ratios of RL and SA for them significantly displayed 9% and 16% of MPH, respectively. This suggests that the seedlings of hybrid maize develop more and greater proportion of fine roots than its parents (especially under water stress), which enable them to resist moderate drought better.

Effects of High Temperature Stress on Flowering and Grain-Setting Characteristics for Guodao 6

TAO Long-Xing;TAN Hui-Juan;WANG Xi;CAO Li-Yong;SONG Jian;CHENG Shi-Hua

Acta Agron Sin. 2008, 34(04):  669-674.  doi:10.3724/SP.J.1006.2008.00669

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Worldwide warming climate is causing more and more disadvantages for farming. A better understanding of high temperature stress on rice production is necessary for sustainable agriculture. In present study, eight leading hybrid rice combinations were selected to study the physiological and morphological adaptability to 40℃ air temperature stress. Heat treatment was conducted by 6 h each day from initial heading through 15 days. Guodao 6 and Xieyou 46 showed significant differences in response to high temperature stress during flowering period, and were selected to do further study on their flowering and grain-setting characteristic to high temperature stress. It was observed that Guodao 6 showed a relative stability in grain setting under high temperature stress. This may be associated with its adaptability to heat avoidance, displaying flowering period shortened and “Apical grain superiority” weakened, as well as flowering clock decentralized and the flowering peak value decreased. Daily number of spikelet flowering increased and flowering clock delayed for 2 hours during initial heading period.

Effects of Nitrogen Levels on Photosynthesis and Chlorophyll Fluorescence Characteristics under Drought Stress in Cotton Flowering and Boll- Forming Stage

LIU Rui-Xian;WANG You-Hua;CHEN Bing-Lin;GUO Wen-Qi;ZHOU Zhi-Guo

Acta Agron Sin. 2008, 34(04):  675-683.  doi:10.3724/SP.J.1006.2008.00675

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The flowering and boll-forming stage is the key yield determinant period of upland cotton. Short-duration water stress occurring during this stage significantly reduced cotton development and final productivity. Nitrogen application plays an important role in alleviating the adverse effects of dry soil on plant development. In order to explore effects of nitrogen on cotton photosynthesis under drought stress. The photosynthesis and chlorophyll fluorescence characteristics of cotton with different nitrogen application were examined under developing gradually drought stress during flowering and boll-forming stage. Leaf water potential, soil relative water content, net photosynthetic rate (P_n), stomatal conductance (G_s), and intercellular CO₂ concentration (C_i) were reduced, but the pigment contents of cotton leaf were increased under soil drought stress. The reduced degree of P_n was increased with increasing nitrogen levels. Under drought stress, P_n, G_s, C_i, Chl a content, Chl b content, Chl a+b content. and Car content in 240 kg N ha^-1 treatment was the highest among the three nitrogen levels. Drought stress caused a significant decline in the maximum photochemical efficiency of photosystem II (F_v/F_m), the quantum yield of electron transport (ΦPS II), the electron transport rate (ETR) and the photochemical quenching co-efficient (qP). These changes were accompanied by an increase in both the minimal fluorescence (Fo) and the non-photochemical quenching co-efficient (NPQ). F_v/F_m, ΦPS II, ETR, and qP were higher at 240 kg N ha^-1 level than at 0 and 480 kg N ha^-1 levels. The transpiration (Tr) of cotton was reduced and the temperature of leaf was enhanced under drought. The dry matter of cotton decreased under drought. Nitrogen application increased dry matter weight and augmented the water stress indexes. All results suggest that 240 kg N ha^-1 is the optimal nitrogen application rate under drought, deficient (0 kg N ^ha-1) and excessive (480 kg N ^ha-1) nitrogen application are of disadvantage to photosynthesis and chlorophyll fluorescence characteristics.

