A draft sequence of the rice genome (Oryza sativa L. ssp. indica)

We have produced a draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp. indica, by whole-genome shotgun sequencing. The genome was 466 megabases in size, with an estimated 46,022 to 55,615 genes. Functional coverage in the assembled sequences was 92.0%. About 42.2% of the genome was in exact 20-nucleotide oligomer repeats, and most of the transposons were in the intergenic regions between genes. Although 80.6% of predicted Arabidopsis thaliana genes had a homolog in rice, only 49.4% of predicted rice genes had a homolog in A. thaliana. The large proportion of rice genes with no recognizable homologs is due to a gradient in the GC content of rice coding sequences.     

粳稻粒重与稻米外观品质的相关性

对外观品质优质的小粒粳稻品系与大粒大垩白粳稻品系的杂交F2及BC1F1代植株谷粒性状与外观品质性状的关系进行了分析。结果表明,粒重与垩白呈显著正相关,粒宽对外观品质的影响最大;杂种后代出现了外观品质达到优质小粒亲本水平,且干粒重比优质小粒亲本高5．4g的单株;干粒重超过32．0g的单株,外观品质均未达到国家3级优质稻谷标准;用优质亲本回交,有利于提高杂种后代优质单株的出现机率。     

水稻胚乳特异型双向启动子的克隆及功能鉴定

以水稻中的1对双向转录基因(TIGR Locus:LOC_Os09g39540和LOC_Os09g39550)的翻译起始位点之间的序列作为研究对象,克隆其序列并进行功能鉴定。以明恢63基因组DNA为模板,采用PCR法扩增该序列(命名为BDP1),以正反两个方向插入启动子功能分析载体pDX2181,分别命名为BDP11和BDP12;转基因阳性植株的GUS组织化学染色结果证明该启动子为胚乳特异型的双向启动子,两端的表达水平均很低。将启动子片段距离转录起始位点较短的一端向下游延伸123bp(命名为BDP2),以正反两个方向插入启动子功能分析载体pDX2181,分别命名为BDP21和BDP22;转基因阳性植株的GUS组织化学染色结果显示该启动子的胚乳特异型双向表达模式维持不变,表达水平高于BDP1。     

粳稻MYB蛋白家族的生物信息学分析

运用隐马尔柯夫模型(Hidden Markov model,HMM),对粳稻Oryza sativa L. ssp. japonica的蛋白质数据库进行搜索,共找到192个MYB蛋白同源序列,其中有126个R2R3-MYB蛋白,6个R1R2R3-MYB蛋白以及60个MYB相关蛋白(MYB-related protein).进一步分析所有粳稻的MYB蛋白基因在染色体上的分布,结果发现,MYB基因基本上是成簇分布的,在染色体1～8号特别明显.运用基于EM(Expectation maximization)算法的MEME程序,对MYB蛋白的功能域进行多序列比对分析,确定了R1、R2与R3结构域在每个位置上最大可能氨基酸的频率.此外,还对水稻中的MYB蛋白家族作了初步的进化分析.     

粳稻粒形对稻米垩白性状的影响

将粳稻小粒优质品系与大粒大垩白品系杂交，考察F2及BC1F1的粒形性状与垩白性状，研究粒形对垩白性状的影响。结果表明，粒重增加主要是以粒长增长为主；粒形性状与垩白性状均呈显著正相关，粒宽与垩白性状的相关系数最大；优质植株中长／宽在2．01～2．30的株数占优质总数的85．37％，适当地提高长／宽，对选择大粒优质个体是有利的。     

粳稻籽粒性状遗传分析

[目的]对籽粒相关性状进行遗传分析,为水稻高产改良提供指导。[方法]以秀水79和C堡构建的247个株系粳粳交重组自交系群体为试验材料,测定了籽粒相关性状(粒长、粒宽、粒重及长宽比)的表型值,利用主基因+多基因混合遗传模型对其进行遗传分析。[结果]粳稻粒长和粒重都受到3对主基因控制,二者均无多基因控制。粒宽为2对主基因控制无多基因的作用方式,粒长、粒宽和粒重主基因的遗传率均在99%以上。籽粒长宽比由多基因控制。[结论]粳稻粒长、粒重和粒宽受到主基因控制。     

