Genetic Analyses of Chinese <i>Cynodon</i> Accessions by Flow Cytometry and AFLP Markers

Abstract

Bermudagrass [ Cynodon dactylon (L.) Pers.] is widely distributed in China, but little information exists on genetic diversity within the germplasm pool. This study was conducted to assess variations in ploidy and amplified fragment length polymorphisms (AFLPs) among Cynodon accessions collected from 11 Chinese provinces. Flow cytometry and AFLP analyses were performed on 132 and 119 Chinese accessions, respectively. Four ploidy cytotypes were found among the Chinese accessions. Tetraploid (2 n = 4 x = 36) accessions were most prevalent (88%), with nuclear genome sizes ranging from 1.96 to 2.30 pg/2C nucleus −1 Seven hexaploid (2 n = 6 x = 54), three pentaploid (2 n = 5 x = 45), and six triploid (2 n = 3 x = 27) accessions had respective nuclear genome size of 2.90 to 3.13, 2.37 to 2.49, and 1.55 to 1.65 pg/2C nucleus −1 The accessions were grouped into five clusters based on 466 polymorphic AFLP bands. Genetic similarity coefficients (GSCs) of two clusters containing ‘Tifway’ and ‘Tifgreen’ ranged from 0.97 to 0.99, suggesting the triploid plants most probably were introduced cultivars from the USA. Within the Chinese indigenous accessions, GSC ranged from 0.65 to 0.99. Tetraploid genotypes had the greatest genetic variation with GSC ranging from 0.69 to 0.99, while pentaploids had the least with GSC ranging from 0.95 to 0.98. Genetic differentiation among the later three ploidy levels is evident. Fully sampling the genetic diversity of Cynodon in China will require more comprehensive collection throughout its distribution.