The Optimization Of DUS Test System And Identification Of Varieties Based On RAD-seq In Lolium Multiflorum

Italian ryegrass is(Lolium multiflorum Lam.)a kind of annual cold season high quality forage,which is mainly used as winter fallow field forage in the south of China.Sowing in the middle and late ten days of October,the growth is rapid,the protein content is high,and the palatability is good.The introduction of Italian ryegrass in China was relatively late,and related researches also started relatively late.As one of the major herbage in China and one of the important grass species in the development of grass husbandry,it is indispensable to select high-yielding and high-quality Italian ryegrass varieties.In the process of breed selection,it is a crucial step to distinguish and identify of new varieties(lines)is a crucial step.Therefore,this experiment measured the quantitative characters of 7 standard varieties of Italian ryegrass introduced from Japan for DUS test,screened the consistency within the variety population and the quantitative characters with better specific expression between populations for grading analysis,which was used to identify and describe 8 varieties and optimize the DUS test system of Italian ryegrass.At the same time,based on RAD simplified genome sequencing technology,this experiment determined the SNP markers within the genome range of 11 national Italian ryegrass,The genetic differences among varieties revealed by the differences in the number of SNP markers were used to identify the varieties.The main experimental results are as follows:1、DUS test system optimization of Italian ryegrass.In this experiment,18 quantitative characters of 7 standard varieties of Italian ryegrass introduced from Japan were measured firstly,The results show that,when analyzing the consistency of varieties,the six characters of leaf color degree,growth habit after vernalization,plant width at booting stage,flag leaf width at booting stage,flag leaf length width ratio at booting stage and outer spikelet length did not perform well in the internal consistency of several varieties,the plant height at booting stage,the ratio of length to width of flag leaf at booting stage,and the differences among populations with spikelet density were poor.K-s test andχ~2 test are carried out for the 10 quantitative traits,only the basal spikelet length belonged to the 2 test.Finally,the 10 quantitative traits are divided into 5 grades.The tested varieties and new lines of multiflorum ryegrass were identified.According to the results of classification,they can be completely clusters,which correspond to the varieties into 8 groups,which corresponding to each other,and the differences between the 8 varieties and new lines of Italian ryegrass were distinguished,which provides a reference for the DUS test guide of Italian ryegrass.2、Identification and population genetic analysis of 11 Italian ryegrass species in China based on RAD simplified genome sequencingIn this study,11 national Italian ryegrass cultivars were selected as the research objects.A total of 18558247 SNP sites were detected by RAD simplified genome sequencing technology,the average SNP number of different varieties of Italian ryegrass is different.In the meantime,principal component analysis,phylogenetic analysis,genetic differentiation analysis,genetic structure analysis and other methods are used to analyze the number differences of SNPS among different varieties.The results of these analyses can intuitively show the differences and genetic diversity among 11 Italian ryegrass varieties.It is verified that RAD simplified genome sequencing can provide guidance for the identification of Italian ryegrass varieties.