Phylogenetic relationships of turfgrasses as revealed by restriction fragment analysis of chloroplast DNA

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Chloroplast DNAs (cpDNAs) were analyzed in order to clarify the phylogenetic relationships among turfgrasses. Physical maps of cpDNAs from Agrostis stolonifera and Zoysia japonica, which are representative species of cool (C3 type) and warm (C4 type) season turfgrasses, respectively, were constructed with four restriction enzymes, i.e., PstI, SalI, SacI, and XhoI. The genome structures of these cpDNAs were found to be similar to each other in terms of genome size and gene orders, showing thereby a similarity to other grass cpDNAs. CpDNAs of 5 species of cool season turfgrasses and 6 species of warm season turfgrasses as well as four species of cereals, distributed among 14 genera of Gramineae, were digested with PstI, XhoI, and BamHI, and their restriction fragment patterns were compared. Their genome sizes were estimated to be 135-140 kbp. Each species showed characteristic RFLP patterns. On the basis of the frequency of commonly shared fragments, a dendrogram showing the phylogenetic relationships among their cpDNAs was constructed. This dendrogram shows that turfgrasses can be divided into three major groups; these correspond to the subfamilies. Cool and warm season turfgrasses are clearly distinguishable from each other, and the latter can be further classified into two subgroups that correspond to Eragrostoideae and Panicoideae. Our classification of turfgrasses and cereals by RFLP analysis of cpDNA agreed in principal with their conventional taxonomy, except for the location of Festuca and Lolium.