Analysis Of Genetic Diversity And Genetic Relationship For Weedy Rice From Ningxia

Rice is the main crop,more than half the world’s population live on this.However,in recent years,with the expansion of direct seeding rice fieldacreage,weedy rice damage worse,seriously threatening rice production.The source,propagation and genetic characteristics of weedy rice in Ningxia has not undergone systematic research,most rely on experience to judge and identify, bring certain difficulty to identify and control accurately.The weedy rice is harmful to the yield and quality of rice,but it can also be used in other.Therefore,the active collection of weedy rice resources,in-depth study of the genetic characteristics,living habits,and explore the origin and propagation of weedy rice,to the prevention,identificationand utilization of weedy rice in the future is important.In this study,the main agronomic traits of rice germplasm including weedy rices,improved cultivars and rice landraces,which were from Ningxia province,were evaluated.Using a total of 24 SSR markers distributed on 12 chromosomes,the genetic diversity,genetic similarity and clust-er analysis of different rice germplasm from Ningxia and the genetic diversity and genetic relati onship of weedy rice,improved varieties,landraces,wild rice from different geographic originswere conducted.The obtained results wereas follows:(1)The comparative analysis about phenotypic traits of weedy rice,improved varieties and Ian-draces in Ningxia was conducted.The results showed that the average diversity index of weedy rice(1.95)is higher than landraces(1.75),but slightly lower than improved varieties(1.98).In weedy rice group,average diversity index of 8 groups of weedy rice are near.The result of genetic diversity of weedy rice,improved varieties and landraces showed that Nei’s genetic diversity index of weedy rice was 0.4402,slightly less than improved varieties(0.4647),but there were no significant difference;Nei’s genetic diversity index of landraces was 0.2827,significantly lower than that of weedy rice and improved varieties.In weedy rice group,most of genetic diversity indexs were not significant difference.The result means that genetic diversities of weedy rice and improved varieties in Ningxia are similar,which is associated with single ecological type in Ningxia and evolution of weedy rice,and in weedy rice group there is no obvious regional differentiation.(2)The cluster analysis of weedy rice,improved varieties and landraces in Ningxia,according to phenotypic data was conduceted.Weedy rice,improved varieties,landraces are divided into 2 categories,group I contained improved varieties,group II included 8 groups of weedy rice and landraces.The cluster analysis according to SSR data was analyzed.The result showed that group I contained improved varieties,8 groups of weedy rice and landraces were sorted into group II and group III.In group II,there is no obvious boundaries in distribution among weedy rice population in Ningxia,this showed there is no obvious regional in the weedy rice.And it showed that rice germplasms between weedy rice and landrace in Ningxia were distributed uniformly,this means weedy rice with landrace are high degree of integration.Visible,the phyloge-netic relationship between weedy rice and landrace of Ningxia closer,the source of weedy rice were related to landrace.(3)Nei’s gene diversity index of 5 groups of weedy rice were analyzed,which are from different geographical origins.In 5 groups of weedy rice,the order of Nei’s gene diversity index is weedy rice in Jilin(0.5133),weedy rice in Ningxia(0.5022),weedy rice in Heilongjiang(0.4667), weedy rice in Korea(0.3767),weedy rice in Liaoning(0.3366).This suggested that there were differences in genetic diversity of weedy rice from different regions.Compared with wild rice, genetic diversity of weedy rice was lower than that of wild rice.(4)The cluster analysis of rice germplasm from different geographical origins showed that weedy rice populations were closely related to landrace from the same area but distantly related to improved variety from the same area and O.rufipongon.The genetic relationship between weedy rice in Ningxia,weedy rice in Heilongjiang,weedy rice in Jilin,weedy rice in Liaoning and japonica rice is closer,while the relationship between weedy rice in Korea and indica rice in Shaanxi is near,so the type of weedy rice is various,and there is indica-japonica differentiation in weedy rice populations.These results suggest that in this study most weedy rice is mostly likely involved from the local varieties,but the possibility of weedy rice formed from hybridization of indica rice and japonica rice,hybridization of cultivated varieties and wild rice,or directly formed from wild rice is low.There are some differences between weedy rice in different regions,it has regional,and the type of weedy rice is various,differentiation is more,the occurrence of weedy rice relatively independent,which may be the origin of the dispersion.