Study On Genetic Variation Of Apocynum Spp.and Poacynum Spp.Genotypes Using Agronomic Traits And DNA Barcodes

Apocynum spp.and Poacynum spp.are perennial herbaceous plants of genus Apocynum and Poacynum,which not only have good ecological characteristics of drought resistance,salt resistance,freezing resistance,high temperature resistance and wind sand resistance,but also have good medicinal value and textile value.However,the deterioration of ecological environment and the native germplasm resources of Apocynum spp.and Poacynum spp.were seriously damaged,which makes this germplasm increasingly rare.In this study,the genetic variation was analyzed among different genotypes of Apocynum spp.and Poacynum spp.by using agronomic traits and plant barcodes.The phylogenetic relationship of each genotype was also clarified.These results will provide a foundation for future breeding of new varieties?lines?with high yield and high quality,and provide a scientific basis for protection and rational development and utilization in Apocynum spp.and Poacynum spp.The main results are as follows:1.Eight genotypes of Apocynum spp.and Poacynum spp.were used to analyze seed morphological characteristics and viability test methods.The results showed that the seed length,width and height of eight genotypes ranged from 2.75 to 4.51mm,0.68to 0.90 mm,and 0.48 to 0.61 mm,respectively.Thousand seed weight ranged from 0.38to 1.32 g.All genotypes had brown seeds and vability ranged from 83.0%⁹7.5%.The suitable method for the determination of viability was cutting the seed coat vertically after a pre-wetting period of was 12-14 hours,then cut seeds were dyed for 12 h.The identification criteria is 80%staining of seed embryo.2.From 2017 to 2019,the yield traits,quality traits,and metal element content of eight genotypes of Apocynum spp.and Poacynum spp.were measured at the early flowering stage and the full flowering stage in Altay,Xinjiang and Yuzhong,Gansu,respectively.The results showed that the yield-related traits were significantly different between the genotypes at the early flowering stage and the full flowering stage?P<0.05?;The yield-related traits were significantly different by year and genotype interactions?P<0.05?,and location,year and genotype interactions?P<0.05??except for the traits of dry weight?.The Xinjiang site,the plant at the early flowering stage has relative higher plant height,number of branches,leaf dry weight and stem dry weight,with an average of 99.10 cm,5.52,26.41 g,25.35 g respectively.There were significant differences between the genotypes in the quality traits at the early flowering stage and the full flowering stage?P<0.05?;The range of crude protein and crude fat of each genotype at different locations at at the early flowering stage of different years were 8.64 to 10.07%,the average content of flavone was 2.31 mg/100g.There were significant differences in the content of Ca,Cu,Fe elements in various genotypes at at the early flowering stage in different years?P<0.05?.Principal component analysis found that the genotype of G₁in Xinjiang has a higher neutral detergent fiber and leaf dry weight,and the genotype of G₂ has a larger stem thickness,branch number,and stem-to-leaf ratio.3.Five DNA barcode sequences were selected to identify 9 different genotypes of Apocynum spp.and Poacynum spp.Among them,rbcL has the longest amplification length of 777 bp,ITS has the highest GC content of 61.05%,and the GC content varies from 34.78%to 61.05%.A total of 71 mutation sites were detected,and the number of mutation sites was in the range of 5-37.Among them,psbA-trnH sequence had the most mutation sites and rbcL had the least.The barcodes matK,rbcL and trnL-F could divide all genotypes into 2 groups,which can distinguish A.venetum cv.Ningxia and P.hendersonii,and red stem and little flower and A.venetum cv.Ningxia are grouped together.By using the combination sequence of matK+ITS and matK+psbA-trnH,Red stem and little flower can be clustered together with A.venetum cv.Ningxia,and other genotypes also can be distinguished.