Table of Content

12 December 2006, Volume 32 Issue 12

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ORIGINAL PAPERS

Development of a Fingerprinting Database and Assembling an SSR Reference Kit for Genetic Diversity Analysis of Wheat

LI Gen-Ying;Susanne Dreisigacker;Marilyn L. Warburton;XIA Xian-Chun;HE Zhong-Hu;SUN Qi-Xin

Acta Agron Sin. 2006, 32(12):  1771-1778. 

Abstract ( 2265 )   PDF (573KB) ( 1419 )   Save

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Understanding of the current and expanded genetic diversity is very important for raising the yield of wheat. Genetic diversity based on molecular markers has been studied in plants for over thirty decades. SSR is the currently most popular marker system in wheat. In order to utilize the diversity held in NARS (National Agricultural Research Station) and CGIAR (Consultative Group on International Agricultural Research) germplasm collections, one of the GCP’s (Generation Challenge Program) premier capacity building activities is to build databases that contain traditional and molecular data on germplasm so that scientists all over the world can access information with relevance to their region on traits, genes, and sequences. In the present study, a fingerprinting database was established containing 134 SSR primers and 2 457 wheat genotypes with the data from CIMMYT and three collaborators: ICARDA, Agropolis, and CAAS. On the base of the database, a SSR reference kit for wheat genetic diversity analysis was developed, which will facilitate the use of this data in new projects and cross-laboratory comparisons. In total, 46 SSR primers with comparatively high polymorphism were selected as the reference markers to constitute the standard allele kit, 334 genotypes fingerprinted within the GCP tier 1 project “Genotyping a composite germplasm set in wheat” were chosen to represent the SSR allele kit consisting of 794 alleles amplified by 46 SSR markers. Genotypes were originally selected and DNA extracted by CIMMYT and 3 additional collaborators: ICARDA, Agropolis, and CAAS. These 334 genotypes, when taken as a group, amplify every allele seen for the wheat genotypes for all the 46 SSRs. The Genotypes were originally amplified with 26 SSRs at CIMMYT, with 8 SSRs at INRA, France, and with 12 SSRs at CAAS. Genotypes were amplified with all SSRs at CIMMYT again to confirm the results. For reamplification at CIMMYT, forward primers were labeled at the 5’ end with either one of three phosphoramidite fluorescent dyes 6-carboxyflouresein (6-Fam), tetrachloro-6-carboxyflouresein (Tet) or hexachloro-6- carboxyflouresein (Hex). PCR-reactions were carried out in an MJ-Research thermocycler model PTC225. Amplification products were separated on an ABI-Prism SequencerTM377 using 4.5% polyacrylamide denaturing gels. Fragment sizes were calculated semi-automatically with the computer software GeneScan 3.1 by comparing to fragments of an internal size standard (GeneScan 350 or 500) labeled with N,N,N,N, -tetramethyl-6-carboxyrhodamine (Tamra). GeneScan fragments were assigned to alleles using the category function of the software Genotyper 2.1. The two genotypes, Opata and Synthetic were run in each gel as controls.
Finally, a SSR reference kit was assembled which includes 46 pairs of SSR primers, protocols (PCR condition, detection of polymorphisms, etc), description of polymorphism in the reference samples, reference DNA samples for a complete range of repeatable 592 alleles, methods for comparing new to preexisting data, and classification of various genotypes. The database and the reference kit will provide a powerful tool for genetic diversity studies of wheat germplasm worldwide.

Photosynthetic Characteristics and Heterosis in Transgenic Hybrid Rice with Maize Phosphoenolpyruvate Carboxylase (pepc) Gene by MAS

LI Ji-Hang;XIANG Xun-Chao;HE Li-Bin;ZHANG Kai-Zheng;LI Ping

Acta Agron Sin. 2006, 32(12):  1779-1787. 

Abstract ( 1980 )   PDF (615KB) ( 974 )   Save

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Posterity materials carrying maize pepc gene has been successfully applied into marker-assisted selection (MAS) by using specific primer of maize pepc gene, and the improved Shuhui881 with pepc gene has been obtained. The improved Shuhui 881 was similar to its backcross pa

Resistance to Fusarium Head Blight and Deoxynivalenol Accumulation and Allele Variation of Related SSR Markers in Wheat

ZHANG Kai-Ming;MA Hong-Xiang;LU Wei-Zhong;CAI Zhi-Xiang;CHEN Huai-Gu;YUAN Sheng

Acta Agron Sin. 2006, 32(12):  1788-1795. 

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Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe, is an important wheat disease world-wide. Negative effects of the disease include not only reduction of grain yield quality, but also contamination with deoxynivalenol (DON) resulting in potential toxicity to human and livestock. Developing the cultivars with FHB resistance is an effective measure to control the disease. Ten cultivars selected from the breeding program for FHB resistance in China were employed in the study for evaluating the resistance to FHB and DON accumulation by using different isolates and inoculation methods. In comparing with susceptible control Ningmai 6 and Annong 8455, the ten cultivars were classified to three groups with different resistance to FHB, including high resistant group (Wangshuibai, Sumai 3, Nobeokoubozu and Fan 60096), moderate resistant group (Fanshanxiaomai, Wenzhouhongheshang, Shinchunaga, Yangmai 158 and Zhen 7459) and susceptible cultivar (Frontana). The DON contents of all of them except Frontana were lower than 3 mg/kg. There were significant correlations between different isolates and inoculation methods for the scabbed spikelet rate and DON content. The scabbed spikelet rate was also significantly correlated to DON content in the same isolate and inoculation method. The selective cultivars were genotyped with SSR markers linked to FHB resistance QTL on chromosomes 2D, 3B, 4B, 5A and 6B identified previously. The SSR markers except GWM133 from 4B chromosome had PIC values of 0.14 to 0.85 and detected 2 to 8 alleles among 13 cultivars. The haplotype showed the same allele of related SSR on chromosome 3B was shared by Nobeokabouzu and Wangshuibai. Yangmai 158 and Shinchunaga had similar SSR alleles to Wuhan 1 on chromosomes 2D and 4B, respectively. Most alleles from Fanshanxiaomai were the same as those from Sumai 3 or Wangshuibai. Most alleles of SSR related to QTL on 2D from Fan 60096 were similar to those from Wuhan 1. However, only one or two alleles in Zhenmai 7459 and Wengzhouhongheshang were the same as those of reported SSR markers associated with FHB resistance. The resistances in such cultivars are most likely derived from independent origin instead of Sumai 3, Wangshuibai and Wuhan 1.

Gliadin Composition and Their Effects on Quality Properties in Spring Wheat

ZHANG Ping-Ping;CHEN Dong-Sheng;ZHANG Yong;XIA Xian-Chun;HE Zhong-Hu

Acta Agron Sin. 2006, 32(12):  1796-1801. 

