Genetic Diversity And Screening Of Excellent Salt-tolerant Germplasm Resources Of Paspalum Vaginatum Accessions

Paspalum vaginatum is a warm-season perennial grass of the Gramineae family,growing by the seaside.It has many excellent resistances to abiotic stresses,such as salinity,cadmium and drought.However,the research on genetic diversity and salt stress of local resources in China is few reported.In this study,morphological markers and SSR markers were used to analyze the genetic diversity of Paspalum vaginatum accessions at home and abroad,and the salt stress of these resources was evaluated to study the relationship between salt stress and the concentration of Na~+,K~+,and to understand the mechanism of ion regulation of P.vaginatum under salt stress.It provides important theoretical basis for further development and utilization of P.vaginatum accessions.The main contents of this study are as follows:1.Study on morphological diversity of P.vaginatumNine morphological indexes were used to analyze the morphological diversity of97 P.vaginatum accessions.The results showed that the morphological variability of the germplasm resources was greater,and the coefficient of variation was more than20%.The largest variation was turf height(69.38%),and the smallest was turf quality(23.91%),with an average of 39.16%.The correlation between all of the morphological indexes was very significant(P<0.01),indicating that there was a high correlation among the indexes.2.Genetic diversity analysis of SSR molecular markers in P.vaginatum accessionsA total of 27 pairs primers of clear and obvious bands were screened out by 63pairs of SSR primers.Among them,22 pairs of primers are polymorphic,and 57alleles were amplified by amplification from 144 P.vaginatum accessions.2 to 4alleles were detected per primer,with an average of 2.6 alleles.The genetic variation of the genetic diversity of P.vaginatum was analyzed.It was showed that primer ESSR3 had the highest observed heterozygosity(Ho),expected heterozygosity(He),and PIC,indicating that primer ESSR3 had higher polymorphism.The results of cluster and principal component analysis classified P.vaginatum accessions into 4groups.3.Study on salt stress of Paspalum vaginatum accessionsThree Paspalum vaginatum materials were screened for salt tolerance by setting seven Na Cl concentration gradients(0,5,10,15,20,25,30 g/L).According to the results of salt tolerance index,25g/L Na Cl was finally selected for salt tolerance evaluation.Using leaf firing percentage,turf quality,dry shoot weight and dry root weight as the measurement indexes,the salt stress of 99 Paspalum vaginatum accessions was evaluated,and the results showed that the coefficient of variation of leaf firing percentage,turf quality,relative dry shoot weight and relative dry root weight were all more than 20%,which indicated that there were rich genetic differences among Paspalum vaginatum accessions.Then,combining the salt tolerance index with the turf quality of the field,the excellent salt tolerance germplasms were USA17-17 and USA17-18.The contents of Na~+and K~+in 62Paspalum vaginatum accessions under salt stress were measured.It was found that the concentration of Na~+increased above and below ground after salt stress,but the K~+and K/Na decreased.According to the correlation analysis between salt tolerance indexes and ion contents,it is concluded that maintaining higher K~+content and higher underground K/Na may be the ion regulation mechanism of salt tolerance in Paspalum vaginatum.