Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/25/2005
Publication Date: 2/24/2006
Citation: Wu, Y., Taliaferro, C., Bai, G., Martin, D., Anderson, J., Anderson, M., Edwards, R. 2006. Genetic analyses of chinese cynodon accessions by flow cytometry and aflp markers. Crop Science 46:917-926 Interpretive Summary: Grasses belonging to the genus cynodon dactylon (L.) Pers. are widely distributed in China but little is known about their genetic diversity. A total of 132 accessions were collected from 11 provinces in China and investigated using cytogentics and AFLP marker techniques. Cytogentics research revealed four types of cytotypes. The majority of accessions were tetraploid (88%), and others were hexaploid (7 accessions), pentaploid (3 accessions) and triploid (6 accessions). Based on molecular marker data, the accessions were grouped into five groups. According to results from cluster analysis, triploid plants were most likely introduced cultivars from the USA. Within the Chinese indigenous accessions, tetraploid genotypes had the greatest genetic variation, while pentaploids had the least. 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.
Technical Abstract: 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 (AFLP) among Cynodon accessions collected from eleven 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 (2n=4x=36) accessions were most prevalent (88%) with nuclear genome sizes ranging from 1.96 to 2.30 pg / 2C nucleus. Seven hexaploid (2n=6x=54), three pentaploid (2n=5x=45) and six triploid (2n=3x=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. Based on 466 polymorphic AFLP bands, the accessions were grouped into five clusters. Genetic similarity coefficients (GSC) 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 US. Within the Chinese indigenous accessions, GSC ranged from 0.65 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.