Abstract ( 1916 )   PDF (424KB) ( 1117 )   Save

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Gliadin composition affects processing quality in bread wheat. CIMMYT and Australian germplasms have made a great contribution to improving yield and quality for Chinese spring wheat, so thirty-three spring wheat (Triticum aestivum L.) genotypes originated from CIMMYT, Australia and China were grown under four environments in 2003 and 2004. The flour sample was separated and quantified by reverse-phase high-performance liquid chromatography method in order to understand the composition of gliadin and the effects on quality properties in spring wheat. The results showed that significant variation in total gliadin and gliadin subgroups were observed among genotypes and environments. Within the subgroups, the α/β-type gliadins were generally presented the greatest amount (43.12%–50.87%), the γ-type gliadins content were the middle (32.71%–43.14%), and the ω-type gliadins content at lower levels (11.89%–21.58%). 1BL/1RS translocation affects the composition and the content of gliadin. High proportion of ω-type gliadins (17.44%–21.58%) was presented in 1B/1R translocation, however, no significant difference was observed on the amount of α/β-type gliadins between the 1B/1R translocation and the non-translocation genotypes. The amounts of total gliadin and the gliadin subgroups were significantly correlated with the protein content in flour of both the translocation and non-translocation lines, while weakly correlated with sedimentation volume, development time, stability time, extensibility and maximum resistance. It is likely that glutenin might play more important role in determining processing quality. In the translocation lines, ω, γ1 and γ-type gliadins had significantly positive correlation with sedimentation volume. Total gliadin, γ2 and γ-type gliadins had significantly positive correlation with dough development time, while ω and γ-gliadins had significantly negative correlation with dough extensibility.

Effects of Nitrogen Rate on Assimilate Transportation to Underground at Different Maize Growing Stages

YANG Lan-Fang;CAI Zu-Cong;QI Shi-Hua

Acta Agron Sin. 2006, 32(12):  1802-1808. 

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Carbon transported to underground is an important source of soil organic matter and affects on the availability of soil nutrient and activity of soil microbe, but its allocation has been rarely studied in China. The soil pot experiment with two nitrogen rates (150 and 300 mg N·kg^-1) at different maize (Zea mays L.) growth stages was conducted. Carbon dioxides released from soil respiration were sampled by the static chamber method and measured by gas chromatography. The results showed that the aboveground biomass, assimilated carbon, total biomass and net assimilated carbon were significantly higher under high nitrogen rate than under low nitrogen rate at flowering and ripening stages, which indicated that the soil in this experiment was short of nitrogen. Carbon transported to underground in maize accounted for 25%–39% of net assimilated carbon and decreased with the growing process of time. Root carbon accounted from 6% to 21% of the net assimilated carbon and was lower at a high nitrogen rate than at a lower nitrogen rate, and also decreased with the growth process of time. The mounts of carbon respired in the rhizosphere and converted into soil organic matter were 11%–14% and 6%–8% of the net assimilated carbon, but they did not change significantly with the growing process of time and nitrogen rates. The quantity of rhizospheric respiration carbon was significantly higher in high nitrogen treatment than in low nitrogen treatment at flowering and ripening stages. Root carbon, rhizospheric respiration carbon and soil organic carbon derived from assimilation were 27%–53%, 31%–53% and 14%–22% of the carbon transported to underground, respectively. The ratio of root carbon to the carbon transported to underground was higher in lower nitrogen treatment and at the stages of trumpeting>flowering>ripening, but the ratio of rhizospheric respiration carbon to carbon transported to underground was lower at lower nitrogen treatment and at trumpeting<flowering<ripening stages. The increment of soil organic carbon was higher at ripening stage than at trumpeting and flowering stages, and in high nitrogen treatment than in lower nitrogen treatment, suggesting that maize growth and N application accelerated the function of soil as a carbon pool. It was concluded that assimilate produced by maize was mainly transported underground during early growth stage and mainly accumulated in aboveground parts during the late growth period. The carbon transported to underground was used for root growth during the early growth stage and for rhizoshperic respiration during late growth period. The increase of nitrogen rate increased the quantity of rhizospheric respiration carbon during the middle and late maize growth periods but did not change the contribution of rhizospheric carbon to net assimilated carbon. The shortage of nitrogen increased the allocation from net assimilated carbon and the carbon transported to underground to roots, but decreased the rhizospheric respiration from carbon transported to underground. Therefore, the use efficiency of assimilated carbon was high under the lower nitrogen treatment. In summary, maize adapted the stress of low nitrogen by increasing the root growth relatively and enhancing the use efficiency of carbon transported to underground.

Single Nucleotide Polymorphism of TaMyb2-Ⅱ Gene in Common Wheat (Triticum aestivum L.) and Its Relatives

WANG Ai-Ping;MAO Xin-Guo;JING Rui-Lian;CHANG Xiao-Ping;YANG Wu-De

Acta Agron Sin. 2006, 32(12):  1809-1816. 

Abstract ( 2112 )   PDF (578KB) ( 998 )   Save

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Drought is one of the major elements affecting the yield of wheat, one of the most important crops in arid and semi-arid areaes. Mining pivotal drought-resistant genes and probing their polymorphisms are a feasible approach to decipher crops’ drought resistance. The genes involved in drought resistance are classified into two classifications, functional genes and regulatory genes, based on their functions responding to water deficient. Much attention has been paid to regulatory genes because of their crucial roles in drought resistance. AtMyb2 regulates the expression of dehydration-responsive genes rd22 and AtADH1 in plants. Recent studies indicate that TaMyb2 is involved in response to water stress in common wheat, but whether its polymorphisms associated with drought resistance is still unclear. To probe the polymorphisms of TaMyb2 gene and uncover their functions in drought resistance, a total of fifty-six accessions, including thirty-nine common wheat cultivars with different drought resistance, five species with A genome including three T. urartu, one T. monococcum and one T. boeoticum, four Aegilops. speltoides, six Ae. tauschii and two tetraploid wheat species, were selected to perform the research. The PCR amplification showed that TaMyb2 was detectable in all accessions except A genome species. Based on the genomic sequences, TaMyb2 was classified into 3 types named as TaMyb2-Ⅰ, TaMyb2-Ⅱ and TaMyb2-Ⅲ, respectively. The full-length sequence of TaMyb-Ⅱ geneomic DNA was 1 606 bp. Twenty-six SNPs (single nucleotide polymorphism) and eight InDels (insertion-deletion) were identified in 77 088 bp nucleotide acid sequence of forty-eight accessions, and the frequencies of SNP and InDel were 1/2 965 bp and 1/9 636 bp, respectively. The frequency of SNP in coding region (π=0.00055) of TaMyb-Ⅱ was lower than that in noncoding region (π=0.00185), the ratio of Ka/Ks was 0.32 which seemed to suggest TaMyb2-Ⅱ suffered artificial selection pressure and was very conservative. Phylogenetic analysis demonstrated that the relationship between Ae. tauschii and common wheat was much closer than that between Ae. speltoides and common wheat. Eighteen haplotypes were detected in forty-eight accessions, in which haplotype 2, 3, 5, 6, 8 and 9 were common wheat cultivars with drought resistance, which indicated that these haplotypes might relate to the drought resistance of common wheat.

