DNA analysis of the interspecific hybrid clones and the horticultural varieties of Chamaecyparis obtusa and C. pisifera

RAPD (random amplified polymorphic DNA) and SSCP (single strand conformation polymorphism) analyses were carried out to investigate the nuclear genome composition and chloroplast genome type of a natural hybrid and five horticultural varieties. In RAPD analysis, Fuji-2, a plus tree clone that is a natural hybrid between C. obtusa (SIEB. et ZUCC.) Endlicher and C. pisifera (SIEB. et ZUCC.) Endlicher, possessed all species-specific bands that were detected in these two species. It was reconfirmed at the DNA molecular level that this clone was an interspecific hybrid between them. SSCP analysis revealed that the chloroplast genome of Fuji-2 was C. obtusa type. This suggested that Fuji-2 was bred by crossing between C. pisifera as the seed parent and C. obtusa as the pollen parent. As no hybrids have ever been bred in this combination (C. pisifera × C. obtusa), a new possibility was shown in cross breeding of Chamaecyparis. In RAPD and SSCP analyses of horticultural varieties, each variety possessed species-specific bands of either C. obtusa or C. pisifera. The fact supported that they were mutants of C. obtusa or C. pisifera. From these results, DNA molecular markers such as RAPD and SSCP seem useful to identify the parental species of interspecific hybrid, and also useful to ascertain the origin of mutant.