Genetic analysis of dense and erect panicle 2 allele DEP2-1388 and its application in hybrid rice breeding

通过EMS诱变籼型重穗恢复系蜀恢498,获得一个直立穗突变体R1338.与野生型相比,突变体表现为植株变矮、穗直立、穗长变短、一次枝梗变短、着粒密度增加、穗部抗弯曲力极显著增强、籽粒增宽增厚、粒长变短.组织细胞学分析发现,穗颈节直径、纤维素含量和木质素含量在穗部抗弯曲上发挥了重要的作用.遗传分析表明该直立穗表型受一对半显性核基因DEP2控制,通过重测序以及MutMap方法定位发现,在R1338突变体中,DEP2第7外显子有一个A到G的碱基置换,导致第928个精氨酸(AGG)被置换成甘氨酸(GGG),推测R1338直立穗性状可能由DEP2中该SNP导致.用R1338、野生型与不同穗型不育系分别配组,R1338与弯曲穗不育系所配组合穗部表现半直立,且保持较高的结实率和杂种优势,与DEP1直立穗不育系配组表现为基因累加效应的直立穗.本研究还讨论了直立穗突变体R1338在杂交水稻育种中的利用价值.Using ethyl methanesulfonate (EMS) mutagenesis, we isolated an erect panicle mutant, R1338, from indica heavy-panicle restorer Shuhui498. Compared with wild type control, the mutant displayed dwarfism, erect and short panicle, short primary panicle branch, increased grain density, short grain length and increased grain thickness. In addition, the erect panicle architecture of R1388 resulted in significant decreased bending moment and increased resistance to panicle bending. Histocytological analysis indicated that the diameter of uppermost internode, cellulose content and lignin content play important roles in resistance to panicle bending. Genetic analysis revealed that the mutant phenotype was controlled by a semi-dominant nuclear gene. With resequencing and MutMap analysis strategy, we found that one SNP from A to G at the seventh exon of DEP2 resulted in the 928(th) amino acid substitution from arginine (AGG) to glycine (GGG) in R1338 mutant. Considering the phenotype of other dep2 mutants, the phenotype of R1338 was likely to be caused by the SNP in DEP2. The mutant R1338 and wild type were crossed with several sterile lines which respectively had different panicle types, the combinations generated from R1338 and curve panicle sterile lines showed semi-erect panicle, higher seed setting percentage and heterosis, and the combinations generated from R1388 and erect panicle sterile line with DEP1 showed erect panicle by gene additive effect. Moreover, the combinations with semi-erect panicle had superior light transmittance and stronger light intensity, which improved efficiency of light utilization to intermediate and subjacent leaves compared to the combinations with curved panicle. This study provides a good strategy to solve the problem of population density in three-line hybrid rice.国家自然科学基金; 国家科技支撑计划“长江上游优质抗病种质创制与新品种选育”; 四川省生物质资源利用与改性工程技术中心开展开放基金项目和杂交水稻国家重点实验室开放基金项目; Project Supported by the National Natural Science Foundation of China; National Key Technology Support Program ‘Germplasm Creation and New Variety Breeding of High Quality and Disease Resistance in Upper Yangtze River’; the Open Fund of Engineering Research Center for Biomass Resource Utilizaiton and Modification of Sichuan Province,and the Open Research Fund of State Key Laboratory of Hybrid Rice (Hunan Hybrid Rice Research Center)PubMed中文核心期刊要目总览(PKU)中国科技核心期刊(ISTIC)中国科学引文数据库(CSCD)172-813