Wan Jianmin

Screening of rice resources against rice black-streaked dwarf virus and mapping of resistant QTL.

Rice black-streaked dwarf virus(RBSDV)disease become epidemic in Jiangsu and Zhejiang provinces. To screen resis- tant germplasms and discover new resistance genes/QTLs against RBSDV, we evaluated the resistance to RBSDV in 311 japonica cultivars in field test. The results showed that no cultivar was immune to RBSDV. The disease rate of 24 main japonica cultivars grown in Jiangsu province at present was 10.0%-29.0% and that of 71.5% cultivars in 287 japonica cultivars popularized in Ji- angsu before was between 10.0% and 30.0%. Furthermore, quantitative trait loci (QTL) analysis was conducted by using 162 recombinant inbred lines (RILs), which derived from a cross between Guichao 2, a susceptible indica variety, and Koshihikari, a japonica variety with resistance to RBSDV. RBSDV resistances were evaluated using natural infection methods by scoring the disease rating. One putative QTL (qRBSDV3) controlling RBSDV resistance was mapped between the marker RM7 and RM5748 on chromosome 3, which explained 17.1% of the total phenotypic variation with LOD score of 5.4. The positive resistant effect contributed from Koshihikari. Further analysis revealed that the lines harboring the alleles of qRBSDV3 exhibited significantly increased resistance to RBSDV. The results should be very useful for breeding new RBSDV-resistant cultivars by marker-assisted

QTL Mapping and Interaction Analysis for 1000-Grain Weight and Percentage of Grains with Chalkiness in Rice

There is a close correlation between 1000-grian weight(TGW,an important yield factor) and percentage of grains with chalkiness(PGWC,an important rice quality index).In this study,a backcross inbred lines(BIL) population derived from a cross between Koshihikari(japonica) and Kasalath(indica) was used to detect correlations and among interactions QTL,epistatic and environment on TGW and PGWC.Correlation analysis showed that there was a significantly positive correlation between TGW and PGWC in the BIL population and the correlation coefficients were 0.42 and 0.35(P0.001) in 2005 and 2006,respectively.A total of eleven QTLs and eight epistatic interactions for TGW were detected in 2005 and 2006;of them,five QTLs were repeat-edly detected in the two years,and five QTLs and seven epistatic interactions had significantly QE interaction.A total of six QTLs and nine epistatic interactions for PGWC were detected in 2005 and 2006;of them,three QTLs and four epistatic interactions had markedly QE interaction.Three main-effect QTLs simultaneously controlling TGW and PGWC were detected,and their alleles increasing TGW and PGWC were from the same parent;one epistatic interaction had similar effects on TGW and PGWC.Some main-effect QTLs,controlling TGW but not PGWC,such as qTGW-3c,qTGW-4a,and qTGW-6b,could be used for breeding.The strategy was discussed in using QTL mapping results for the marker-assisted selection breeding of TGW and PGWC.

Precision evaluation of rice variety regional trials in northern China.

Crop variety regional trial is the basis of variety registration.The precision of regional trial directly influences the merits of approved varieties.According to new national certification standards,new rice varieties should yield more than 3% compared with the control,requiring much higher precision of the experiments.Since 1999,the national rice regional trials in northern China have been implemented for 10 years.It is extremely important for the variety approval committee to known that whether or not the experiments precision can reach the national registration requirements.Based on the data from rice variety regional trials in northern China from 1999 to 2008,we analyzed the experiment error precision(EP) and variety comparison precision(VCP) at two experiment levels.The results was as follows:(1) The average coefficient of variation(CV) and relative LSD(RLSD) in one-location-one-year experiments were 4.3% and 7.4% respectively,indicating the trials were well controlled.Both EP and VCP in one-location-one-year experiments were desirable.(2) The average CV and RLSD in most of multi-location-one-year experiments were lower than 5% and 3% respectively.The EP and VCP in multi-location-one-year experiments were desirable and met the requirements of the State Variety Approval.(3) Under the existing design of experiments,reducing experimental errors in the trials is the main way to improve the accuracy of one-location-one-year experiment.In addition to reducing experimental errors in the trials,the appropriate increase in the number of experiment sites is also a very effective choice to improve the accuracy of multi-location-one-year experiments.