Genetic Variation in Photosynthetic Characteristics and Photosynthetic Nitrogen Use Efficiency in Tropical Rice

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

Acta Agron Sin. 2006, 32(12):  1817-1822. 

Abstract ( 1974 )   PDF (469KB) ( 1157 )   Save

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Photosynthetic characteristics are considered to be significant in nitrogen use efficiency (NUE) in view of their close associations with dry matter production and grain yield in cereal crops. Photosynthetic nitrogen use efficiency (PNUE) and photosynthetic characteristics were investigated using six tropical rice (Oryza sativa L.) genotypes including two indica inbreds, two indica hybrids, and two NPT (new plant type) lines under field-grown conditions. The objectives of this study were to compare genotypic variations in agronomic efficiency (AE), PNUE, and related leaf parameters and their correlations among six rice genotypes. The results indicated that net photosynthetic rate (P_n) was higher for NPT lines than for indica inbreds, while it was mediate for indica hybrids. Variations were observed in stomatal conductance (G_s), inter CO₂ concentration (C_i), transpiration rate (T_r), and the ratio of C_i to G_s among all rice genotypes. Differences in leaf nitrogen concentration (N%) and specific leaf weight (SLW) were also found among all genotypes. The P_n per Chlorophyll unit (P_n/Chl) was lower in indica inbreds than in NPT lines while indica hybrids appeared to be middle types. There was a significantly positive correlation between P_n and leaf N content per unit leaf area (Na). Generally, both partial factor productivity of applied N (PFP) and AE of indica hybrids were higher than those of both NPT lines and indica inbreds. However, the lowest PFP and AE were observed in PSBRc18 and IR72903-121-2-1-2, respectively. PNUE was positively and significantly correlated with AE in all genotypes, suggesting that the PNUE at reproductive growth stage of rice might be a good indicator for NUE and could be utilized in evaluating genotypes with high NUE in rice.

QTL Mapping for Fat and Fatty Acid Composition Contents in Soybean

ZHENG Yong-Zhan;GAI Jun-Yi;LU Wei-Guo;LI Wei-Dong;ZHOU Rui-Bao;TIAN Shao-Jun

Acta Agron Sin. 2006, 32(12):  1823-1830. 

Abstract ( 2045 )   PDF (596KB) ( 1091 )   Save

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Genetic improvement of fat and fatty acid composition content of soybean seed is interesting to both farmers and processors. The objective of the present study was to aim at constructing a genetic linkage map and mapping QTLs conferring fat and fatty acid composition contents in soybean. The mapping population with 114 BC1F1 plants of the soybean backcross (Essex×ZDD2315)×ZDD2315 was established and tested for their genetic variation, and then used to construct a genetic linkage map by using MAPMAKER 3.0. The genetic linkage map contained 250 SSR markers and one morphological marker, spanning 25 linkage groups (LG) at a total distance of 2 963.5 cM. Each LG contained 2 to 20 markers, with average distance being about 11.8 cM. The methods of composite interval mapping (CIM) and multiple interval mapping (MIM) of Win QTL Cartographer Version 2.5 were used for QTL mapping. With CIM, 18 QTLs conferring the contents of fat and fatty acid composition in soybean seed were mapped on nine LGs, i.e. B2, C1, D1b-1, D2, E, H-1, I, L and N-1, explaining 8.2%–39.3% of the total phenotypic variation, while with MIM nine QTLs were detected on six LGs, i.e. B2, C1, D1b-1, D2, H-1 and N-1, explaining 9.6%–34.5% of the total phenotypic variation. Of which seven QTLs, i.e. fat-1, pal-1, st-1, ole-1, lin-1, lin-4 and lio-2, were located on the same regions as that under CIM, while the other two, i.e. ole-4 and lin-5, were close to those under CIM. The other nine QTLs detected with CIM, but not common with MIM, need to be further verified. The number of major QTLs with large effect conferring the contents of fat and fatty acids appeared not as many as expected, while the minor QTLs with small effect accounted for a certain amount of the variation. Therefore, both major and minor QTLs should be considered in the improvement of fat quantity and quality in soybean seeds.

Dynamic Simulation of Rice Canopy Structure

SHI Chun-Lin;ZHU Yan;CAO Wei-Xing;JIN Zhi-Qing

Acta Agron Sin. 2006, 32(12):  1831-1835. 

Abstract ( 1966 )   PDF (411KB) ( 1040 )   Save

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Simulating crop growth visually on computer can help readers to better understand crop growth pattern and analyze the relationship between architecture and function. Some architecture models were developed to simulate development of crops in a given time interval, such as leaf age and growth unit. Most of them didn’t discuss the organ elongation processes and daily architecture change. So in order to realize more accurate and delicate crop growth, it is important to develop more applicable models to describe the dynamic change of crop architecture.
On the basis of rice biological laws and field experiments, combined with the output of rice growth model, a general organ elongation model and structural model for rice were developed. Firstly, growth unit, containing internode and its adjacent leaf or ear, was used to describe topological structure of rice plant. Then, with logistic curve for simulating organ elongation and according to the relationship of organ elongation and leaf age, that is, synchronous emerging among the nth leaf blade, the n－1^th leaf sheath and the internode between n－2^th and n－3^th leaf, a dynamical structural model of rice plant was developed utilizing daily output of growth model and leaf age model. The model could give initial elongation GDD, elongation duration in degree days and curve parameters for each organ. So plant architecture could be simulated at any GDD with geometrical parameters of organs. The model was validated with the data from field experiments. The results showed that the model could well simulate plant architecture and organ elongation of rice with RMSE 0.284 cm, applicable to different varieties and environments. Finally using L-system to describe and simulate plant structure, morphological representation of rice plant and canopy at seedling, elongation and anthesis stages was realized.
Combined with the output of rice growth model, a general model was developed to simulate the daily architecture change in rice canopy. The model could offer more accurate and delicate rice growth visually.

Wheat cSNP Mining Based on Full-Length cDNA Sequences

MAO Xin-Guo;TANG Ji-Feng;ZHOU Rong-Hua;JING Rui-Lian;JIA Ji-Zeng

Acta Agron Sin. 2006, 32(12):  1836-1840. 

