Sequence Variation Of Rf-1PCR Segments And Segregation Distortion In Rice Caused By Altitude And Cytoplasm

Rice is one of the most important crops, and it is a model plant in molecular biology. Restorerfertility gene (Rf) is the key gene for cytoplasmic male sterility used in hybrid rice production. Rf-1isthe first one of Rf genes studied systemically and cloned. Rf genes exist only in wild rice and indica ricethat grow in tropical and subtropical region, but don’t exist in japonica rice germplasm fitting templateregions. Studies on sequence variation at Rf-1locus in rice germplasm and on genotype segregationdistortion at Rf-1locus caused by altitude and cytoplasmic factors would helpful for understandingevolution of Rf genes in rice, also helpful for clarifying relationship between Rf genes andindica-japonica differentiation of different altitude condition.Based on68923-8primer located on Rf-1locus, PCR fragment sequences in wild rice, indica andjaponica rice were analyzed and to indicated sequence variation in rice, further study evolution of Rfgene sequentially. Segregated populations generated from crosses between Nan34and C418possessedRf-1gene and Xiaohuagu and Xiaomagu possessed non-Rf-1gene, which are two japonica ricelandraces from a high altitude in Yunnan. Geneotype segregation at Rf-1locus of the populationsgenerated at four altitudes (400m、1250m、1890m and2200m) were analyzed by PCR with68923-8primer, also spikelet fertility of the populations were analyzed, to know the effect to geneticdifferentiation of altitude and cytoplasm The main results were as follows:（1）According to phylogeny tree based on DNA fragment sequence at Rf-1locus, all of thegermplasm were divided into two groups, one was consisted of wild rice, indica rice and japonicarestorer lines, and the another one constituted mainly by japonica conventional varieties. The first groupwas consisted mainly by wild and indica lines, and only one indica conventional variety namedDianli401had near relationship with wild rice.(2) Sikelet fertility average value under japonica cytoplasm was larger than indica cytoplasm atmiddle、high altitudes（1890m and2200m）, but at low、middle altitudes（1250m and1890m）, spikeletfertility average value between reciprocal populations distorted to different cytoplasm.(3) On Rf-1locus, as Nan34which has indica cytoplasm was female parent, populations were alldistorted toward Nan34at all altitudes, and the distorted was more serious at middle、high altitude.Under japonica cytoplasm background, only several populations occurred distortion, and thosepopulations was most distorted toward landrice.(4) Under japonica cytoplasm background, differentiation between low altitude and middle-highaltitude was significated, and populations of different generations had difference under indica cytoplasm.Cluster analysis indicated that there were obvious differentiation between indica and japonica cytoplasm,and indica cytoplasm effects on differentiation were modified by altitude variation.(5) Our study first indicate sequence variation on Rf-1locus of different type of rice, and these results could be reference for study indica-japonica differentiation. In addition, it is the first time toshow that genetic structure of populations would be changed by effects from interaction betweenindica-cytoplasm and japonica-nuclei, and then caused genetic differentiation between populations.