Search

A total of 148 accessions representing six important species of the genus Stylosanthes, including S. guianensis, S. hamata, S. scabra, S. seabrana, S. macrocephala, and S. capitata, were used to evaluate genetic variation and relationships using sequence-related amplified polymorphism markers. The results showed that the 18 selected primer pairs generated 138 distinct fragments. The fragment sizes ranged from 150 to 2000 bp. Genetic similarity coefficients among the 148 accessions ranged from 0.51 to 0.99, with an average of 0.79. The effective allele number (ne) generated by the 18 primer pairs averaged 1.3552 and ranged from 1.2069 to 1.6080; Nei’s gene diversity (He) ranged from 0.1304 to 0.3207, with an average of 0.2070; and Shannon’s information index (I) averaged 0.3213 and ranged from 0.2233 to 0.4582. The unweighted pair-group method with arithmetic averages at the 0.69 similarity level separated the 148 accessions into two distinct groups. One group belonged to S. guianensis, and the other group belonged to the non-S. guianensis type. This study verified that Stylosanthes have rich genetic variation, which is an excellent basis for Stylosanthes breeding for new cultivars. This study demonstrates that the SRAP technique is a reliable tool for differentiating Stylosanthes accessions and for discerning genetic relationship among them.

The objectives of this research are to reveal the genetic variation and relationships of 29 Cynodon arcuatus accessions from different regions of China using inter-simple sequence repeat (ISSR) markers and sequence-related amplified polymorphism (SRAP) markers, and to assess the levels of polymorphisms detected by the 2 different markers and compare their efficiencies. The markers were used to provide essential information for the exploration and utilization of C. arcuatus germplasms. A total of 189 bands from 300 bp to 3000 bp were amplified by 14 ISSR primers, while 334 bands from 260 bp to 1800 bp were observed by 15 SRAP primer combinations, of which 187 (98.94%) and 316 (94.61%) were polymorphic, respectively. The ranges of genetic similarity coefficients (GSC) were 0.45–0.90 for ISSR markers, 0.48–0.94 for SRAP markers, and 0.48–0.90 for ISSR + SRAP markers. Cluster analysis using 2 methods, specifically the unweighted pair-group method with arithmetic averages and principle coordinate analysis, showed that the C. radiatus accessions clustered into 5 distinct groups using ISSR markers, 6 groups using SRAP markers, and 5 groups using ISSR + SRAP markers. The present study verified that C. arcuatus has rich genetic diversity in Hainan with the use of ISSR and SRAP markers, which provided basis for molecular breeding and germplasm creation of C. arcuatus. This study showed that the combination of both methods would be a very good way for the analysis of Cynodon accessions, which would be a good experience for further studies of the diversed Cynodon genus.

Genetic variation in 55 accessions of Cynodon dactylon was estimated using inter-simple sequence repeat (ISSR) markers. The plant materials used in this study originated from 17 countries. A total of 236 ISSR fragments were generated with 14 primers. Fragment sizes ranged from 200 to 3000 bp. All scorable bands were polymorphic in nature and none of the primers used produced monomorphic bands, indicating a high level of genetic variation in this grass. The accessions were found to be clustered into eight major groups through the unweighted pair-group method with arithmetic averages. Genetic similarity coefficients (GSC) among the 55 accessions ranged from 0.52 to 0.95. The results clearly indicate that a high level of variation exists in Cynodon accessions. This study shows that the ISSR technique is a reliable tool for differentiating Cynodon accessions and for determining the genetic relationships among them.

Although Cynodon dactylon (C. dactylon) is widely distributed in China, information on its genetic diversity within the germplasm pool is limited. The objective of this study was to reveal the genetic variation and relationships of 430 C. dactylon accessions collected from 22 Chinese provinces using sequence-related amplified polymorphism (SRAP) markers. Fifteen primer pairs were used to amplify specific C. dactylon genomic sequences. A total of 481 SRAP fragments were generated, with fragment sizes ranging from 260–1800 base pairs (bp). Genetic similarity coefficients (GSC) among the 430 accessions averaged 0.72 and ranged from 0.53–0.96. Cluster analysis conducted by two methods, namely the unweighted pair-group method with arithmetic averages (UPGMA) and principle coordinate analysis (PCoA), separated the accessions into eight distinct groups. Our findings verify that Chinese C. dactylon germplasms have rich genetic diversity, which is an excellent basis for C. dactylon breeding for new cultivars.