摘要
高产优质是水稻研究的重要目标,水稻产量由单株穗数、每穗粒数、结实率和千粒重等因素决定,而粒长、粒宽和粒厚是影响千粒重的三要素。本研究中,我们克隆到一个影响水稻粒形的基因OsRAMOSA2,通过遗传转化方法,分别获得了OsRAMOSA2基因表达下调(dsRNAiOsRA2)转基因植株和超表达(pUbi::OsRA2)转基因植株。dsRNAiOsRA2转基因种子长宽比增加,粒厚和千粒重降低;而pUbi::OsRA2转基因种子长宽比减小,粒厚及千粒重增加。利用原位杂交的方法揭示出Os RAMOSA2在未成熟种子的幼胚、胚乳、种皮、背部维管束、珠心表皮、珠心突起处、幼胚内的盾片、胚芽、胚根、胚芽鞘、胚根鞘、外胚芽中均有表达。野生型‘ZH11’种子的胚乳细胞中,淀粉粒呈现多面体,形状均一、排列紧密;而在ds RNAi OsRA2转基因种子中,胚乳细胞的淀粉粒变为球状,排列松散。淀粉合成途径中关键酶类编码基因OsSSIIa、OsGBSSI和OsSSIVb在dsRNAiOsRA2转基因植株中的表达被上调,而在pUbi::OsRA2转基因种子中的表达被下调;pUbi::OsRA2转基因种子中的表观直链淀粉含量(apparent amylose content,AAC)相比‘ZH11’显著降低,而dsRNAiOsRA2转基因种子的AAC显著增加。说明OsRAMOSA2可能通过调控淀粉合成途径中关键基因的表达影响籽粒内直链淀粉的合成积累过程进而正调控粒重。
Rice research is aimed to improve the yield and the quality of the grain. The number of panicle per plant, grains per panicle, the efficiency of seed setting and 1000-grain weight contribute mostly to grain yield, while seed length, seed width and seed thickness determine 1000-grain weight. Here, we reported the cloning and functional characterization of rice OsRAMOSA2 gene which could influence grain size. We constructed dsRNAiOsRA2 and pUbi：：OsRA2 plasmids, and genetically transformed them into wild type ＇ZH11＇ （Oryza sativa L. subsp.japonica） respectively, dsRNAiOsRA2 transgenic plants displayed increased length-to-width ratio in the seeds, reduced grain thickness and 1000-grain weight; while pUbi：：OsRA2 transgenic plants showed reduced length-to-width ratio in the seeds, increased grain thickness and 1 000-grain weight. In situ hybridization revealed that the OsRAMOSA2 transcript accumulated in embryo, endosperm, pericarp, dorsal vascular bundle, nucellar epidermis, nucellar projection, scutellum, shoot, coleoptile, radicle, coleorhizae and epiblast of immature seeds. In ＇ZH11＇ endosperm, the starch granules were uniformly sized and compact; in contrast, those of the dsRNAiOsRA2 transgenic plants were round and loosely packed in the endosperm. Expression of several genes in starch biosynthesis including OsSSIIa, OsSSIVb and OsGBSSI were up-regulated in dsRNAiOsRA2 transgenic plants while down-regulated in pUbi：：OsRA2 transgenic plants. The apparent amylose content （AAC） of dsRNAiOsRA2 transgenic plants increased while the AAC ofpUbi：：OsRA2 transgenic plants reduced. These results suggested that OsRAMOSA2 might be involved in the biosynthesis of amylose through influencing the starch synthesis genes to promote grain weight.
出处
《植物生理学报》
CAS
CSCD
北大核心
2015年第3期307-316,共10页
Plant Physiology Journal
基金
转基因生物新品种培育重大专项(2011ZX08009-003-003)
"十二五"农村领域国家科技计划(2012AA10A302-2)
