CRISPR/Cas9编辑GS3和qGL3基因创制大粒水稻新种质

Creating Novel Rice Germplasms with Enlarged Grain Size by Editing GS3 and qGL3 Genes via CRISPR/Cas9

CRISPR/Cas9基因编辑技术已成为植物新种质创制和性状定向改良的重要手段。GS3和qGL3是调控水稻籽粒伸长的主效基因,功能缺失后产生大粒表型。本研究拟以小粒型粳稻品种南粳5055为试验材料,对GS3和qGL3基因进行编辑,以期获得能稳定遗传的大粒水稻新种质。利用CRISPR/Cas9系统构建了分别携带GS3-gRNA和qGL3-gRNA双靶点的pYLCRISPR/Cas9编辑载体,通过农杆菌介导的遗传转化法,成功获得了GS3和qGL3基因编辑植株,编辑效率分别为90.0%和88.9%。与南粳5055相比,GS3编辑植株在T2、T3世代中平均粒长增幅约9.0%,千粒重增幅平均为12.7%,每穗粒数降低约9.3%,穗数、穗长、结实率和单株产量差异不明显;qGL3编辑植株的粒长增幅约21.0%,千粒重增幅平均为31.7%,每穗粒数降低约31.5%,且穗数表现出增加而结实率表现降低趋势,而穗长和单株产量差异不明显。qGL3基因对粒形和粒重的贡献明显大于GS3。综上所述,通过CRISPR/Cas9技术编辑南粳5055的GS3和qGL3基因,获得了一系列大粒水稻新种质,该结果为水稻粒形改良研究提供了重要参考。

CRISPR/Cas9-guided gene editing technology has become a popular and precision strategy in innovation of new plant germplasms and directional improvement of agronomic traits. The GS3 and qGL3 genes are the major regulating factors contributing rice grain elongation,and loss-of-function mutants result in enlarged grain size. To obtain new inheritable large grain rice germplasms,this study deployed CRISPR/Cas9 genome editing technology to edit GS3 and qGL3 genes in the japonica rice variety Nanjing 5055 showing small grain shape. Through agrobacterium-mediated genetic transformation of pYLCRISPR/Cas9 editing vector that carries GS3-gRNA and q GL3-gRNA,we obtained the GS3-and qGL3-edited plants,with the editing efficiency of 90.0%and 88.9%,respectively. In comparison with the wild-type Nanjing 5055,the GS3-edited lines showed about 9.0%increase on grain length,12.5% increase on 1000-grain weight,as well as about 9.3% decrease on grain number per panicle from the analysis of average values of T2 and T3 generations. Interestingly,there was no significant difference in panicle number,panicle length,seed setting rate and yield per plant. For qGL3-edited lines,ca.21.0% and 31.7% increases on grain length and 1000-grain weight,respectively,and ca. 31.5% decrease on grain number per panicle were observed. An increase on panicle number and a decrease on seed setting rate in qGL3edited lines were detected if compared to those of Nanjing 5055,while no differences on panicle length and yield per plant were found. The contribution of qGL3 gene to grain shape and grain weight was significantly greater than those of GS3. Collectively,this study identified a series of new rice germplasms with enlarged grain size via genome editing of the GS3 and qGL3 genes in Nanjing 5055,which might have significant implications for grain size improvement in rice.