水稻籽粒伸长突变体lgdp的鉴定与基因定位

Identification and gene mapping of long grain and degenerated palea(lgdp)in rice(Oryza sativa L.)

水稻粒形与产量和营养品质密切相关,挖掘水稻粒形发育相关基因并解析其分子机制,对提高水稻产量、改善籽粒营养品质具有重要意义。利用甲基磺酸乙酯(ethyl methanesulfonate,EMS)处理籼稻品种西大1B,获得了1个水稻粒形突变体,命名为long grain and degenerated palea(lgdp)。lgdp表现出外稃伸长,从而导致籽粒长度增加的特征,进一步扫描电镜分析发现,lgdp籽粒变长主要原因是其外稃细胞数目极显著增加。遗传分析表明该性状受1对隐性基因调控;利用lgdp与ZH11杂交构建的F2分离群体,通过BSA法将目标基因定位在3号染色体分子标记ZLN43和ZLN-1之间,物理距离大约810 kb。通过转录测序和PCR分析初步确认LGDP候选基因编码一个MADS-box基因。qPCR分析表明,LGDP可能通过负向调控GW7/GL7、GS3、TGW6等水稻粒长正向调控因子的表达,从而影响了颖壳细胞数目的增殖,进而影响籽粒长度。本研究结果为应用LGDP基因改良水稻粒形提供了新的资源。

The grain shape,which consists of grain length and grain width,is the primary determinant of grain yield and one of the important appearance quality traits in rice.It is of great significance to identify the related genes associated with grain shape and to study molecular mechanisms for improving the yield and quality of rice.In this study,a long grain mutant named long grain and degenerated palea(lgdp)deriving from EMS(ethyl methane sulfonate)mutation groups of Xida 1B was reported.In lgdp mutant,the elongation of lemma resulted in a long grain.Further SEM analysis revealed that the main reason for lemma elongation was the extremely significant increase in the number of glume cells.Genetic analysis showed that the lgdp trait was regulated by a pair of recessive genes.Using BSA method and the F2 population crossing lgdp with ZH11,the target gene was located between the molecular markers ZLN43 and ZLN-1 on chromosome 3,with a physical distance of about 810 kb.The analysis of RNA-seq and PCR indicated the LGDP candidate gene might encode a MADS-box protein.The qPCR referred that LGDP negatively regulated the relative expression levels of several positive grain length regulatory factors,GW7/GL7,GS3,TGW6,which affected the cell proliferation of glumes and the grain length.The results of this study laid a foundation for the molecular function analysis of LGDP gene in the future.