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Single nucleotide polymorphism (SNP), the third generation molecular marker, is a research focus because of its characteristics of large amount, high stability, wide distribution, easy, high-throughput detection and wide application. Most SNP mining methods were based on the amplification of target regions, except RFLP. Few applications of high-throughput SNP mining methods were reported in common wheat (Triticum aestivum) SNP detection because of its hexaploid, huge genome and high homologous among A, B and D genomes. The dbEST of wheat in GenBank is an important resource to mining SNP with bioinformatic methods, and the full-length cDNA libraries, which constructed with wheat’s three genome donor species seedlings, provide the chance to mine wheat genome specific cSNP candidates.
More than 5 000 clones, from A, S and D genomes’ full-length cDNA libraries, were randomly sequenced, and 2 467 singlets were obtained, thereunto, 990 from A genome, 737 from S genome and 740 from D genome. Using these singlets as origin templates, we “fished out” 1 296 SNP with AutoSNP program from the wheat dbEST in GenBank and developed an effective method to mine wheat cSNP. Among these SNP, 397 were from A genome, 322 from S genome and 420 from D genome. The common SNP of A and D genomes were 154. The SNP shared by A and S, S and D, A, S and D was only 1 respectively, which seemed to indicate that the relationship of A and D genomes was much closer among wheat three genomes according to the principle of SNP mining.
Among the 1296 SNP, eighty-two were InDel , which accounted for 6.25% of all the sequence variations, and most of them were single-base InDel (64.20%), a small part of them were 2–5 base InDel (30.86%), and only very few InDels (4.94%), whose size were more than 5 bases. The analysis results indicated that the frequencies of SNP in the three genomes were different, that was 0.98‰ in A genome, 0.68‰ in S genome and 1.54‰ in D genome, and the average frequency of the three genome was 0.914‰, which was closer with that of soybean (0.97‰), yet much lower than that of maize (6.3‰). Additionally, the ratio of transition/transversion (Ts/Tv) of the three genome were different either, the highest (1.404) was in D genome, the second in A genome (1.196) and the lowest in S genome (1.033), and the average ratio of A, S and D genomes was 1.306, which was much closer with that of maize (1.53) and soybean (1.08), yet far from that of human, mouse and fruit fly.

Obtainment of Transgenic Soybean Plants with Chitinase and Ribosome Inactivating Protein Genes and Their Resistance Identification

GUO Yu-Shuang;ZHANG Yan-Ju;ZHU Yan-Ming;LI Jie;BAI Xi;ZHANG Shu-Zhen;WU Shu-Yin;LI Hai-Yan

Acta Agron Sin. 2006, 32(12):  1841-1847. 

Abstract ( 2035 )   PDF (1501KB) ( 973 )   Save

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Soybean is one of the most important sources of edible oil and protein in the world. However, it suffers from many kinds of fungal diseases, such as frogeye leaf spot (Cercospora sojina) and soybean Phytophora root rot (Phytophthora megasperma Drechs). Fungal disease is a major limiting factor in soybean production. The fungal disease can be effectively controlled by breeding plant cultivars with genetic transformation. Recently bean chitinase gene (chi), barley ribosome-inactivating protein gene (rip) and β-1,3-glucan have been successfully introduced to several plant species and achieved increasing resistance to several fungal diseases. In this study, plant expression vector containing bivalent fungi-resistance gene chi and rip was constructed and these two genes were transferred into four main soybean cultivars in Northeast China by Agrobacterium-mediated transformation. The identification of T₀ regenerated plants was determined by PCR and Southern blot analysis, transgenic soybean co-integrated the two anti-fungal protein genes were obtained, the transformation frequency was 0.5%. Four T₂ Bivalent transgenic soybean lines G0421, G0422, G0423 and G0424 were obtained and the resistance to P. megasperma and C. sojina of the four lines were characterized. Comparing to the non-transgenic type which was sensitive to P. megasperma, G0421, G0422, G0423 were resistant and G0424 was moderately resistant to P. megasperma. All the four lines were resistant to C. sojina while the non-transgenic type is moderately resistant to C. sojina. PCR amplification demonstrated that the T₂ bivalent transgenic soybean lines contained the two transferred genes. RT-PCR analysis showed that both of the two transferred genes expressed in the transgenic soybean lines. These transgenic soybean lines with increasing resistance to P. megasperma and C.sojina will be useful in soybean resistance breeding.

Genetic Variation in Sixty-Four Maize Inbred Lines in Relation to Maize Rough Dwarf Virus

CHEN Yong-Kun;LI Xin-Hai;XIAO Mu-Ji;LI Ming-Shun;YUAN Sen-Xing;WANG Xiang-Dong;ZHANG Shi-Huang

Acta Agron Sin. 2006, 32(12):  1848-1854. 

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Maize rough dwarf virus (MRDV) is one of the most important diseases in maize production in China. In this study, we characterized the genetic diversity in 64 maize inbred lines in relation to MRDV. Sixty-four inbred lines were evaluated for reaction to MRDV under field conditions during 2003 and 2004 at Linfen, Shanxi Province, China. The randomized complete block design in the filed was used with 2 repetitions. The inbred lines were grown in 1-row plots, and the rows were 5 m long each and spaced 0.6 m apart with 17 holes per row and 2 seedlings per hole. At mature stage, the total number of the plants and the number of the diseased plants and the diseased plant incidence by taking the plot as a unit was calculated. Disease incidence was used to determine the response of each inbred to MRDV, which is 0 to 0.2% for high resistance, 2.1% to 5.0% for resistance, 5.1% to 10.0% for moderate resistance, 10.1% to 20.0% for susceptibility, 20.1% to 100% for high susceptibility, respectively. The disease evaluation resulted in identification of 12, 17 and 18 inbred lines offering high to moderate resistance to MRDV, besides 17 inbred lines conferring susceptibility. The diversity at the DNA level was investigated based on 70 SSR markers. The total number of alleles was 276. A mean polymorphism information content of 0.57, with a range of 0.177 to 0.825, was observed. The UPGMA analysis showed that 64 inbreds could be classified into six subgroups (Sipingtou, Luda Red Cob, PA, PB, BSSS and Lancaster), which were generally consistent to their known pedigree information and breeder’s experiences. Comprehensive differences were observed on the means of percent plants infected by MRDV among the six groups with the lowest level of 1.60% for PB and 4.95% for Sipingtou. Both groups were identified as the important sources of resistance to MRDV.

Identification of Wheat-Thinopyrum intermedium Telosomic Lines Resistant to Barley Yellow Dwarf Virus by GISH and STS Markers Converted from RFLP

CUI Zhi-Fu;LIN Zhi-Shan;XIN Zhi-Yong;TANG Yi-Miao;ZHANG Zeng-Yan;LU Qin

Acta Agron Sin. 2006, 32(12):  1855-1859. 

