Identification of QTLs for domestication-related and agronomic traits in an Oryza sativa×O. rufipogon BC1F7 population

Asian cultivated rice was domesticated from the wild rice, Oryza rufipogon and throughout the domestication process, a wide range of morphological and physiological changes altered the ancestral form. This study was conducted to identify the genetic basis of changes associated with the domestication process. An recombinant Inbred line (RIL) population consisting of 120 lines was developed from a cross between the Juponica cultivar.‘Hwayeongbyeo’and a presumed wild progenitor. O. rufipogon Griff. Acc.01944. The population was genotyped with 124 simple sequence length repeat (SSR) markers, providing an average interval size of 15 cM, and also evaluated for 20 traits related to domestication and agricultural performance. A total of 63 quantitative trait locus (QTLs) and one locus associated with qualitative variation for pericarp coloration were identified using single point and composite interval analysis. The number of QTLs per trait ranged from one to seven. Phenotypic variation associated with each QTL ranged from 3.7 to 40.4%. with an average of 15.3%. The results indicated that most domestication‐related traits clustered in chromosomal blocks, and the positions of many of these clusters were consistent with those reported in previous studies and with skewed segregation ratios in these BC₁,F₇ RILs. For 13 (20.6%) of the QTLs identified in this study. the O. rufipogan ‐derived allele contributed a desirable agronomic effect despite the overall undesirable characteristics of the wild phenotype. Favourable alleles from O. rufipogan were detected for panicle length, spikelets per panicle, days to heading and leaf discoloration associated with cold stress. When compared with previous studies involving interspecific crosses, it can be concluded that O. rufipogon is useful as a source of valuable alleles for rice improvement and that many of the introgressed regions contain genes that have a favourable impact on phenotype in different genetic backgrounds and different environments.     

东乡野生稻细胞质雄性不育育性恢复的遗传研究

应用协青早A／（协青早B／／东乡野生稻／协青早B）BC1F5、中9A／（协青早B／／东乡野生稻／协青早B）BC1F5、协青早A/（协青早B／／协青早B／东乡野生稻）Be1F5和中9A／（协青早B／／协青早B／东乡野生稻）BC1F5四套测交群体,分析测交群体的育性表现及研究东乡野稻细胞质雄性不育育性恢复的遗传。结果表明：东乡野生稻对矮败（CMS—DA）和印尼水田谷败育（CMS—IA）的育性恢复表现为质量一数量性状,结合群体遗传结构、育性分布和东乡野生稻的偏粳性及广亲和性,可知东乡野生稻对CMS—DA和CMS—IA的恢复性由1对或2对恢复基因控制。     

2份广西普通野生稻材料育性恢复基因Rf3、Rf4的恢复力评价

影响杂交水稻高产与稳产的重要因素是结实率的高低,而这一特性是由恢复系的恢复基因所决定的。因此,水稻恢复系的选育和利用具有重要意义。本研究以2份广西普通野生稻材料DP32和DP70为供体亲本,以籼稻品种9311为受体亲本,采用连续多代回交和分子标记辅助选择的方法,分别得到携Rf3、Rf4基因座位的5个单片段代换系。选用野败（WA）型细胞质不育系盟抗A和新质源（FA）型不育系金农1A对这5个单片段代换系的恢复能力进行测交鉴定。结果表明：（1）来自DP32的Rf3基因座位的单片段代换系能够恢复盟抗A,而来自DP70的Rf3基因座位的单片段代换系不能恢复盟抗A。（2）来自DP32或DP70的Rf4基因座位的单片段代换系都能恢复盟抗A。（3）来自DP32或DP70的Rf4基因座位的单片段代换系对盟抗A的恢复力均高于其Rf3基因座位的单片段代换系。（4）5个单片段代换系均不能恢复金农1A。本研究结果为在广西普通野生稻中挖掘和利用恢复基因种质提供参考,并且为进一步精细定位Rf3和Rf4基因创建了理想材料。     

Clonal performance of perennial Oryza sativa/O. rufipogon selections and their combining ability with O. sativa cultivars for survival, stolon production and yield

