【作者】 查笑君；

【导师】 杨金水；

【作者基本信息】 复旦大学 ， 遗传学， 2009， 博士

【摘要】 有效分蘖数、每穗粒数和千粒重是构成水稻产量的三要素。这些因素的变异呈连续分布,呈现数量遗传的特性。这些性状受多个位点(quantitative trait loci,QTLs)的影响,并且它们的表达受环境和遗传背景的修饰。由于其复杂性,只有少部分调控这些性状的基因被分离和证实。先前,我们通过图位克隆的方法从以东乡野生稻(Oryza,rufipogon Griff.)为供体与以桂朝2号(Oryza sativa L.ssp.Indica)为受体的BC4F2群体中获得了一个与水稻高产有关的QTL位点_qGY2-1,试验证明这个QTL位点促进水稻谷粒子增加从而对产量的贡献率达到16%。基因结构分析表明这个QTL位点由LRK1-LRK8(leucine-rich repeat receptor-likekinase,LRK),八个编码富含亮氨酸重复序列型类受体激酶新基因所组成的基因簇。有意思的是东乡野生稻的基因簇中包含LRK1基因,而贵朝2号基因簇中这个基因缺失。所以我们选用东乡野生稻的LRK1基因进行研究,数据显示LRK1在根、茎、叶、幼穗中有都表达;亚细胞定位实验表明LRK1蛋白定位于质膜上。将LRK1基因导入缺失LRK1基因的籼稻9311(Oryza sativa L.subsp.indica vat.9311)中过表达,结果发现过表达LRK1基因降低了株高,促进了细胞分裂和植株生长,提高了水稻有效分蘖数、每穗粒数、二次支梗数,因此我们推测LRK1基因与植株分枝发育有关。最终的统计结果显示LRK1基因提高了水稻的单株产量达58%。水稻因为基因组比较小(390Mb),目前基因组测序已经完成,而成为单子叶植物的模式植物。对LRK1基因功能的分析不仅有利于对水稻产量形成机制的理解,同时也促进对其他作物的产量形成的分子机制的认识。为了验证同一基因簇中其他同源基因是否具有相似的功能,我们选择了LRK6和LRK7构建于不同的表达载体进行过表达研究,研究结果表明LRK6和LRK7具有与LRK1相似的功能,LRK6和LRK7都促进了植物的生长,对水稻有效分蘖数的贡献分别为38.1%,27.86%。单株粒数分别增加了49%,36.36%。LRKs在植物生长发育和抗性反应中起着广泛的调节作用。为了探索LRK1基因在细胞内的互作蛋白,我们将LRK1基因的胞内域构建成诱饵质粒采用酵母双杂的方法筛选籼稻9311的cDNA文库,获得了与LRK1互作的翻译延伸因子eIF-1A(translation elongation factor)蛋白,这种相互作用在酵母中得到了证实,其体内试验还在进行中。我们初步推测LRK1基因通过促进蛋白质翻译发挥其生理功能。更多还原

【Abstract】 In rice (Oryza sativa L.), the number of panicles, spikelets per panicle, and grain weight are important components of grain yield. These characteristics are controlled by quantitative trait loci (QTLs) and are derived from variation inherent in crops. Due to the complex genetic basis of these traits, only a few genes involved in their control have been cloned and characterized. We previously map-cloned a gene cluster including eight leucine-rich repeat receptor-like kinase (LRK) genes in Dongxiang wild rice (Oryza rufipogon Griff.), which increased grain yield by 16%. In the present study, we characterized the LRK1 gene, which was contained in the donor parent (Dongxiang wild rice) genome and absent from the recurrent parent genome (Guichao2, Oryza sativa L. ssp. Indica). Our data show that rice LRK1 is localized in the plasma membrane, encoding a LRK protein, and is expressed constitutively in leaves, young panicles, roots and culms. Over-expression of rice LRK1 results in an increased number of panicles and grains per panicle, a slight change in grain weight, and enhanced cellular proliferation. The increased number of panicles and grains per panicle are associated with increased branch number. Our data suggest that rice LRK1 regulates rice branch number by enhancing cellular proliferation. The functional characterization of rice LRK1 facilitates understanding of the mechanisms involved in cereal crop yield, and may have utility in improving grain yield in cereal crops.In order to conform the other LRK genes in the same cluster, we selected the LRK6 and LRK7 constructed in the different plasmid and delivered to the 9311. The results indicated that LRK6 and LRK7 have the same function as the LRK1. They promoted the plant development and increase the panicles per plant (38.1%, 27.86% separately)and the grains per plant (49%, 36.36% separately).The LRR-RLKs play an important role in diverse plant signal transduction pathways during growth and development. In orde to search the protein interaction with LRK1, we screened which by yeast two-hybrid using the LRK1 kinase domain. The resules revealed eIF-1A interacted with the LRK1 that suggested LRK1 may involved in the protein translation.更多还原