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Wheat yellow dwarf virus caused by barley yellow dwarf virus (BYDV) is one of the most serious diseases in wheat, and no resistant resource has been found in all wheat germplasms tested so far. According to our previous study, Wheat-Thinopyrum intermedium amphiploid Zhong 5 and its three derivatives, disomic addition lines Z1, Z2 and Z6, as well as three ditelosomic lines N523, N530 and N545 derived from Z6 showed high level resistance to BYDV and the resistance is associated with the alien chromosome of 2Ai-2. The objectives of this study were: i) to analyze the genetic composition of the telosome; ii) to screen and/or develop molecular markers co-segregated with the telosome; and therefore, iii) to determine the arm to which the telosome genetically belongs and consequently the location on which the BYDV resistance gene(s) and located. By using Pseudoroegneria.strigosa (St) genomic DNA as probe and Triticum astivum (ABD) genomic DNA as blocker, the results of GISH showed that two telosomes in line N530 were similar to the short arm but quite different from the long arm of 2Ai-2 chromosomes in Z6. Based on DNA sequences of five RFLP probes of chromosome homoeologous group2, six PCR primers were designed and used to develop molecular markers. One of the primers, STS₁₂₆, which was based on the sequence of psr126 from the short arm, showed that an about 730bp fragment was amplified specifically in BYDV resistant addition lines, substitution lines and ditelosomic lines but didn’t in wheat parents. It accordingly supported the GISH result that the telosome was the short arm of 2Ai-2 chromosome. In addition, the primer amplified three fragments in wheat parent which were determined by chromosome 2AS, 2BS and 2DS, respectively, according to the PCR patterns of different substitutions. The result of the tolesome being the short arm of 2Ai-2 chromosome was further confirmed by evidences from other two primers of STS₁₃₁ and STS₁₁₂. Primer STS₁₃₁ from short arm of group 2 amplified an alien chromosome-specific fragment which present in all alien addition lines and substitution lines including disomic and ditelosomic lines, while primer STS₁₁₂ from long arm of group 2 amplified an alien chromosome-specific fragment only in alien disomic addition and substitution lines, but neither in alien ditelosomic lines nor in wheat parents. This study not only localized the resistant gene on the short arm of 2Ai-2 chromosomes, but also successfully converted three RFLP probes into STS markers, named as STS₁₂₆, STS₁₃₁ and STS₁₁₂. They could be used to track the different arms of 2Ai-2 chromosome and would facilitate the screening for the translocation lines with BYDV resistance effectively.

Effects of Nitrogen Rate and Ratio of Base Fertilizer and Topdressing on Uptake, Translocation of Nitrogen and Yield in Wheat

SHI Yu;YU Zhen-Wen;WANG Dong;LI Yan-Qi;WANG Xue

Acta Agron Sin. 2006, 32(12):  1860-1866. 

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Application of nitrogen (N) fertilizer is one of the most important measures to increase grain yield and protein content in winter wheat (Triticum aestivum L.) production. However, misuse of N fertilizer will not only affect grain yield and quality, but also cause the decline of economic effects and related environmental effects. It is essential to study reasonable nitrogen applying regimes for profitable yields, efficient N utilization, and reduction of possible environment pollution. The objectives of this study were to determine the N uptake and translocation in wheat plant by using 15N isotope tracer in PVC cylinders (2.05 m length, Ф0.2 m, without bottom) with seven treatments: without applying N fertilizer (N0); N application rate of 168 kg N&#903;ha^-1 (0.527 g/pot), ratios of base fertilizer to topdressing of 1:1 (N1), 1:2 (N2) and 0:1(N3); N application rate of 240 kg N&#903;ha^-1 (0.753 g/pot), ratios of base fertilizer to topdressing of 1:1(N4), 1:2(N5) and 0:1(N6). Treatment N4 is a regime applied now in local wheat production. At the same time, the field experiment was conducted in the same field, and experimental design is same as that of the 15N isotope tracer experiment with three repetitions. The plot area was 3 m×8 m=24 m². At the three-leaf stages, the seedlings were thinned to a density of 150 plants per m².
¹⁵N tracer experiment showed that main basal nitrogen absorbed by plant from sowing to jointing stage accounted for 78.04%–89.67%; fertilizer-N use efficiency (N fertilizer accumulation in plant/N supplied, FNUE) of topdressing was markedly higher than that of basal nitrogen; reducing basal nitrogen amount and increasing topdressing nitrogen amount could appropriately promote plant to absorb more fertilizer nitrogen, and enhance FNUE, of which treatment N2 was the highest. In high-yield condition this study concerned, when nitrogen (N) fertilizer rate increased from 168 kg·ha^-1 to 240 kg·ha^-1, the amount of N accumulation in plant and in grain had no significant difference between treatments with the same ratio of base fertilizer to topdressing; with reducing basal nitrogen amount and increasing topdressing nitrogen amount appropriately, the translocation efficiency (accumulation amount from vegetative organs to grain/N accumulation in vegetative organs on anthesis, TE) heightened, and the amount of nitrogen assimilation for grain after anthesis and its contribution proportion (the amount of nitrogen assimilation to grain after anthesis/N accumulation in grain) also increased, in other words grain N accumulation amount increased with increasing amount of topdressing nitrogen in the same nitrogen fertilizer rate. There was no significant difference among treatments N2, N3, N5 and N6 in grain nitrogen accumulation. Appropriate N fertilizer rate with reducing basal nitrogen amount and increasing topdressing nitrogen amount such as in N2, N5 and N6 increased grain yield and protein content. In conclusion, under the condition of this experiment, as far as grain yield, protein content and fertilizer-N use efficiency are concerned, the most appropriate nitrogen fertilizer applying regime recommended is treatment N2, its nitrogen fertilizer rate is 168 kg·ha^-1 and ratio of base fertilizer to topdressing is 1:2.

Microsatellite Markers for A Yellow Rust Resistant Gene in Wheat Cultivar Guinong 21

CHENG Ying;SONG Wei;LIU Zhi-Yong;XIE Chao-Jie;NI Zhong-Fu;PENG Hui-Ru;NIE Xiu-Ling;YANG Zuo-Min;SUN Qi-Xin

Acta Agron Sin. 2006, 32(12):  1867-1872. 

Abstract ( 1985 )   PDF (1077KB) ( 1244 )   Save

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Yellow rust, caused by Puccinia striiformis Westend f. sp. tritici, is one of the most important diseases of wheat (Triticum aestivum L.) worldwide. Breeding for resistance is considered the most economical and effective mean for controlling the disease. Guinong 21, a common wheat cultivar derived from an open pollinated population between common wheat and the F₁ hybrid of Haynaldia villosa and Triticum durum, provided sound resistance to prevalent Chinese races of Puccinia striiformis f. sp. tritici and Blumeria graminis f. sp. tritici for decades. Genetic analysis indicated that Guinong 21 is carrying a single dominant yellow rust resistance gene, designated as YrGn21 temporarily. Segregating F₂ progenies of the cross (Guinong21/704) F₂/Wenmai8 were used for bulked segregation analysis (BSA). Eleven microsatellite markers, Xcau14, Xwmc49, Xgwm403, Xgdm62, Xwmc272, Xgwm459, Xbarc240, Xbarc187, Xgdm28, Xgwm11 and Xgwm413 were found to be linked to YrGn21 and all of them were assigned to the same side of gene YrGn21. The closest marker Xcau14 was mapped 1.1 cM away from the resistant gene and the furthest marker Xgwm413 was located 7.1 cM to YrGn21. Based on the reported genetic and physical maps of microsatellites in wheat, most of these YrGn21 linked markers have been mapped in the adjacent region of centromere on chromosome 1BS. It had been reported that Xgwm11 and Xgwm413 were linked to yellow rust resistance gene Yr26, which was also located on chromosome 1BS. Polymorphisms detected by the 11 YrGn21 linked markers on an Yr26 population indicated that same polymorphic fragments could be amplified by 10 out 11 primers on the resistant plants of YrGn21 and Yr26. It is deduced that YrGn21 might be an allelic locus of Yr26 and the 11 close linked markers to the resistant gene (YrGn21) established in this research would facilitate the marker-assisted selection (MAS) and the pyramiding of YrGn21 in wheat breeding programs.