Experimental and genomic evidence for the indica-type cytoplasmic effect in Oryza sativa L.ssp.japonica

Cytoplasmic effects are important agronomical phenomena that have generated widespread interest in both theory and application. In the present study, five high yield rice cultivars(Oryza sativa L. ssp. japonica) in large-scale cultivation in northeast China were determined to possess Oryza sativa L. ssp. indica-type cytoplasm using cytoplasmic subspecies-specific molecular markers. This was confirmed by cytoplasmic genome-wide single nucleotide polymorphisms(SNPs) and functional gene sequencing. Two of these five japonica cultivars were core breeding parents with high yield and the other three were super-high-yield varieties registered by the Ministry of Agriculture of China. We constructed nuclear substitution lines to further demonstrate whether and how this indica-type cytoplasm contributed to yield improvement by comparing yield components. The results showed that under the same japonica nuclear background, the lines with indica-type cytoplasm had a significant decrease in tillers in exchange for increased grain number per panicle compared with their recurrent parents. Our results implied that botanical basis of this cytoplasmic effect was to reduce the plant's branching differentiation to produce more floral organs under the constant nutrition. Our findings open another door for the utilization of inter-subspecific hybridization for the improvement of rice cultivar.     

杂交粳稻F2代一粒双苗的倍性鉴定

从杂交粳稻3优18等8个组合的F2代中筛选一粒双苗,并对存活的双苗进行根尖染色体数目和花粉育性的观察鉴定。结果表明：在127610粒3优18F2种子中筛选到双苗16株,双苗率为0．0125％。获得的一粒双苗分为Z-A型和Z-a型两类,每苗都有独立的根系。Z-A型双苗中,Z苗和A苗的根尖染色体数目都是24;Z-a型双苗中,Z苗的根尖染色体数目是24,a苗的根尖染色体数目为12。Z-A型双苗中,Z苗和A苗植株的花药内充满了花粉粒,Z苗植株花粉完全可育,结实正常,A苗植株花粉50％可育,50％不育,与F1相同,结实正常;Z-a型双苗中,Z苗植株花药花粉和Z-A型的Z苗一样,a苗植株花药瘦小,没有花粉粒,自交不结实。     

粳稻品种间种子贮藏蛋白多态性分析

用十二烷基硫酸钠聚丙烯酰胺凝胶电泳方法对115个不同生态型粳稻品种种子贮藏蛋白多态性进行了分析.根据相对分子质量为65×103带的有无,70×103、60×103、57×103、37×103～39×103、22×103～23×103、13×103 、10×103带染色的深浅, 35×103带迁移的速率,及57×103位置带的数量这4种蛋白谱带变异,共鉴别出19种蛋白图谱类型.品种间蛋白谱带相似系数范围在0.75～1.00之间,采用类平均法进行聚类分析,在相似系数0.894处明显地可以将供试品种分为3组:第1组为8个高直链淀粉含量的品种;第2组为15个高贮藏蛋白含量的品种;其他92个品种为第3组,占供试品种的80%.除了中熟中粳生态型与高直链淀粉含量组有关联外,依据熟期划分的生态型与依据贮藏蛋白聚类分析划分的组之间没有明确的关联.     

Determination of Amylose Content and Its Relationship with RVA Profile Within Genetically Similar Cultivars of Rice(Oryza sativa L.ssp.japonica)