水稻胚乳粉质突变体 flo9 的表型分析和基因定位

目的淀粉是水稻的主要成分，其含量、组成和结构对稻米品质至关重要，因此，对淀粉合成及调控路径的进一步解析将有助于稻米品质的改良。 方法从60Co辐射诱变的‘N22’突变体库中筛选获得一份粉质、皱缩、纯合致死的突变体flo9，分析了其形态学特征和理化性质，利用扫描电镜和半薄切片技术观察胚乳内部结构；配制flo9和‘滇粳优1号’的F2群体，并挑选粉质极端个体进行定位；利用qRT-PCR分析淀粉合成相关基因的表达模式。 结果与野生型相比，flo9突变体的千粒质量、粒长、粒宽、粒厚、直链淀粉含量和脂肪含量均显著降低，而总淀粉含量无显著差异。突变体中淀粉消减值、回复值和崩解值以及米粉在尿素溶液中的溶解能力低于野生型。突变体中造粉体多为圆形或椭圆形，单粒淀粉颗粒增多，造粉体之间排列疏松。利用314个粉质极端个体将FLO9定位在第9染色体长臂123 kb的区间内，该区间包含13个开放阅读框（ORFs）。qRT-PCR分析发现多个淀粉合成和脂质合成相关基因出现不同程度的表达变化。 结论FLO9参与调控胚乳中淀粉和脂质的合成以及造粉体的发育，为FLO9的克隆和功能解析奠定了基础。

水稻矮秆突变体 htr 的表型分析及基因克隆

目的对水稻矮秆突变体htr进行表型分析与基因克隆，为水稻育种提供新的矮秆基因资源。 方法对矮秆突变体htr茎秆进行细胞学观察，并将htr与‘N22’和‘9311’杂交构建F2群体，提取隐性极端个体定位基因HTR。 结果htr是一个稳定遗传的矮秆突变体，其株高、穗长、千粒质量、分蘖数等性状均降低，但其叶片变宽，叶色深绿，茎秆增粗。成熟期对htr倒二节间进行切片观察发现：相比‘9311’，htr在茎秆的纵轴方向细胞未能正常伸长，横向细胞数目增多，细胞变小。遗传分析表明突变体htr的矮秆性状受1对隐性单基因控制。利用F2群体中隐性极端个体将HTR定位在第5染色体长臂ttr-1和ttr-2两个分子标记之间，物理距离大约在144 kb范围内。测序结果发现htr中编码AP2转录因子（AP2-like ethylene-responsive transcription factor）基因发生点突变，导致保守氨基酸发生替换，亚细胞定位显示HTR定位于细胞核中。HTR呈现组成型表达，但以在茎秆中表达量最高。 结论矮秆突变体htr突变性状受一对编码AP2转录因子的隐性单基因控制。HTR基因的克隆对培育厚壁粗秆抗倒伏水稻新品种提供了一定的理论参考。

Initial function determination for the open reading frame (ORF) region of Pib gene via rice transformation

Three plant binary expression vectors—pNAR501, pNAR502 and pNAR503—were constructed, carrying fragments of exon2-exon3, 5′partial deletion exon1 and 5′partial deletion exon1-exon2-exon3 of Pib gene driven by 35S. These three vectors were transformed into the japonica rice variety Nipponbare through agrobacterium-mediated transformation. More than 30 transgenic rice plants were obtained and confirmed by polymerase chain reaction (PCR), Southern hybridization and the hygromycin resistance test in seed germination of their progeny. A rice blast resistance test for in vitro leaves of To transgenic plants in the tillering stage showed higher resistance to the races of E1, F1 and G1 of rice blast than that of the control Nipponbare. However, results of rice blast resistance test for seedlings of T1 transgenic plants in the 3-to 4-leaf stage were different. All T1 transgenic seedlings had a lower level of resistance to E1, F1 and G1 races than that of the control Nipponbare.