| Rice（Oryza sativa L.）is an important food crop in the world.Leaf is the most important organ for plant photosynthesis,and it is also an important reference character for plant type breeding.In recent years,the research on the two aspects of ideal plant type breeding and plant“source-flux-sink”coordination has been deepened,and the yield of rice has been increased by increasing the efficiency of photosynthesis,transportation and storage.In order to further understand the regulation mechanism of rice leaf type,based on the QTL-SPNL7（small panicle and narrow leaf 7）was mapped in the region of 8Mb on chromosome 7,we constructed segregated populations for fine mapping,candidate gene analysis and protein function prediction,as well as tissue cell observation.The main results are as follow:1、We constructed a near isogenic line NIL-spnl7 and its isolation population from WYJ3,which is a receptor parent,and used it as research materials.Compared with the backcross parent WYJ3,the number of large vascular bundles decreased significantly and the number of small vascular bundles decreased significantly in the leaves of NIL-spnl7,which led to the narrowing of the leaves.2、Using database to design and screen SSR and Indel polymorphic markers,we analyzed genotype of the segregating population NIL-F2 crossed WYJ3 with NIL-spnl7,and obtained recombinants.Combined with their phenotypes,allele SPNL7 was fine mapped to the region of 16kb between M3 and Indel6 markers on chromosome 7,which was further confirmed by the progenies of the recombinants.3、Through the analysis of gene sequence alignment and expression in the candidate region,LOC＿Os07g23944 was speculated as the target gene.LOC＿Os07g23944 encodes a member of the glycosylhydrolase family 31,which has an activation site and a carboxylation domain dependent on vitamin K.It was found that the SNP mutation in the coding region of the allele of SPNL7 in NIL-spnl7 resulted in the substitution of glycine for serine at third amino acids in the front of the activation site.Therefore,it is speculated that the mutation affects the activation of SPNL7 protein,leading to functional defects,thereby affecting vascular development and leaf morphogenesis. |