In Southeast Asia, upland rice (Oryza sativa) is an annual crop typically grown for subsistence on hilly lands that are at risk for soil erosion. If perennial cultivars of upland rice were developed, they would provide farmers with an inexpensive tool to produce a preferred food while conserving soil. O. rufipogon, the undomesticated progenitor of O. sativa, includes perennial and stoloniferous forms. To evaluate the feasibility of developing perennial cultivars by combining genes of O. sativa and O. rufipogon, four trials were conducted in an upland field at IRRI: O. sativa/O. rufipogon F₁ clone and cutting height trial, F₂ family trial, and two O. sativa/stoloniferous-selection factorial mating design trials. Plants were established at the beginning of the rainy season, then subjected to a 6-month dry season and evaluated for survival after 1 year. Of the 2101 cultivar control plants, only three IR47686-1-4-B individuals survived and none produced stolons. The 18 F₁ clones, which were selected from previous trials with less drought stress, ranged in survival from 4.4 to 91.4%. Cutting height at harvest did not affect survival. Survival among the F₂ families ranged from 9.4 to 31.9%. Segregation for stolon presence did not differ from a 3:1 ratio for five of the six F₂ families, suggesting the effect of a single dominant gene. Average yields per plant for the F₂ families were 1/3 to 1/9 of yields for the cultivars. However, by crossing the F₁s to cultivars, yield potential was almost fully recovered. For the full-sib families of the factorial trials, survival ranged from 0.0 to 48.6%. Azucena and IR47686-1-4-B, both japonica cultivars, exhibited greater general combining ability for survival relative to the six other cultivar parents. Thus, the process of developing perennial cultivars of rice should include screening annual cultivars to identify those with the best combining ability for survival. To develop cultivars of perennial upland rice, drought avoidance and/or tolerance from annual upland cultivars must be combined with the capacity for perennial growth from wild perennial species. The frequency of stolonifereous testcross progeny was lower than expected and was affected by the O. sativa parent. Thus, additional genes likely affected stolon penetrance and expression. Analyses of covariance indicated that stolons improved the likelihood of survival for progenies of the factorial trials but the effect was small (b < 0.1), and that yield (g/plant) had a small negative effect on percent survival (b = −0.13 to −0.32). This study demonstrated that it was possible to introgress genes for perennial growth from wild O. rufipogon accessions into domesticated O. sativa. Additionally, strategies for developing perennial cultivars of upland rice were improved.     

普通野生稻红色种皮遗传分析及育种利用初探

利用4份红色种皮的广西普通野生稻（Oryza rufipogon Griff.）与白色种皮籼稻品种93-11杂交,获得F1群体,再自交构建F2群体,对种皮颜色进行遗传分析,发现4份普通野生稻的红色种皮对来自93-11的白色种皮性状均表现为显性遗传。通过杂交、回交和多代自交后,将来自普通野生稻的红色种皮性状导入水稻品种93-11,获得多个农艺性状遗传稳定的红色种皮水稻品系。结果表明,通过常规育种手段可以打破红色种皮与不良农艺性状的连锁,利用野生稻红色种皮特性培育营养丰富具有保健功能的有色稻米品种是可行的。     

贵港最大面积原生地新收集普通野生稻分子鉴定评价

为了对来自贵港市最大面积原生地新收集普通野生稻资源进行遗传多样性分析,并在此基础上 进一步对居群内的个体进行区分。选择分布于水稻染色体组的25 对微卫星(SSR)引物对来自贵港的 349 份材料进行多样分析和遗传结构研究。结果表明,所有个体平均等位基因数A=6,有效等位基因数 Ae=2.23,期望杂合度He=0.44,实际杂合度Ho=0.40,香农指数I=0.88。该居群可分为4 个亚群结构,并 且90%以上个体可以得到区分。该群体遗传多样性丰富,SSR分子标记可以简单有效的区分群体内的 大部分个体,提高了保护效率。     

中国普通野生稻遗传多样性研究进展

普通野生稻是亚洲栽培稻的祖先,中国作为亚洲栽培稻的起源地之一,蕴藏着丰富的普通野生稻资源。为了揭示中国普通野生稻的遗传多样性分布状况,探索普通野生稻的遗传变异规律、居群遗传结构以及演化途径等,为亚洲栽培稻的起源进化研究、品种改良和普通野生稻保护提供科学依据,国内外学者对中国普通野生稻开展了大量的遗传多样性研究,获得了丰富的研究结果。本文分别从遗传多样性研究方法、普通野生稻与亚洲栽培稻遗传多样性的比较、普通野生稻遗传多样性与地理分布和生态环境的关系、保护措施和栽培稻基因渗入对遗传多样性的影响等几个方面的研究结果进行了综述,总结了中国普通野生稻遗传多样性的主要特征,提出了未来我国普通野生稻遗传多样性的研究方向。     

利用功能标记鉴定普通野生稻中的白叶枯病抗性基因

 以9个菲律宾白叶枯病菌小种对供试的9份普通野生稻（Oryza rufipogon Griff.）及1份高感白叶枯病材料IR24进行抗性鉴定,发现IR24对所有的菌株都表现为高感, 6份野生稻材料对9个菌株表现全抗,占参试野生稻总数的67%。取自广西玉林的1份材料只感PXO280(P8),海南万宁的1份材料感PXO71(P4),广州高州的1份材料对PXO79、PXO99和PXO339感病,而这几份材料对其余菌株都表现为抗病,说明每份材料至少含有1个抗性基因。利用已克隆的白叶枯病抗性基因xa5、xa13、Xa21和Xa27的功能标记检测,结果表明9份供试普通野生稻中都不含抗性基因xa5、Xa21;5份为显性Xa13纯合体,4份为隐性抗病xa13杂合体;5份为抗病显性Xa27纯合体,3份为隐性xa27纯合体,1份材料中xa27和Xa27都不存在。     

野生稻、野燕麦、枸杞DNA的提取方法

采用CTAB法和2种经改进SDS法提取野生稻、野燕麦、枸杞总DNA。提取结果表明植物的种类不同,所适用的提取方法也有所不同。野生稻和野燕麦DNA提取较合适的方法为SDS-和CTAB法,枸杞DNA提取较合适的方法为SDS-法。