Anther culture pure lines with antisense Wx gene were generated by Agrobacterium tumefaciens-mediated co-transformation followed by anther culture in transgenic rice(Oryza sativa L.ssp.japonica).The antisense Wx transgenic pure lines were used to analyze the differences and the relationship between RVA eigenvalues among the lines with different amylose contents.77 pure lines of anther culture having antisense Wx gene were studied for the amylose content of its offspring cultivar,Wuyunjing 7.It was found that levels of amylose content were similar to the control in 19 lines(16.0%);1-5% lower than control in 50 lines,of which,within 11.0-13.9% in 40 lines;and 3.1-4.0% in 8 lines.The effect of the amylose content on RVA eigenvalue was analyzed through the RVA profile graphic comparison and test of significance for RVA eigenvalues.The analysis of RVA profiles with different amylose contents indicated that there were two kinds of RVA profiles within genetically similar cultivars.The lines with 3.1-4.0% of amylose content were distinctly different from other lines and conventional glutinous rice.The comparison of the similarity curve of RVA profile of the lines with different amylose contents showed that the lines with lower amylose content had a distinguished RVA profile with the curve increasing gradually,but not exceeding the first apex.The test of significance for eigenvalues of the RVA profile in the lines with different amylose contents indicated that there were five eigenvalues remarkably different among the lines with 3.1-4.0% of amylose content compared with other two groups.Further,there were three eigenvalues remarkably different among the lines with 11.0-13.5% of amylose content compared with control group.An optimized mathematical model,which characterizes the relationships between the amylose content and RVA eigenvalue,has been established in this study.From this model,it was clearly indicated that the parameters PeT and SBV were more related to amylose content.It was concluded that the differences in amylose content not only affected the eigenvalues of RVA but also caused different RVA profiles within genetically similar cultivars.The introduction of antisense Wx gene could lead to reduce the amylose content and lay theoretical foundation for quality improvement in rice breeding programs.     

Determination of Amylose Content and Its Relationship with RVA Profile Within Genetically Similar Cultivars of Rice (Oryza sativa L.ssp.japonica)

Anther culture pure lines with antisense Wx gene were generated by Agrobacterium tumefaciens-mediated co-transformation followed by anther culture in transgenic rice (Oryza sativa L.ssp.japonica).The antisense Wx transgenic pure lines were used to analyze the differences and the relationship between RVA eigenvalues among the lines with different amylose contents.77 pure lines of anther culture having antisense Wx gene were studied for the amylose content of its offspring cultivar,Wuyunjing 7.It was found that levels of amylose content were similar to the control in 19 lines (16.0%);1-5%lower than control in 50 lines,of which,within 11.0-13.9% in 40 lines;and 3.1-4.0% in 8 lines.The effect of the amylose content on RVA eigenvalue was analyzed through the RVA profile graphic comparison and test of significance for RVA eigenvalues.The analysis of RVA profiles with different amylose contents indicated that there were two kinds of RVA profiles within genetically similar cultivars.The lines with 3.1-4.0% of amylose content were distinctly different from other lines and conventional glutinous rice.The comparison of the similarity curve of RVA profile of the lines with different amylose contents showed that the lines with lower amylose content had a distinguished RVA profile with the curve increasing gradually,but not exceeding the first apex.The test of significance for eigenvalues of the RVA profile in the lines with different amylose contents indicated that there were five eigenvalues remarkably different among the lines with 3.1-4.0% of amylose content compared with other two groups.Further,there were three eigenvalues remarkably different among the lines with 11.0-13.5% of amylose content compared with control group.An optimized mathematical model,which characterizes the relationships between the amylose content and RVA eigenvalue,has been established in this study.From this model,it was clearly indicated that the parameters PeT and SBV were more related to amylose content.It was concluded that the differences in amylose content not only affected the eigenvalues of RVA but also caused different RVA profiles within genetically similar cultivars.The introduction of antisense Wx gene could lead to reduce the amylose content and lay theoretical foundation for quality improvement in rice breeding programs.     

杂交水稻品种指纹鉴定研究进展

从蛋白质指纹和DNA指纹两个方面,综述了杂交水稻品种指纹鉴定研究的进展和不足。对SSR标记在品种指纹鉴定上的应用前景,单一特异标记的筛选和实验室标准检测技术的建立作了探讨和展望,以利于加快杂交水稻品种指纹鉴定的发展和应用。     

我国杂交粳稻育种的现状与展望

本文回顾了我国杂交粳稻育种的历史和现状,分析了目前所存在的问题及其原因,并提出了解决这些问题的可能途径和方法,且对杂交粳稻的发展趋向进行了讨论。     

水稻品种休眠特性的研究

以13个水稻主裁品种及11个F1代抽穗后35d的种子为材料，进行种子休眠特性的研究。结果显示，30℃下，种子未去颖壳时，南京11、桂朝2号等品种的发芽率均高于80％，无休眠性；IR36的发芽率仅为19％，具有较强的休眠性；越光、N22的发芽率分别为2％和0％，具有极强的休眠性；F2代种子的发芽率均不超过亲本（越光除外）。除去种子颖壳后，大多数供试材料的发芽率均显著提高，休眠性丧失，尤其是F2代种子，但N22仍保持极强的休眠性。淀粉酶海性测定结果表明，酶活性与种子休眠性呈负相关。内源激素的分析表明，在吸水之前，不同休眠性品种的内源ABA和GA3含量无明显差异，但吸水后，休眠性与GA3／ABA的比值呈负相关。     