Analysis of Embryo, Cytoplasmic and Maternal Effects on Fatty Acid Components in Soybean（G. max Merill）

NING Hai-Long;LI Wen-Xia;LI Wen-Bin

Acta Agron Sin. 2006, 32(12):  1873-1877. 

Abstract ( 1908 )   PDF (449KB) ( 1014 )   Save

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Quality of oil determined by the constituents and proportion of fatty acid components, and the understanding of heredity of fatty acid components is of importance to breeding for good quality soybean varieties. Embryo, cytoplasmic and maternal effects and genotype×environment interaction effects for quality traits of soybean （G. max Merill）seeds were analyzed using a general genetic model for quantitative traits of seeds with parents，F₁ and F₂ of 20 crosses from a diallel mating design of 5 parents planted in the field in 2003 and 2004 in Harbin, China. The interaction effects of palmitic, stearic and linoleic acids contents were larger than genetic main effects，while genetic main effects were equal to interaction effects for linolenic and oleic acids content. Among all kinds of genetic main effects，the embryo effects were the largest for palmitic，stearic and linoleic acids，and cytoplasm effects were the largest for oleic and linolenic acids. Among all kinds of interaction effects，the embryo interaction effects were the largest for fatty acids. The sum of additive and additive×environment effects were larger than that of dominance and dominance×environment effects for linolenic acids content, but not for other quality traits. The general heritabilities were the main parts of heritabilities for palmitic acids content and oleic acids content，but the interaction were more important for stearic, linoleic and linolenic acids contents. For the general heritability, maternal and cytoplasm heritabilities were the main components for palmitic, oleic and linolenic acids contenst. It was shown for the interaction heritabilities that embryo interaction heritabilities were more important for oleic and linolenic acids contents，while maternal interaction heritabilities were more important for linoleic acids content. Among selection response components，maternal and cytoplasm general responses and/or interaction responses were more important for palmitic, stearic, oleic and linoleic acids contents. The main selection response components were from embryo general response and/or interaction response for linolenic acid content. It suggested that the selection of palmitic, stearic, oleic and linoleic acids contents in offspring should be in maternal plants，while linolenic acids content should be improved screening the single seed or selected in higher generations.

A Preliminary Study on Yield and Quality of Rice and Their Relationship with Panicle Characters in Northeast Region

XU Zheng-Jin;SHAO Guo-Jun;HAN Yong;ZHANG Xue-Jun;QUAN Cheng-Zhe;PAN Guo-Jun;CHEN Wen-Fu

Acta Agron Sin. 2006, 32(12):  1878-1883. 

Abstract ( 2159 )   PDF (463KB) ( 1174 )   Save

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Forty-six rice cultivars and lines attended regional trials in Liaoning, Jilin and Heilongjiang provinces in 2004 were used to study panicle characteristics and it relationship with yield and quality in Shenyang city, Gongzhuling city and Jiamusi city with higher cultivated level. The results indicated that there was significant difference in grain yield and yield components between different cultivars and lines, and grain yield of Liaoning province was significantly higher than that of Jilin and Heilongjiang provinces, but there was no significant grain yield difference between Jilin and Heilongjiang. The number of panicle per unit area and grains per panicle in Liaoning were very significantly lower than those in Jilin and Heilongjiang, and other yield components were not significantly different among different provinces. Difference of panicle traits was significantly different among all the materials in these provinces, except seed-setting rate of primary branch. The panicle length of Liaoning was 2 cm shorter than that of Jilin and Heilongjiang, and grains density, the number of primary branch and primary branch grains in Liaoning were very significantly larger than those in Jilin and Heilongjiang. Brown rice percentage was in order of Jilin＞Liaoning＞Heilongjiang, milled rice percentage was in order of Jilin＞Liaoning and Heilongjiang, head rice percentage was in order of Heilongjiang ＞Jilin＞Liaoning, the ratio of grain length to width in Liaoning and Heilongjiang was higher than that in Jilin. Chalky grain rate in Jilin was higher than that in Liaoning and Heilongjiang, the taste value was the highest in Heilongjiang, and followed by in Jilin and Liaoning. The processing quality was negatively correlated to grains per panicle, grain density, primary branches, the number of primary branch, secondary branches, ratio of secondary branch grains/total grains, but positively correlated with seed setting rate, seed-setting rate of primary branch and secondary branch, and the relationship between eating quality and panicle character appeared the similar trend.

Breeding of Male Sterile Restorer Lines Matching with cms-FA Lines of New Male Sterile Cytoplasm Genes from Oryza rufipogon

WANG Nai-Yuan

Acta Agron Sin. 2006, 32(12):  1884-1891. 

Abstract ( 1902 )   PDF (579KB) ( 1373 )   Save

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It is an important approach to discover new resources of male sterile cytoplasm and to develop good quality CMS lines so as to reduce hybrid rice chalkiness, lower amylose content and substantially increase hybrid rice quality. A new male sterile cytoplasm named FA cytoplasm, which is different from WA and HL in the relationship between the maintainer line and the correspondent restorer line, has been obtained through nuclear substitution of Common Wild Rice（O. rufipogon）with the nuclear of cultivated rice by backcrosses. And the relevant CMS lines with fine rice quality, Jinnong 1A and Jinnong 2A were developed, which laid a good foundation for substantially improving the quality of hybrid rice. The subsequent breeding of the restorer line is therefore a key matching technique for the application of FA male sterile lines. In this study, the directional breeding method for male sterile restorer lines matching with FA cytoplasm was designed.
Hybridization and backcrosses were conducted by using the wild rice as non-recurrent parent and Minghui 63 as recurrent parent. The fertile genes from the wild rice were segregated, transfered, recombined and integrated into the genetic background of Minghui 63 by self-crosses of descendants to obtain a new male sterile restorer line Jinhui 1 with new male sterile cytoplasm.
The restorer line resembled Minghui 63 in agro-chaits with its spikelets completely fertile. Two hybrid rice combinations of Jinnong 1A/ Jinhui 1 and Jinnong 2A/Jinhui 1 were superior in yield compared with CK combination. All the twelve rice quality indexes approached those of fine quality rice, and the goal of greatly improving hybrid rice quality was realized.
Backcrosses could be used to input genes of recurrent parents time after time, expand genetic proportion of recurrent parents generation after generation, reduce the proportion of non-target genes from non-recurrent parents generation after generation and enlarge the genetic distance between a restorer line and a sterile line to reach the aim of improving heterosis. By using this method, fertile genes can be transferred so that any rice variety can be lead to be a male sterile restorer line, which breaks the technical bottle-neck in breeding restorer lines matching with sterile lines of the new sterile cytoplasm, greatly increases the breeding potential in the searching of restorer lines and therefore cuts a new way for the development of FA male sterile lines and fine quality hybrid rice.

