Phenotypic Diversity Of Natural Populations Of Oryza Rufipogon Griff. In China

Common wild rice(Oryza rufipogon Griff.),which is regarded as a wild ancestral species of Asian cultivated rice,contains many novel genes that are important genetic materials for modern rice breeding programs.China has a long history of rice cultivation and has abundant germplasm resources of common wild rice.In this study,we collected the eight natural populations of the common wild rice from Dongxiang,Fogang,Boluo,Zengcheng,Huilai,Gaozhou,Suixi and Qionghai in China.We investigated and analyzed the variation in phenotypic traits among and within these natural populations.The main results are as follows:(1)The analysis of 11 phenotypic traits showed that the coefficient of variation in secondary branch number was the largest,while that of grain length was the smallest.Among the examined populations,the coefficient of variation within the Boluo population was the largest.The analysis of variance suggested that all traits,except for the awn length,were significantly different among the eight populations.(2)The results of correlation analyses showed that there were different degrees of correlations between the traits,most of which were significantly or extremely significantly related.In particular,there was a very significant correlation between flag leaf length/width,grain number per panicle and branch number.Panicle length,grain number per panicle,and branch number.Plant height,primary branch number,panicle length,and grain number per panicle were significantly negatively correlated with latitude.(3)The results of phenotypic diversity index showed that the average diversity index of the primary branch number was the highest(1.772)and the index of the diversity of ear type was the lowest(0.691).The comparisons among the examined populations revealed that the phenotypic diversity index of the Qionghai population was the highest(1.563)(4)The analysis of principal components showed that the variation of flag leaf length/width,grain size,and ear characteristics played a major role in phenotypic variation among the studied populations.(5)The accurate and reliable phenotypic data will form solid foundation for subsequent genome-wide association analysis.The application of the phenotypic data to the subsequent genome-wide association analysis was discussed based on the obtained results.(6)The chloroplast genome of a common wild rice was assembled and annotated and we reconstructed the phylogenetic relationships of the genus Oryza.