Effect of Nitrogen Deficiency on Yield and Photosynthetic Traits of Cytoplasmic Male Sterility Maize

LI Cong-Feng;LIU Peng;WANG Kong-Jun;ZHANG Ji-Wang;DONG Shu-Ting

Acta Agron Sin. 2008, 34(04):  684-689.  doi:10.3724/SP.J.1006.2008.00684

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Male sterility of higher plant is a common phenomena found in many species. Cytoplasmic male sterility (CMS) plays an important role in maize (Zea mays L.) breeding for its advantages of yield and reducing costs. It is reported that CMS maize has a positive effect on yield of single and double hybrids, as well as their homotype hybrids. Normal detasseling and CMS hybrid probably lead to higher yield under stresses, and the increase extent of yield varies with stress degree. Most grain yields of CMS lines are higher than those of their homotype lines, and male sterile plants have different effects with different genotypes. Plant photosynthesis traits have a direct influence to yield. However, the mechanism of increasing yield by male sterility is uncertain. To investigate the effects of low nitrogen after anthesis on grain yield and photosynthetic traits, we conducted a field experiment by low nitrogen treatment in 2004–2005 with two inbred lines, cytoplasmic male sterility (478CMS and Q319CMS) and homotype fertile lines(478 and Q319). The fertilizer was applied at one time before sowing, we sampled at 0, 10, 20, 30, 40 d after anthesis to determine the nitrogen content and the photosynthesis traits at the same time. Grain yield and yield components were measured after maturity. The result showed that compared with their homotype lines (the maintainer lines), CMS lines had higher grain yield with the increase by 11.5%, significantly greater kernel weight and harvest index, but no significant difference in numbers of kernels per panicle. Also, CMS lines maintained higher nitrogen, chlorophyll and soluble protein contents, and larger leaf area index at late growth stage, indicating that CMS maize has a better green-maintaining character, prolonging effective photosynthesis duration and postponing the senescence course of plant. In CMS lines, photosynthetic rate (P_n), intercellular CO₂ concentration (C_i) and stomatal conductance (G_s) were higher at late growth stage obviously, and not sensitive to nitrogen deficiency in soil. Chlorophyll fluorescence parameters such as the actual photochemical efficiency (FPSⅡ), the apparent electron transfer rate (ETR) and the maximal photochemical efficiency (F_v/F_m) of CMS lines were higher than those of their homotype lines. These suggested that CMS lines have great advantages in photosynthesis ability, electron transfer, and light energy transform at late growth stage, and the higher grain yield of CMS lines comes from the common improvement of leaf physiological activity and photosynthetic efficiency in grain filling period.

Effects of Nitrogen Phosphorus Potassium and Water on Lutein in Tobacco (Nicotiana tabacum L.) Leaves

LIU Guo-Shun;CHEN Yi-Qiang;WANG Fang;LING Ai-Fen;XI Hong-Ang

Acta Agron Sin. 2008, 34(04):  690-699.  doi:10.3724/SP.J.1006.2008.00690

Abstract ( 1916 )   PDF (1202KB) ( 1748 )   Save

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As a main component of carotenoid in tobacco leaves, lutein not only plays an important role in protection against light stress, but also produces many important aroma compounds in tobacco including megastigmatrien, β-damascenone, 3-hydroxy-α-ionone, when lutein degraded. A pot experiment with the design of quadric circum-regression was performed to investigate the effects of N, P, K fertilizers and watering on lutein in tobacco leaves. The zero level of four factors was designed as 4, 6, 12 g and 70%, and the intervals as 2, 3, 6 g and 15%, respectively. The results from interaction test indicated that the first order interactions, the second order interaction of (i) N, P and water, (ii) P, K and water, the third order interaction were all significant, and interaction between N and P, N and K, P and K, P and soil water, K and soil water content was synergistic. But there existed a critical value in the interaction of N and water, when soil water content was lower than the critical value, the interaction between them was synergistic, otherwise it was antagonistic. The second order interaction analysis showed that K and soil water content were more important than P for increasing lutein content in tobacco leaves. It suggested that the proper ratio of N, P, K fertilizers, and watering could increase the lutein content. More P and optimal soil relative water content would increase the lutein content when nitrogen was deficient. More N and K and reasonable watering could increase the lutein content at the lower P level. More N, P, and K could compensate the deficiency of relative soil water content. The results showed that the lutein content accumulated significantly at the high N (6 g pot^-1), high K (18 g pot^-1 K₂O), moderate P with the ratio of N:P₂O₅:K₂O at 1:1.3:3.1, as well as optimal watering maintaining the relative soil water content of 74.3%–79.5%.

