Generation of selectable marker-free soft transgenic rice with transparent kernels by downregulation of SSSⅡ-2  

作　　者：Zhihao Xu Meimei Yu Youwei Yin Cenwen Zhu Wen Ji Changquan Zhang Qianfeng Li Honggen Zhang Shuzu Tang Hengxiu Yu Qiaoquan Liu 

机构地区：[1]Jiangsu Key Laboratory of Crop Genetics and Physiology,Key Laboratory of Plant Functional Genomics of the Ministry of Education,Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding,Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops,College of Agriculture,Yangzhou University

出　　处：《The Crop Journal》2020年第1期53-61,共9页作物学报（英文版）

基　　金：supported by the Key Transgenic Breeding Program of China(2016ZX08001006,2016ZX08001002-003);the National Key Research and Development Program(2016YFD0102000);Yangzhou City Science and Technology Plan(YZ2017059);the National Natural Science Foundation of China(31872859);Jiangsu Agricultural Science and Technology Innovation Fund(CX181001);the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)

摘　　要：The amylose content(AC) of rice endosperm starch varies from 0 to 35%,and is associated with rice cooking and eating quality.Soft rice has low AC,generally between 6% and 15%,and its eating quality is high whether it is consumed hot or cold.However,the appearance quality of current soft rice cultivars needs to be improved,especially opaque endosperm.Conventional genetic engineering has improved some agronomic traits of soft rice varieties,but not endosperm appearance.In the present study,a RNAi construct of the soluble starch synthase Ⅱ-2(SSSⅡ-2) and the hygromycin phosphotransferase(HPT) gene were introduced into an elite japonica rice variety,Kangtiaowuyunjing(KWY8) by co-transformation.Several selectable marker-free(SMF) transgenic lines were obtained,and SSSⅡ-2 expression was significantly downregulated in selected transgenic lines,resulting in lower AC of the endosperm.The physicochemical properties of the transgenic rice kernels,including gel consistency(GC) and rapid visco analyzer(RVA) profile,differed significantly from those of wild-type rice and were similar to those of a soft rice variety,Nanjing 46(NJ46).These findings indicate that the cooking,eating,and processing qualities of transgenic rice are comparable to those of NJ46.However,the transgenic rice endosperm retained a transparent appearance under low-moisture conditions.Thus,SMF SSSⅡ-2 RNAi rice provides a resource for breeding soft rice with transparent endosperm.The amylose content(AC)of rice endosperm starch varies from 0 to 35%,and is associated with rice cooking and eating quality.Soft rice has low AC,generally between 6%and 15%,and its eating quality is high whether it is consumed hot or cold.However,the appearance quality of current soft rice cultivars needs to be improved,especially opaque endosperm.Conventional genetic engineering has improved some agronomic traits of soft rice varieties,but not endosperm appearance.In the present study,a RNAi construct of the soluble starch synthase II-2(SSSII-2)and the hygromycin phosphotransferase(HPT)gene were introduced into an elite japonica rice variety,Kangtiaowuyunjing(KWY8)by co-transformation.Several selectable marker-free(SMF)transgenic lines were obtained,and SSSII-2 expression was significantly downregulated in selected transgenic lines,resulting in lower AC of the endosperm.The physicochemical properties of the transgenic rice kernels,including gel consistency(GC)and rapid visco analyzer(RVA)profile,differed significantly from those of wild-type rice and were similar to those of a soft rice variety,Nanjing 46(NJ46).These findings indicate that the cooking,eating,and processing qualities of transgenic rice are comparable to those of NJ46.However,the transgenic rice endosperm retained a transparent appearance under low-moisture conditions.Thus,SMF SSSII-2 RNAi rice provides a resource for breeding soft rice with transparent endosperm.

关 键 词：Rice(Oryza sativa L.) SSSⅡ-2 RNAi Starch quality SMF transgenic lines 

分 类 号：S511[农业科学—作物学]