控制水稻库、源性状SS2基因的克隆及其等位基因多样性分析

Mining functional genes controlling sink and source traits using molecular technology is of great significance in rice breeding for high yield potential. However, little has been reported on cloning gene relevant to sink-source traits in rice. Our previous study indicated that a major gene, SS2, affecting flag leaf length (source trait) and spikelet number per panicle (sink trait) was delimited into a region of 57.3Kb on chromosome 3.New recombinants were identified within this region. We developed near-isogenic lines, SS2-NIL carrying the target QTL region (57.3Kb) introgrssed from Teqing in Lemont genetic background.On the basis, we will take effort to narrow down the location of SS2 to a 30kb region by further high-resolution mapping.Combined bioinformatic analysis,sequencing and expression analysis, candidate genes will be speculated. We will validate effect of SS2 by Agrobacterium-mediated transformation.Further,yield potential and breeding value,haplotype diversity and evolutionary characteristics of SS2 will be studied using SS2-NIL and germplasms collected,respectively.In addition,we will develop a set of functional molecular markers based on the allelic variation at different loci within SS2 for MAS in rice breeding project.These results will play an important role in guiding molecular breeding for developing super high yield rice varieties with ideal plant type and harmony between sink and source, and also lay a foundation for further research gene function.

应用现代生物技术，寻找与库、源性状相关的功能基因对水稻高产育种具有重要的应用价值。但迄今为止，很少有同时控制水稻库、源性状基因克隆的报道，为此，项目组前期精细定位了同时影响水稻库、源性状基因SS2 (57.3Kb) ，获得了该目标区段内的新的重组体，并培育带有影响剑叶长度和每穗粒数的近等基因系。在此基础上，利用重组体的基因型结合表型值对目标基因进行高精确度的连锁分析，力争将SS2基因精细定位到30kb以下；结合生物信息学、基因测序和RT-PCR分析，预测候选基因，利用农杆菌介导的遗传转化对候选基因进行功能验证，评估该基因的产量潜力和育种价值，分析种质资源中的SS2基因的单倍型多样性及其进化特点，开发功能性分子标记。研究结果对通过分子育种技术培育库、源协调的超高产水稻品种具有重要的指导作用，也为进一步深入开展SS2基因的功能研究奠定基础。

应用现代生物技术，寻找与库、源性状相关的功能基因对水稻高产育种具有重要的应用价值。但迄今为止，很少有同时控制水稻库、源性状基因克隆的报道，为此，项目组将同时影响水稻库、源性状基因SS2（GNP1）精细定位到第3染色体SL65-SL54之间的33.7kb物理区间内，结合生物信息学、序列分析以及T-DNA突变体表型考察分析，预测LOC_Os03g63970为候选基因。并利用农杆菌介导的遗传转化对GNP1 基因的候选基因进行了功能验证。GNP1基因编码一个赤霉素20-氧化酶（OsGA20ox1），参与赤霉素信号调控。超量表达GNP1的转基因株系与对照材料中华11相比，增加穗粒数26.5%～36.3%，同时增加剑叶叶长48.2%～52.6%。我们培育得到分别携带有目标染色体区段（66.1 kb）为GNP1特青和Lemont等位基因而其它背景完全为Lemont的近等基因系NIL-GNP1TQ和NIL-GNP1LT。与近等基因系NIL-GNP1LT相比，NIL-GNP1TQ增加剑叶叶长约35%，增加总穗粒数约56%和实粒数约28%，最终导致了NIL-GNP1TQ在多地小区试验中稻谷产量增幅5.7～9.6%，表明GNP1在作物高产育种中有应用价值。对204份栽培稻种质资源和4份野生稻资源的GNP1基因进行了全基因组的深度测序，共发现了15种GNP1单倍型。其中Hap7籼稻单倍型的种质资源拥有最多的每穗粒数和中等程度的株高，这种优异单倍型可以被应用于水稻育种中。本项目研究结果对通过分子育种技术培育库、源协调的超高产水稻品种具有重要的指导作用，也为进一步深入开展GNP1基因的功能研究奠定基础。