RESEARCH NOTES

Establishment of Candidate Core Collection in Chinese Mungbean Germplasm Resources

LIU Chang-You;WANG Su-Hua;WANG Li-Xia;SUN Lei;MEI Li;XU Ning;CHENG Xu-Zhen

Acta Agron Sin. 2008, 34(04):  700-705.  doi:10.3724/SP.J.1006.2008.00700

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Mungbean (Vigna radiate) is planted extensively in China, and there are abundant Chinese mungbean germplasm resources. In order to strengthen the preservation, research and utilization of Chinese mungbean germplasm resources, we established the pre-core collections of mungbean germplasm. In this study, 5 072 mungbean germplasm resources were selected as material. Based on 14 agronomic traits, 13 sampling strategies were used, which consisted of 2 stratification methods, 3 sampling number determination methods and 2 individual selection methods. The criteria against whole collection included mean similarity coefficient, coincidence of traits, mean CV of quantitive traits, mean Shannon index. The results indicated that selection based on clustering was better than random selection, stratification according to traits was better than that according to geographical distribution, genetic diversity-dependent strategy was better than square root and proportion strategies in determination of sampling number. Finally, an optimal strategy was set by stratification according to traits, determination of the sampling number with genetic diversity-dependent strategy, and then selecting sample by clusters. By using this strategy, a pre-core collection of Chinese mungbean germplam with a total of 719 accessions was established, carrying 100% phenotypic genetic diversity of the whole collection.

Effect of Nitrogen Application and Planting Pattern on N and P Absorption and Use in Maize-Peanut Intercropping System

JIAO Nian-Yuan;NING Tang-Yuan;ZHAO Chun;HOU Lian-Tao; LI Zeng-Jia;LI You-Jun;FU Guo-Zhan;HAN Bin


Acta Agron Sin. 2008, 34(04):  706-712.  doi:10.3724/SP.J.1006.2008.00706

Abstract ( 2474 )   PDF (473KB) ( 1845 )   Save

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A field experiment was carried out for revealing the effects of nitrogen application and planting pattern on yield, biomass, N and P absorption, protein yield of maize (Zea mays L.)-peanut (Arachis hypogaea L.) intercropping system in 2004 and 2005. The results showed that the yield, N and P absorption of intercropping maize increased significantly, however, the yield and N absorption of intercropping peanut was reduced in the intercropping system, compared with monocropping maize or peanut respectively. The 2-row maize and 4-row peanut pattern (2:4 pattern) showed higher (P<0.01) values than the 2-row maize and 8-row peanut pattern (2:8 pattern) in yield, biomass, protein yield, N and P fertilizer absorption efficiencies, N and P use efficiencies of intercropping system, and higher (P<0.01) values than the two monocropping systems in N and P absorption efficiencies. Both the land equivalent ratio for yield (LER) and land equivalent ratio for protein yield (PLER) in 2:4 pattern were above 1, and the land use ratio enhanced by 8%–17%, implying obvious intercropping dominance. Compared with zero N application, nitrogen fertilizer increased yield and protein yield of maize and peanut in the intercropping system by promoting the accumulation and absorption of N and P, enhancing P use efficiency, but the intercropping dominance was weakened with the increase of nitrogen fertilizer.

Clone and Quantitative Analysis by Real-Time RT-PCR of Photoperiod Sensitive Gene Hd6-Like in Maize

