QTL Mapping Of Fertility In Hybrid Between African Rice (Oryza Glaberrima Steud.) And Asian Rice (Oryza Sativa L.)

Hybrid sterility and introgression of the quantitative trait loci controlling many important agriculture traits are the key constraints during utilization of the Oryza relatives. The African rice(O.glaberrima),compared to O.sativa,is originated independently,and has its own ancestor wild perennial and annual species,but shares common genome AA with 24 chromosomes,and has been used in this study.The fertility of hybrids controlled by QTLs has been used as the study target and the genetics of hybrid sterility in the progenies of O.sativa x O.glaberrima crosses has been studied.At the same time a more efficient method to detecting QTLs has been discussed.Three generations(BC₁F₁,BC₆F₁,BC₇F₁) from the crossCG14/WAB450-16//WAB450-16 were used in our study.Mapping of quantitative trait loci(QTLs) controlling typical, spherical,stained abortion,normal types pollen and spikelet fertility have been carried out using SSR molecular marker.The segregation of highly fertile and partly sterile individuals in the recurrent backcross and the interaction of the fertility loci coming from O. glaberrima have been analysed.There are some new advances comparing with other study published,and the possibility of the major QTLs could be treated as single Mendelian factors using recurrent backcross,recurrent selection and recurrent molecular mapping have been discussed.The main findings of this study are as follows:(1) It is the first report that a fully SSR molecular linkage map constructed using 132 microsatellite markers and 182 individuals derived from O.glaberrima/O.sativa//O. glaberrima interspecific BC1F1population.The genetic map spanned 1938.7cM and the average distance between adjacent markers is 14.7cM.It provides a tool for evaluation and utilization of the potential of O.glaberrima in rice breeding.Using this map,QTLs controlling pollen and spikelet fertility were identified.(2) The BC₁F₁ population had been advanced to the BC₆F₁ according to the variational percentage of pollen grain that could be stained with 1%1-Kl solution and spikelet fertility for the purpose of identifying QTLs for traits related fertility.A "contig lines" molecular map about fertility had been constructed using 143 microsatellite markers and 50 individuals of BC₆F₁ population.The BC₇F₁ advanced backcross population had been developed based on the "contig lines" molecular map.(3) The 10 advanced backcross populations were analyzed on the chromosome heterozygosity regions for the precise location of the fertility locus in the molecular map. We detected four QTLs for pollen and spikelet fertility on chromosomes 1,3,and 7 in the intervals RM443-RM128,RM60-RM3117,RM295-RM481 and RM11-RM10 respectively, whose percentage of explained phenotypic variance ranged from 9%to 57%.There were two QTLs for pollen and spikelet fertility on chromosome 7,and the four new QTLs were named S19,S30(t),S31(t),S32(t),respective.(4) One pair of epistatic QTLs,S31(t),S32(t),was detected on chromosome 1 and 7 in advanced backcross population H3E207,H3E211,H3E228.This conclusion advanced the patterns of one locus sporo-gametophytic interaction model.(5) This study clearly indicated that some major QTLs could be treated as single Mendelian factors in linkage mapping according to the method of recurrent backcross, recurrent selection and recurrent molecular mapping.