Environmental Factors Undermine Genetic Expression of Tiller Dynamics in Wild Rice <i>Oryza nivara</i>and <i>Oryza rufipogon</i>

Tillering is a principal trait for the study of branching and production of more number of panicles for increased grain production in many cereal crops. Most of the semi-dwarf high yielding rice cultivars exhibit a remarkable degree of stability with respect to their tillering ability and maintain almost a constant tiller number which is genetically fixed for a particular cultivar. However, tiller production in wild species of rice is largely determined by environmental parameters, which supersede genetic features for expression of complete tillering ability. Two species of wild rice like Oryza nivara and Oryza rufipogon were tested for influence of manipulated growing conditions on tiller dynamics by comparing their growth in natural habitats and cemented pots filled with manure added soil. The results revealed a significant enhancement in the number of tiller production as well as biomass accumulation of each tiller with more grain yield in the cultivated conditions in both the species in comparison to the wild situations. The dryland inhabitant O. nivara became mono-tillering and deep water species O. rufipogon produced as many as five tillers with relatively lesser grain yield in their natural environments compared to their cultivated counterparts. From these observations, it is concluded that expression of genetic potential for tiller production is amenable to fluctuation of environmental factors in the wild species of rice and their capacity for adaption to inclement growth conditions.

尼瓦拉野生稻(Oryza nivara)小粒基因GS3-N的克隆及功能分析

水稻粒型是影响产量的一个重要因素,为挖掘和利用野生稻中粒型相关基因并解析其功能机制,本研究以尼瓦拉野生稻(Oryza nivara)为供体亲本,粳稻品种‘滇粳优1号’(DJY1)为轮回亲本,构建了一个极小粒近等基因系NIL-J155。图位克隆获得了尼瓦拉野生稻中负调控籽粒大小的GS3基因的一个新的单倍型,命名为GS3-N(GS3 from O.nivara)。GS3-N定位在细胞膜,且在不同生长阶段的不同组织中均有表达。序列分析表明,小粒单倍型GS3-NJ155第5个外显子处有312 bp的插入和缺失,其编码的蛋白含有植物特有的器官大小调控区(OSR)和跨膜结构域,而大粒单倍型GS3-NDJY1由于第2个外显子处的无义突变,导致编码蛋白只含有部分OSR结构域。进一步的研究表明,在J155背景下分别敲除OSR和跨膜结构域都能显著增加其粒长和粒重,过表达植株则表现粒长明显变短,株高降低,穗长变短,证明GS3-N可能具有一因多效的作用。本研究结果表明作为调控粒长的负调节子,GS3-N编码蛋白和转录表达水平的差异是引起J155和DJY1粒型差异的原因,这不仅为水稻粒型驯化机制提供新的理论基础,还将为现代水稻栽培种提供更多的粒型遗传资源。

转基因水稻与野生稻(Oryza nivara Sharma et Shastry)杂交后代种子萌发率

种子休眠性是野生植物重要的适应性状,通过种子萌发实验可以分析种子休眠性强弱.通过人工杂交获得转抗虫基因栽培稻与一年生普通野生稻三种组合的杂种,对杂种的F3代和F4代种子采用直接萌发、打破休眠后萌发、埋土15 d和30 d 4种不同处理来检测种子活力和萌发率.结果显示转基因杂种后代种子表现出较强的休眠性,转基因对种子活力和休眠性没有明显的影响,种子休眠性有随种子世代的增加而逐渐减弱的趋势,提示水稻转基因逃逸后有在野生稻群体中宿存和扩散的可能性,但这种可能性可能会随世代增加而下降.这为进一步研究水稻转基因逃逸风险提供了参考.

Molecular Mapping of QTLs for Yield and Yield-Related Traits in Oryza sativa cv Swarna × O. nivara (IRGC81848) Backcross Population

Advanced backcross QTL analysis was used to identify QTLs for seven yield and yield-related traits in a BC2F2 population from the cross between a popular Oryza sativa cv Swarna and O. nivara IRGC81848. Transgressive segregants with more than 15% increased effect over Swarna were observed for all the traits except days to heading and days to 50% flowering. Thirty QTLs were detected for seven yield and yield-related traits using interval and composite interval mapping. Enhancing alleles at 13 (45%) of these QTLs were derived from O. nivara, and enhancing alleles at all the QTLs for stem diameter and rachis diameter were derived from O. nivara. Three stem diameter QTLs, two rachis diameter QTLs and one number of secondary branches QTL identified by both Interval and composite interval mapping contributed more than 15% of the total phenotypic variance. The QTL epistasis was significant for stem diameter and plot yield. The most significant QTLs qSD7.2, qSD8.1 and qSD9.1 for stem diameter, qRD9.1 for rachis diameter and qNSB1.1 for number of secondary branches are good targets to evaluate their use in marker-assisted selection. O. nivara is a good source of novel alleles for yield related traits and reveals major effect QTLs suitable for marker-assisted selection.