粳稻新老品种株型性状比较

选用日本、韩国、中国的粳稻品种30个,将1990年及以前育成的品种称为老品种,1991年及以后的品种称为新品种。比较新老品种株型性状的变化及其对产量的效应。结果表明：(1)新品种比老品种株高低,穗角小,单株有效穗数少,每穗总粒数多,着粒密度大;新品种比老品种倒2叶基角大,倒3叶基角和张角小,倒3叶叶长短。(2)新老品种的10穴产量,穗总粒数,穗角及着粒密度差异极显,新老品种剑叶、倒2叶和倒3叶的叶宽差异极显。(3)根据通径系数,老品种中穗总粒数、单株有效穗数对产量的直接作用较大;新品种中经济系数、穗总粒数对产量的直接效应较大。新老品种中着粒密度对产量的间接效应总和都为最大。新老品种的倒2叶宽对产量的直接效应较大。老品种的剑叶宽和剑叶基角对产量的间接效应总和较大;新品种的倒3叶宽和倒3叶基角对产量的间接效应总和较大。     

用农杆菌介导法将大豆球蛋白基因导入水稻

在克隆水稻谷蛋白基因Gt1启动子的基础上,以农杆菌双元载体pCAMBIA1301为起点,构建出以该启动子带动大豆球蛋白A1aB1b亚基基因表达的双元载体,并用农杆菌介导法转化水稻获得转基因植株.经PCR检测和后代分析,大豆球蛋白基因已整合入水稻基因组,并在后代中稳定遗传.     

杂交粳稻与纯系粳稻收获指数比较研究

在南京和洪泽两地研究了５个杂交粳稻及其亲本和３个纯系粳稻的生物量、稻谷产量和收获指数。结果表明,当杂交粳稻的亲本包括在纯系粳稻内,杂交粳稻的生物量、稻谷产量极显著地大于纯系粳稻,而收获指数相反;当亲本不包括在内,杂交中熟中粳的生物量虽极显著地大于生产上栽培的纯系粳稻,但因收获指数相反,两者平衡后,稻谷产量无显著差异。生产上栽培的纯系粳稻生物量、稻谷产量和收获指数均极显著地大于杂交粳稻亲本。纯系矮秆粳稻的收获指数极显著地大于中秆粳稻,生物量极显著地小于中秆粳稻,稻谷产量无显著差异。粳稻保持系的生物量、稻谷产量极显著地大于粳稻恢复系,收获指数相反。     

粳稻一次枝梗数和二次枝梗数的遗传分析

2005年和2006年调查了粳稻品种丙8979与C堡及其杂交后代通过一粒传衍生的重组自交系群体（F7：8和F8：9）370个株系主茎穗一次和二次枝梗数的表型分布,并运用主基因＋多基因混合遗传模型对这2个性状进行了遗传分析。结果2年的数据均显示,一次枝梗数性状受2对连锁主基因控制,同时存在多基因,主基因遗传率分别为66％和40％,多基因遗传率分别为11％和41％;二次枝梗数性状均受2对独立主基因控制,同时存在多基因,主基因遗传率分别为80％和65％,多基因遗传率分别为10％和12％。     

不同株高粳稻氮素累积和转运的基因型差异

以矮秆粳稻4007、武运粳和高秆粳稻豫粳和云粳为材料,研究了不同株高水稻累积和转运氮素的基闪型差异。结果表明,4007和武运粳的产量显著高于豫粳和云粳。矮秆粳稻4007和武运粳在分蘖期累积的氮素量低于豫粳和云粳,开花期后吸收的氮素显著高于豫粳和云粳。矮秆粳稻转运到籽粒中的氮素转运量和转运率以及籽粒氮素产量均显著高于高秆粳稻,而成熟时残留在茎叶中的氮素低于高秆粳稻。上述结果表明,种植矮秆粳稻更有利于水稻高产和提高氮素的利用效率。