Analysis Of The Diversity Of Leaf And Fruit Saponin Content Of Sapindus And Screening Of High Quality Germplasm Resources

Sapindus mukorossi is a versatile deciduous tree resource of the genus Sapindus in the family Sapindaceae.Sapindus leaves and fruits are rich in triterpenes,sesquiterpenes and other saponins,which are important functional components of its natural washing and herbal resources and are closely related to the quality of Sapindus.Therefore,saponin content has become an important guide for the selection and breeding of excellent germplasm resources of Sapindus.However,at present,most of Sapindus is utilized and planted as wild resources and green forests(fallow forests and stone desertification management),and the saponin content is highly differentiated and the benefits are not significant.In this study,we collected 80 leaves and fruits of Sapindus from a resource collection bed for stone desertification management in Shimen County,Hunan Province,and determined the total saponin content using high performance liquid chromatography analyzer,and applied diversity analysis,correlation analysis,principal component analysis,and cluster analysis to comprehensively analyze the correlation between the phenotypic characteristics of leaves and fruits and the total saponin content,from which we selected Sapindus leaf and fruit resources with high saponin content in a preliminary screening,with a view to provide Sapindus resources.The results of this study are as follows.The main results of the study are as follows:(1)The leaf saponin content(3.28-9.06)and 20 leaf phenotypic traits in 80 Sapindus resources had different degrees of variation and association.The highest coefficients of variation were found in compound leaf width(coefficient of variation 29.8%),compound leaf area(coefficient of variation 27.4%),leaflet length(coefficient of variation 29.6%)and leaflet area(coefficient of variation 28.3%),and the most stable genetic variation was found in leaflet number(coefficient of variation 9.8%).The saponin content in leaves was significantly negatively correlated with compound leaf width and leaflet length,and the saponin content was higher in the narrower leaves.Based on principal components and cluster analysis,the leaf phenology and saponin content of Sapindus were divided into three taxa,and the average compound leaf length of 25.34 cm,compound leaf area of 444.31 cm2,leaflet area of 36.17 cm2,leaf saponin content of 5.06 μg/mL,and overall score of 0.20 of taxon Ⅱ were higher than the other two taxa.The five superior plants of Sapindus zw67,zw56,zw6,zw11 and zw57 with saponin-rich leaves were selected in the initial screening of taxon Ⅱ.(2)The fruit saponin content and fruit phenotypic traits of the 80 resources differed greatly.Among them,fruit skin thickness,fruit 100 grain weight and fruit transverse and longitudinal diameter were closely related to saponin content.The results of the principal component analysis showed that three principal components,namely,transverse diameter,100-grain weight and saponin content,explained 82.89%of the fruit traits of Sapindus.Based on the clustering analysis of saponin content and fruit phenotypic index,the 80 resources were also divided into three major groups,among which group I had the highest mean cross diameter of 25.68 mm,longitudinal diameter of 22.50 mm,lateral diameter of 22.01 mm,peel thickness of 3.77 mm,100 grain weight of 343.77 g,fruit saponin content of 9.75 μg/mL,and overall score of 0.66.They were the most suitable for breeding and screening as fruit-use saprophytes.We selected zw72,zw20,zw37,zw45 and zw38 from taxon Ⅰ as high quality Sapindus resources with high fruit saponin content.(3)Gray correlation analysis of leaf and fruit phenotypic traits and saponin content showed that several traits were highly correlated with leaf saponin content and fruit saponin content.The highest correlation(0.901)was found between fruit transverse diameter and leaf saponin content.Fruit lateral diameter had the highest correlation with fruit saponin content(0.888).Stepwise regression analysis showed that the 13 traits led by longitudinal diameter,pericarp thickness,and 100 grain weight represented 93.2%of the variation in the composite score F and could be used as characteristic traits of Sapindus.Cluster analysis showed that the resources with higher leaf and fruit saponin content had the following characteristics:shorter plant shape,longer compound leaves and leaflets attached to compound leaves,larger fruits,and higher fruit yield,among which five excellent resources with higher leaf and fruit saponin content were selected.zw38,zw45,zw61,zw37,and zw76 were selected.In summary,the 80 Sapindus resources had different degrees of genetic variation in plant shape,leaf and fruit phenotypic traits and saponin content.The leaf and fruit phenotypic traits were correlated with the saponin content,and the screening indexes of high saponin content in leaf and fruit peel resources were selected,in which the saponin content in leaf was significantly negatively correlated with the compound leaf width and leaflet length;the fruit cross diameter,fruit peel thickness and 100 grain weight were positively correlated with the saponin content in fruit peel;the height under branch,leaf length,fruit cross diameter and 100 grain weight were closely correlated with the saponin content in leaf and fruit.