Study On Genetic Diversity Of 29 Bromus Inermis Germplasm

The genetic diversity of 29 Bromus inermis germplasm were conducted with the phenotypic characteristics and ISSR markers.To explore the correlations and internal connections between phenotypes and molecular levels from the richness,morphological diversity and genetic characteristics of bromus indica germplasm resources,This study provides theoretical basis for further development,utilization,germplasm innovation and breeding of new varieties of bromeless brome germplasm resources.The results are as follows:(1)The different accessions exhibited various degree of diversity for these available 23 traits in which the variation of spikelet number was the largest with 32.92%.Principal component analysis showed that the cumulative proportion of former 6 principal components reached 77.92%with the Leaf type,spikelet,comprehensive,seeds,main stem,panicle as the first to six component.the 29 B.inermis germplasm were divided into 3 groups based on phenotypic traits.The group Ⅰ was tall plant,few spikelet,small leaves.The group Ⅱ was short plant,thin stem,light seeds.The group Ⅲ was big leaves,more spikelets,big seeds,weight seeds.The exotic germplasm introduced in this study has a certain practical significance on enriching the germplasm resources of China’s bromegrass and further carrying out the breeding of varieties.(2)A total of 273 ISSR polymorphic bands were amplified by screened 16 ISSR primer pairs and 29 Bromus inermis materials,The bands amplified by each primer range from 10(YW25)to 22(YW10).An average of 17.06 bands were amplified per primer pair,the total number of polymorphic sites was 253,the average number of polymorphic sites was 15.81,and the percentage of polymorphic sites reached 92.67%.The Nei’s gene diversity indices(H)ranged from 0.255 to 0.355,with the average of 0.310.(3)The genetic similarity coefficient(GS)of 29 Bromeless Brome germplasm materials ranged from 0.518-0.902,with an average of 0.649.The genetic distant(GD)ranged from 0.103-0.6532,with an average of 0.437.GS is the most between 0.6-0.7,accounting for 49%,and the overall distribution is mainly between 0.5-0.7,accounting for about 78%.GD is the mostt between 0.4-0.6,accounting for about 66%,and 86%between 0.4-0.8.(4)four groups resources were identified at 0.644,the cluster threshold,according to the cluster analysis based on ISSR molecular marker.Type 1 includes 10 Xinjiang germplasms and 1 Russian germplasm,Type 2 includes 5 Russian germplasms and Xinjiang,Ukraine,Kyrgyzstan,Portugal,Canada,and US germplasms,and Type 3 includes 2 Canada Germplasm and 4 Russian germplasms.There is only 1 material in the type 4,which comes from Russia.The results of principal component analysis are completely consistent with the cluster analysis.