Genetic diversity of chloroplast DNA in Zoysia and other warm-season turfgrasses

Although information on chloroplast genomes has been available and used for phylogenetic analysis in some Poaceae species, they are limited in warm-season turfgrass species including Zoysia. Twenty-four chloroplast DNA (cpDNA) regions of Zoysia japonica cultivar Asagake were amplified using primer pairs designed from the complete chloroplast genome sequences of Oryza sativa and Zea mays. The nucleotide sequences of each fragment ranged 330-1230 bp in length, with a total of 16 780 bp. Of the 24 cpDNA regions, six amplified regions -trnK intron (matK), intergenic region of trnD-psbM, atpA-rps14, petE-psaJ, atpB-rbcL and rps3-rps12 - were polymorphic among seven turfgrass species. The nucleotide sequences of these regions were used for the phylogenetic clustering of seven turfgrasses and two cereal crops. The phylogenetic tree showed that these nine genera segregated into three major groups corresponding to the four grass subfamilies, suggesting that the diversity of nucleotide sequences in these six cpDNA regions could be useful for assessing the phylogenetic relationships among turfgrass species. Chloroplast microsatellite markers were developed using nucleotide sequences of the amplification products with the 24 primer pairs from Z. japonica cultivar Asagake. Based on this 16 780-bp nucleotide sequence, 21 chloroplast microsatellites were developed from 18 regions. Ten of the 21 primer pairs exhibited polymorphisms among three species of Zoysia. These informative markers should be valuable tools in the study of genetic relationships across Zoysia species.