SSR Analysis of Inheritance Mode in Cynodon dactylon var. dactylon (L.) Pers.

Common bermudagrass [C. dactylon var. dactylon (L.) Pers.] is the most popular and economically important member among Cynodon species because of its wide and multiple uses for turf, forage and soil erosion control in the world. While an array of ploidy forms from diploid (2n=2x=18) to hexaploid (2n=6x=54) has been reported in the taxon, the major ploidy of common bermudagrass is tetraploid (2n=4x=36). However, information regarding the inheritance of common bermudagrass chromosomes is limited. Accordingly, this experiment was designed to investigate the inheritance mode (disomic, tetrasomic or intermediate) in common bermudagrass. Initially, 228 S1 (first self-generation) inbreds of ‘Zebra’ bermudagrass (2n=4x=36) were genotyped with 21 simple sequence repeat (SSR) markers. Among them, segregation of two markers was consistent with a 1:2:1 ratio, and one SSR amplified two bands (AB and BB) which exhibited a 1:3 segregation ratio. Serious segregation distortion of other 18 markers from either disomic or tetrasomic inheritance was observed.  Second S1 population of 273 genotypes derived from a parent #118 was genotyped with 10 SSR markers. Segregation of eight SSRs was in agreement with Mendel’s segregation ratio of “1:2:1 (χ², P>0.01), and other two markers were distorted from the ratio. Collectively, SSR inheritance of the two common tetraploid bermudagrass populations was disomic.