Effects of Water Stress on Some Physiological Characteristics in Rice during Grain Filling Stage

WANG He-Zheng;MA Jun;LI Xu-Yi;LI Yan;ZHANG Rong-Ping;WANG Ren-Quan

Acta Agron Sin. 2006, 32(12):  1892-1897. 

Abstract ( 1941 )   PDF (444KB) ( 1132 )   Save

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Along with the increasing scarcity of global water resource, water shortage is crucial for restricting agricultural development in china. Rice is one of the main staple food crops in the world, and may suffer serious water stress during its growth period. Water stress during grain filling results in decreasing grain yield, and its physiological mechanism is unclear under continuance of the water stress. So study on the relationship between water stress and drought resistance in rice have become increasingly important proposals of rice scientific researches. The experiments were carried out in growth chamber to investigate the effects of water stress on MDA，photosynthetic rate, stomatal conductance, osmotic regulators and antioxidative enzyme activities in three hybrid rice cultivars (combinations) with different drought resistant abilities under both normal and drought conditions during grain filling stage. The results indicated that water stress aggravated the membrane lipid peroxidation in rice leaves, and it was more severe in weaker drought resistant cultivars than in better drought resistant cultivars. During the period of water stress, decreases of photosynthetic rate, stomatal conductance and chlorophyll content in better drought resistant cultivars were obvious less than those in weaker drought resistant ones. Contents of soluble sugar and amino acid and activities of superoxide dismutase(SOD), catalase(CAT) and peroxidase(POD) in leaves increased obviously in 0–14 d after anthesis and subsequently decreased rapidly, and the increases were more in better drought resistant cultivars than in weaker drought resistant ones in 0–14 d after anthesis. These results suggest that water stress can induce physiological and biochemical changes in rice, and the changes indicate drought resistance of rice during grain filling stage. Changes of MDA content, photosynthesis, osmotic regulators and antioxidative enzyme activities are correlated significantly to drought resistance of rice varieties.

Molecular Cytogenetics Identifications on Triticum aestivum-Elymus rectisetus Alien Addition Lines

WANG Chang-You;JI Wan-Quan;ZHANG Gai-Sheng;WANG Qiu-Ying;XUE Xiu-Zhuang

Acta Agron Sin. 2006, 32(12):  1898-1901. 

Abstract ( 2011 )   PDF (1242KB) ( 1002 )   Save

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The alien addition lines of T. aestivum can be used to breed the alien substitution lines and the alien translocation lines, to locate the alien genes on the specific chromosome, and to construct the alien chromosome DNA library. Elymus rectisetus (Nees in Lehm) A. Löve et Connor is the only species known with apomixes in the tribe of Triticeae. Three 2n=44 lines 1026A1, 1057A1 and 1035A2 were derived from [E. rectisetus × Fukuhokomugi (T. aestivum)] BC₂F₂ progeny. Cytogenetic, genomic in situ hybridization (GISH) and RAPD were applied to identify and tag E. rectisetus chromosomes of three lines. Chromosome configurations at PMC MⅠ of three lines were 2n=22Ⅱ. Chromosome configurations of hybrid F₁ between three lines and Fukuhokomugi were 2n=21Ⅱ+1Ⅰ. Chromosome configuration of half diallel cross F₁ between three lines were 2n=21Ⅱ+2Ⅰ. The probe was total genomic DNA of E. rectisetus accession 1050 labbelled with BioNick&#8482; Labeling System and the block DNA was total genomic DNA of Fukuhokomugi. GISH analysis demonstrated that two E. rectisetus chromosome of three lines were detected, respectively. Genomic DNAs was isolated from E. rectisetus accession 1050, Fukuhokomugi and three lines, and was used for PCR amplification with 13 RAPD primers (OPB-08, OPB-14, OPE-09, OPF-05, OPF-09, OPJ-05, OPK-03, OPN-12, OPP-20, OPS-12, OPT-20, OPZ-09 and OPZ-11). OPB-14 and OPE-09 could amplify the E. rectisetus specific DNA bands OPB-14900bp and OPE-09750bp in 1026A1. OPB-14 could amplify the E. rectisetus specific DNA bands OPB-141000bp in 1057A1. The results of cytogenetic and GISH analysis showed that 1026A1, 1057A1 and 1035A2 lines were T. aestivum-E. rectisetus alien disomic addition lines with different E. rectisetus chromosomes. The results of RAPD amplification showed that OPB-14900bp, OPE-09750bp and OPB-141000bp could be used as molecular markers to detect E. rectisetus chromation in alien disomic addition lines 1026A1 and 1057A1, respectively.

Analysis of RVA Profile Diversity in Local Late Japonica Rice at Taihu Lake Area

SHEN Xin-Ping;SHEN Ming-Xing;GONG Li-Ping;JI Hong-Juan;YAO Yue-Ming;WANG Jian-Ping

Acta Agron Sin. 2006, 32(12):  1902-1908. 

Abstract ( 2347 )   PDF (514KB) ( 981 )   Save

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The RVA profile is one of the key characters in evaluating the pasting property of the rice starch, and has been a primary index for improving the taste quality the rice. While the assessment of the local rice resource has always been the important part of the genetic improvement of crop, the research on the diversity of the RVA profile among the local rice resources can offer a basis for the further utilization of the local resources. In this paper, 368 late japonica rice cultivars in Taihu Lake area collected around 1950s were employed to performe the RVA profiles. The results showed that the rice starch RVA profile was different among tested cultivars. And the RVA parameters of different materials were also found significantly different from each other, exhibiting continuous variation from indica type to glutinous type, which consequently formed four groups. The setback viscosity value of a large portion of the local germplasm (about 51.9% in all samples) ranged from 300 to 1 000 cP. This portion of the materials thus fallen into typical japonica cultivar, and the corresponding RVA profile belonged to the category A. A few germplasm (such as Dahongdao, Zaorihuangdao, Shanghaiqing, Suzhouqing, Manghonggu) had characteristic RVA profile same as that of glutinous cultivars, the corresponding RVA profile was the category C. While some RVA profiles of other germplasm (such as Jinguhuang, Manbaidao, Cuyingyangwandao, Xidiegu, Ligengqing) were similar to that of typical indica cultivar, and corresponded to the category D. In the sampled cultivars, some of which (such as Tianxiadiyizhong, Daqingzhong, Huanggudadaotou, Yaoaizi, Yushanzhong) had RVA profile of cultivars with good quality, namely, the setback value was negative. The RVA profiles of Taihu lake area local cultivars indicated there were significant diversities in rice starch quality. Further, the generalized heritability diversity index of every characteristic value was calculated and all of indices were more than 1, among them that of breakdown reached to 2.06. Correlation analysis showed that characteristic values of RVA profile were correlated with each other, and the rice RVA profile characteristics could be described quantitatively by breakdown and setback.

RESEARCH NOTES

Cytolgical Observation and Analyses of A₃ Cytoplasmic Male Sterility in Sorghum

YI Zhi-Ben;LIANG Xiao-Hong;ZHAO Wei-Jun;CUI Gui-Mei;SUN Yi;CUI Li-Xia

Acta Agron Sin. 2006, 32(12):  1909-1912. 