LI Si -Yuan;CHEN Xiao;WANG Xin-Tao;CHEN Yan-Hui

Acta Agron Sin. 2008, 34(04):  713-717.  doi:10.3724/SP.J.1006.2008.00713

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Hd6 gene plays an important role in photoperiod sensitive phenomenon in rice (Oryza sativa L.). In the present study, a Hd6-like gene was cloned by RT-PCR and rapid amplification of cDNA ends (RACE) using a photosensitive tropical maize (Zea mays L.) inbred line CML288. A predicated 999-bp open reading frame was detected in the cloned sequence, which encoded 332 amino acids. By BLAST analysis, we found the gene sequence shared a high similarity with a gene encoding protein kinase CK2 in maize. The amino acid sequence contained two CK2 activity domains, one ATP binding site, one basic stretch (NLS), one N terminal domain, a putative serine/thereonine protein kinase active site, and showed a high homologization with that of protein kinase CK2α in maize, wheat, rice and Arabidopsis. We established fluorescence quantitative RT-PCR system with CML288, and studied the expression of Hd6-like in shoot apical meristem (SAM) and leaf under long day and short day conditions between 5-leaf and 9-leaf stages. We found that Hd6-like gene expressed both in SAM and leaf of CML288. Under the short day treatment, it expressed higher in SAM than in leaf from 6-leaf to 8-leaf stages with the highest expression level at 7-leaf stage. Under the long day treatment, the expression level fell down suddenly at 6-leaf stage in SAM with the peak at 9-leaf stage in leaf. Our results suggest that Hd6-like gene encodes protein kinase CK2α that closely relates to photoperiod-sensitive, and may function in regulating photoperiod sensitivity in maize.

Carbon and Nitrogen Metabolism and Nitrogen Use Efficiency in Summer Maize under Different Planting Densities

LÜ Li-Hua;TAO Hong-Bin;WANG Pu;LIU Ming;ZHAO Ming;WANG Run-Zheng

Acta Agron Sin. 2008, 34(04):  718-723.  doi:10.3724/SP.J.1006.2008.00718

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We conducted a field experiment to obtain high yield and high recovery of N fertilizer simultaneously through regulating carbon and nitrogen metabolism under suitable planting density in 2006. The main results showed that plants grew well under low or medium densities [9.75×104 (D_1-1) and 11.25×104 (D_1-2) plants ha-1 for CF008; 8.25×10⁴ (D_2-1) and 9.75×10⁴ (D_2-2) plants ha^-1 for Zhengdan 958; and 6.75×10⁴ (D_3-1) and 8.25×10⁴ (D_3-2) plants ha^-1 for Jinhai 5]. Although C and N accumulation in stem/sheath and leaf at silking stage and C and N translocation rate were higher under medium or high density than under low density, grain yield, N uptake efficiency, N use efficiency, and recovery of N fertilizer were significantly higher under low or medium densities. N accumulation in shoots before silking was higher under medium or high density than under low density, N in shoot accumulation at maturity and N in grain were higher under low or medium density. Hence N accumulation in shoot after silking stage was important for grain N accumulation. We also obtained some quantitative criteria based on the research in Wuqiao area: for the three varieties of maize, grain yield was 10 262–11 461 kg ha^-1, recovery of N fertilizer was 23.00%–34.11% under low or medium densities.

Genetic Analysis on Amylose Content of Japonica Hybrid Rice in Different Environments

LÜ Wen-Yan;WU Cui;CHENG Hai-Tao;SHAO Guo-Jun;CAO Ping;MA Lian-Ju;CUI Xin-Fu;YIN Chang-Bin;XU Xing-Wei

Acta Agron Sin. 2008, 34(04):  724-728.  doi:10.3724/SP.J.1006.2008.00724

Abstract ( 2010 )   PDF (352KB) ( 1568 )   Save

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A genetic model for triploid endosperm including endosperm effect, cytoplasmic effect, and maternal effect was used to analyze the amylose content (AC) of F2, F3 seeds and their parents derived from 5×5 incomplete diallel cross of japonica three lines rice, in different years, panicle positions, and two environments. The results showed that in the two environments, AC was controlled by genotype, with predominant endosperm additive effects. With panicle position as environmental factor, significant cytoplasmic variance (V_C) could be detected; for the interaction effect variances, direct dominant × environment variance (V_DE) was primary and cytoplasmic × environment variance (V_CE) was secondary. According to the genetic prediction of interaction effects, V_CE was the biggest for different panicle positions in most cultivars, and cytoplasmic × environment effect caused AC decrease in the grains of middle and upper panicle positions and increase in grains of lower panicle position in CMS lines which had opposite performances to restorer lines. With year as environment factor, V_C was not significant; maternal dominant × environment variance (V_Dm) was the main component of interaction variance.