Study On Genetic Diversity Of Leymus Chinensis Germplasm Resources

Leymus chinensis(Trin.)Tzvel.is a perennial,rhizomatous plant of the Leymus within the Gramineae family,with good palatability and high nutritional value,and is a high-quality forage resource.L.chinensis also has a wide range of adaptability and tolerates the damage caused by cold,drought,barren and saline-alkali,is an excellent ecological grass resource in China.This study addresses the problem of insufficient innovation and utilization of L.chinensis germplasm resources,low efficiency and slow progress in breeding excellent cultivated new varieties of L.chinensis,resulting in the current situation of high-quality L.chinensis forage shortage livestock industry and serious shortage of excellent grass seed sources in grassland ecological construction.In this study,taking 92 L.chinensis germplasm resources introduced and collected as the research materials,through the evaluation and analysis of 12 phenotypic traits genetic variation,correlation,principal components,clustering and genetic parameters of 28 L.chinensis germplasm materials,and the molecular level genetic diversity of 92 L.chinensis germplasm materials,genetic relationships and cluster analysis,explore the genetic diversity and analyze their genetic structure,and then screen resources with breeding potential,and discover high-yield and high-quality germplasm materials with excellent genetic characteristics and high genetic potential.The theoretical basis and excellent breeding materials were provided for the creation and utilization of L.chinensis germplasm resources as well as improving the efficiency and accelerating the breeding process of L.chinensis.The main results as follows:1.The analysis of the variation coefficient and the diversity index of 28 L.chinensis resources for 12 phenotypic traits showed that the dry weight,fresh weight and leaf width of L.chinensis all ranked first,while the traits of seed length and seed width ranked last.Therefore,excellent traits can be selected in the population for new germplasm creation.2.The correlation analysis of phenotypic traits showed that plant height(vegetative plant height and reproductive plant height),leaves,and spikes were significantly correlated with L.chinensis yield(fresh weight per plant and dry weight per plant),but not with seed morphology.The main factors affecting seed traits were spike length and spikelet number;the spike traits were mainly affected by the number of spikelet and yield;the main traits that affect leaf traits are stem diameter,spike and yield;the traits that affect plant height are mainly leaf,spike and yield.When different traits are used as breeding objectives,the interaction between traits should be considered.3.The principal component analysis identified four main trait components,and based on the principal component comprehensive score and clustering results,eight germplasm resources were selected with good breeding potential and outstanding comprehensive trait performance,including 67,60,57,69,91,63,92 and 88,respectively.4.Through the analysis of phenotypic variation and genetic variation coefficient,the genetic variation coefficient and phenotypic variation coefficient of fresh weight,dry weight,and seed width traits of 28 L.chinensis germplasm materials were relatively high,indicating that there were relatively more types of variation in these three traits,and a wide range of options were available in breeding,making it easier to achieve breeding goals through hybridization and selection.5.The analysis of genetic parameters showed that among the genetic progress of various traits,plant height had the highest genetic progress,while seed morphology(seed length and seed width)had the lowest genetic progress.The relative genetic progress of yield traits is the highest,and the seed length is the lowest among all traits.6.The genetic diversity of ISSR was studied on 92 germplasm resources of L.chinensis using 17 primers,and a total of 165 loci were amplified,140 polymorphic loci,and the polymorphic locus ratio was 84.85%.The observed allele number(Na)of L.chinensis germplasm was 1.9333,the effective allele number(Ne)was 1.6692,the Nei′s gene diversity index(H)was 0.3684,and the Shannon′s information index(I)was 0.5341,which was rich in genetic diversity.The cluster analysis divided the L.chinensis germplasm into 7 groups,and the research results will provide a reference basis for the development and utilization of L.chinensis germplasm resources.