Abstract ( 1878 )   PDF (559KB) ( 971 )   Save

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A₃ male sterile cytoplasm in sorghum (Sorghum bicolor L. Moench) is from IS1112C. Among the seven kinds of cytoplasmic male sterility (CMS) in sorghum, the sterility in A₃ CMS is most stable, and very difficult to restore. In this study A₃ male sterile line Jingliang 5 and corresponding maintainer B₃ Jinliang 5 were used to study the process of A₃ CMS anther development and analyze the chromosomal behaviors of meiosis during microspore formation, in order to understand the basis of A₃ CMS genesis. The results showed that differing from that in A₁ and A₂ CMS, the meiosis of pollen mother cell (PMC) in A₃ Jinliang 5 was completed normally. No abnormal meiotic behaviors were observed compared to its corresponding maintainer B₃ Jinliang 5. In sporogenous cell stage, premeiotic interphase and meiosis stage, no abnormal phenomena were found. Tetrad separated normally in paraffin-embedded A₃ male sterile line anther section observation. But in pollen mature stage deformed pollens were observed and it was in this stage, i.e. about 7 days before anthesis, the normal development of microspores was affected, sucrose-starch metabolic pathway was blocked and no starch particles were deposited on intine of A₃ CMS pollens, leading to unviable pollen formation.

Characteristics of Photosynthesis and Photo-oxidation in the Hybrid between Oryza sativa and Oryza rufipogon

LI Tao;DING Zai-Song;GUAN Dong-Ming;CHEN Chuan-Yong;SUN Rui;ZHAO Ming

Acta Agron Sin. 2006, 32(12):  1913-1916. 

Abstract ( 1916 )   PDF (171KB) ( 966 )   Save

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During the grain-filling period, photosynthesis in rice plants contributes 60%–100% of the final grain carbohydrate, but in the mean time, photo-oxidation caused by low temperature and high light is always suffered by top leaves. So it is same importance to increase the resisting photo-oxidation, as well as to improve net photosynthetic rate (P_n) in this period. In previous works, the progenies (SHPF₆) which had high net photosynthetic rate were obtained from the hybrids Oryza sativa Azucena × Oryza rufipogon Ramper 6. Photosynthetic structures of them have been transformed so that a high G_s can be seen. But it is not known whether these progenies also have a high net photosynthetic rate in the grain-filling period and whether they can resist the photo-oxidation under the high light circumstance after the MV treatment. Thus, in this paper, a MV treatment was applied, photosynthetic parameters and chlorophyll fluorescence were measured to identify the extent of photo-oxidation. The results showed that SHPF₆ had a high P_n under high light in the filling-grain period and the Pn increased with the further increment of light intensity. There was a significant correlation with between and P_n C_i (r = －0.767, P<0.01). After MV treatment, the value of F₀, F_v/F_m and F_v/F₀ changed significantly in Zhonghua 10 (P < 0.05), but not in SHPF₆. All of this results suggested that the method of distant crossing can not only improve the net photosynthetic rate, increase stomatal conductance and promote the efficiency of CO₂ assimilation in the filling-grain period, but also increase the resistance to photo-oxidation.

Characteristics of Pre-Harvest Sprouting in Wheat with Different Types of Wx Protein Absence

GAO De-Rong;GUO Wen-Shan;CHENG Shun-He;FENG Chao-Nian;ZHU Xin-Kai;PENG Yong-Xin

Acta Agron Sin. 2006, 32(12):  1917-1919. 

Abstract ( 2072 )   PDF (230KB) ( 945 )   Save

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In order to investigate the pre-harvest sprouting(PHS) percentage, α-amylase activity and soluble sugar content in grains of 11 varieties with complete Wx proteins absence(waxy type), 11 varieties with one or two Wx proteins absence(non-waxy type), 2 varieties with complete Wx proteins(non-waxy type) and 1 white grain cultivar as a PHS check in wheat (Triticum aestivum L.). The results showed that the PHS percentage and soluble sugar content in grains of waxy wheat varieties were significantly higher than those of non-waxy type, but there was no significant difference in α-amylase activity between two types. The activity of α-amylase(x) significantly affected PHS percentage (y) in non-waxy wheat varieties, y=0.4145 e^0.4864x(R²=0.3513*), and soluble sugar content(x) in grains was significantly related to pre-harvest sprouting percentage for waxy wheat, y=0.0001 e^2.5599x(R²=0.5338**).High soluble sugar content might be an induced factor of PHS in waxy wheat.

High Molecular Weight DNA Preparation from Nuclei or Chromosomes of Root Meristem of Wheat

GUO Dong-Wei;SHE Mao-Yun;LI Lian-Cheng;CHEN Yao-Feng;CHEN Ming;XU Zhao-Shi;MA You-Zhi

Acta Agron Sin. 2006, 32(12):  1920-1923. 

Abstract ( 2061 )   PDF (842KB) ( 947 )   Save

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A simple and practical method was optimized to overcome the limitations of current method by which HMW DNA was prepared from leaf powder. Root tips of synchronized meristem were homogenized to make preparing suspension containing intact metaphase chromosomes and nuclei, which were further isolated by sucrose gradient centrifugation and flow sorting, respectively. Finally, HMW DNA was prepared with deproteinization, digestion and dialysis of nuclei and chromosomes. The results showed that concentration of the HMW DNA from 200 root tips (10 plugs) was about 4–20 ng/µL (4 ng/µL in chromosomes DNA and 20 ng/µL in nuclei DNA). The average insert fragment size was more than 100 kb after linage, transformation and insert fragment examination by pulse field gel electrophoresis for HMW DNA from nuclei. The similar results were obtained by HMW DNA prepared from chromosomes. It is confirmed that the method is applicable to prepare HMW DNA for construction of BAC library.

The Sub-cellular Localization of the Bt Crystal Protein in Transgenic Bt Cotton Cell

DONG Zhi-Qiang;ZHAO Ming;SHU Wen-Hua;ZHANG Bao-Ming;HAO Hong-Jing

Acta Agron Sin. 2006, 32(12):  1924-1926. 

Abstract ( 1714 )   PDF (1007KB) ( 981 )   Save

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For the sake of proving the localization character of Bt crystal protein in transgenic Bt cotton cell and illustrating the insect resistance stability of Bt cotton, the study on the sub-cellular orientation of the Bt crystal protein in transgenic Bt cotton cell was conducted by means of immunocyte localization. The results showed that the Bt crystal protein were mostly located in cytoplasm and the intercellular space of Bt transgenic cotton GK-12 cotyledon mesophyll cells. The distribution density was larger in cytoplasm than in the intercellular space. In cytoplasm, the crystal protein was mainly distributed on the cell membrane, endoplasmic reticulum, chloroplast and plastid, especially on the surface of chloroplast and plastid with a high density. From above, we know that the Bt. crystal protein is straightly located onto inertial organelle—chloroplast and its plastid.