Yield Traits and Associated Marker Segregation in Elite Introgression Lines Derived from O. sativa × O. nivara

Introgression lines(ILs)derived from interspecific crosses are a source of new genetic variability.A total of 55 ILs derived from two crosses Swarna×O.nivara IRGC81848(population A)and Swarna×O.nivara IRGC81832(population B)were characterized for yield and yield-related traits/QTLs.Segregation of 103 simple sequence repeat(SSR)markers associated with yield-related QTLs was studied.Population A showed an average of 12.6%homozygous O.nivara alleles and population B showed 10.6%.Interestingly,three SSR markers,RM223,RM128 and RM517,showed conspicuous pattern of segregation.The distribution of parental alleles at three loci RM223,RM128 and RM517 linked to yield-related traits was unique.These markers flanked to several yield-related QTLs.RM223,flanking to qyld8.3,was heterozygous in almost all the 55 ILs except in IL10-3S and IL131S.RM128 on chromosome 1 and RM517 on chromosome 3 were mutually exclusive in 46 out of 55 ILs.These 46 ILs showed either of the marker allele RM128 or RM517 from O.nivara but not both.IL166S had both RM128and RM517 from O.nivara and the other ILs showed homozygous Swarna allele at RM517 except IL65S.Population structure assigned the 55 ILs to three sub-populations based on their genomic diversity.IL65S,IL166S,IL248S,IL7K and IL250K showed high yields in multi-location trials,and IL248S was released for cultivation as DRRDhan 40.

尼瓦拉野生稻内生菌多样性和促生作用

为从尼瓦拉野生稻（Oryza nivara）中收集农业微生物肥料生产的菌种资源,对其内生菌进行分离、固氮酶活性测定、IS-PCR指纹图谱聚类、产生长素、解钾能力及生理生化特性测定.选取IS-PCR指纹图谱8个类群的代表菌株进行16S rRNA基因系统发育分析.从尼瓦拉野生稻中共分离到57株内生细菌,其中44株为内生固氮菌,固氮酶活性在5.79-899.72 nmol mL^（-1） h^（-1）之间.16S rRNA基因序列分析及生理生化特性表明,所分离的植物内生菌属于Burkholderia contaminans、Herbaspirillum seropedicae、Rhizobium sp.、Bacillus methylotrophicus、Achromobacter xyosoxidan、Chryseobacterium bernardeti、Pseudomonas beteli和Klebsiella quasipneumoniae,表明尼瓦拉野生稻内生菌具有多样性.分离到的内生细菌均有产生长素的能力,其中N8、N35、N36产生长素能力最强,分别为41.66、34.96、30.41 mg∕L.25株菌株具有不同程度的解钾能力,N37、N16解钾能力最强,分别为312、289 mg/L.N8、N35、N36、N37、N16接种生菜后,生菜株高增加12.47%-26.17%、叶片数增加20.41%-44.90%、叶长增长49.73%-62.23%、地上鲜重增加37.93%-68.00%、地下鲜重增加31.08%-40.56%、叶绿素含量增加27.94%-85.29%.接种菌株N37、N16的土壤与对照组相比,土壤速效钾含量分别增加52.55%和57.85%,表明菌株具有明显的促生效果.综上所述,从尼瓦拉野生稻中筛选到的5株多功能促生菌在未来农业微生物肥料生产应用上具有潜在的价值.

The Puzzle of Rice Domestication

栽培米饭的起源难倒植物生物学家十年了。Thisis 到期，至少部分地到在米饭栽培变种和野祖先的复杂进化动力学，特别地快速的适应区别和连续基因怜在以内并且在之间栽培并且野米饭。在栽培米饭的单个对多重、年度对长期的起源上的长期的争吵与基因、种系发生的数据的快速的累积被带进 shaper 焦点。分子的种系发生的分析揭示了在米饭栽培变种之间的 ancientgenomic 区别，建议他们从分叉的野人口被驯养。然而，最近克隆的驯服基因 sh4，为谷物粉碎从的 ther 引出负责对栽培米饭野，似乎发源仅仅一次。此处，我们建议二个模型显然调解关于米饭驯服冲突证据。snow-balling 模型考虑栽培米饭的单个起源。在这个模型，批评驯服等位基因的一个核心在成立栽培变种被修理然后行动了与野人口通过杂交增加栽培变种的基因差异。Thecombination 模型考虑栽培米饭的多重起源。在这个模型，起始的栽培变种从分叉的野人口被驯养并且修理了驯服等位基因的不同集合。在这些驯养半的栽培变种之中的随后的十字在当代的栽培变种导致了批评驯服等位基因的一个类似的集合的固定。在两个模型，基因渗入在米饭驯服起了一个重要作用。最近并且从通过常规、分子的繁殖节目的野基因库的有益的基因的未来基因渗入能被看著名计算机生产厂商他驯服的继续……