亚洲栽培稻与长雄野生稻种间杂种不育基因S44（t）的克隆

Breaking down the interspecific reproductive isolation is one of the accessible approaches to broaden the genetic basis in cultivated rice.There are abundant genetic variations in Oryza longistaminata , which shares the same AA genome with O.sativa, but the exploration and ultilization of favarable genes from O.longistaminata were hampered because of severe hybrid embryo abortion and interspecific hybrid sterility. In this study, near isogenic line with hybrid sterility gene S44(t) (BC6F10) and mapping population (BC7F2) were constructed using O.longistaminata as the donor parent and O.sativa RD23 as the recurrent parent.S44 (t) was located in the region between RM5814 and RM20695 on chromosome 6. Based on those results, map-based cloning，complementation test and expression profile were used to isolate S44(t) and elucidate gene function in the interspecific hybrid sterility between O.sativa and O.longistaminata.This study will shed light on the molecular mechanism of interspecific hybrid sterility and gene divergence in genus Oryza, and will lay the foundation of ultilization of gene pool in O.longistaminata and improvement of rice varieties.

打破种间生殖隔离是拓宽现有栽培稻遗传基础的有效途径之一。长雄野生稻与亚洲栽培稻具有相同的AA基因组，存在丰富的遗传变异，但二者之间严重的杂种胚败育和杂种不育阻碍了长雄野生稻有利基因的挖掘和利用。本研究以长雄野生稻为供体亲本，以亚洲栽培稻RD23为轮回亲本，培育了携带种间杂种不育基因S44(t)的近等基因系（BC6F10）及定位群体（BC7F2），并将该基因定位在第六染色体RM5814和RM20695之间。在此基础上，本项目拟采用图位克隆、互补实验和表达谱分析等方法克隆S44（t）并阐明该基因的功能。本研究将对认识稻属种间杂种不育的分子机制及稻属分化提供重要的参考价值，为长雄野生稻基因库资源的利用及水稻品种改良工作奠定理论基础。

打破种间生殖隔离是拓宽现有栽培稻遗传基础的有效途径之一。克隆种间杂种不育基因有助于野生稻及其近缘种的利用。本项目以亚洲栽培稻籼稻品种RD23为轮回亲本、长雄野生稻为供体亲本，在培育了含有亚洲栽培稻与长雄野生稻种间杂种不育基因S44(t)的近等基因系（NIL）及定位群体的基础上，利用图位克隆的方法将S44(t)基因定位在3个ORF内，目标区段测序结果显示RD23在定位区间内只有一个ORF1（ORF1-RD23），而NIL包含3个ORF，即ORF1（ORF1-NIL）、ORF2和ORF3。将ORF1-RD23和ORF1-NIL分别转化到F1植株中，转基因植株的花粉育性都得到了恢复。F2群体偏分离是由于F1中ORF1-RD23和ORF1-NIL两个等位基因转录水平不同造成的。ORF1-RD23在整个花粉粒中都有表达而ORF1-NIL在花粉壁中不表达；ORF1-RD23定位在质膜和核膜上，而ORF1-NIL定位在细胞质中；以上结果说明ORF1-RD23和ORF1-NIL可能在小孢子发育过程中行使着不同的功能。本研究结果为进一步阐明S44(t)作用于亚洲栽培稻与长雄野生稻种间杂种不育的分子机制奠定了基础。