Molecular Evidence for Progenitorial Species of Garden Petunias Using Polymerase Chain Reaction—Restriction Fragment Length Polymorphism Analysis of the Chs-j Gene

Abstract

Wild species and cultivars of Petunia were subjected to analysis for clarifying the historical progenitors of garden petunias (Petunia hybrida) using polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) of Chalcone synthase J (Chs-J) gene. The PCR products for Chs-J intron with adjacent part of exons digested with RsaI enzyme revealed that P. integrifolia and P. inflata (P. integrifolia complex), both with purple flowers, had one large-sized band [650 base pairs (bp)], whereas P. axillaris (P. axillaris complex), a white-flowered species, showed two smaller-sized bands (200 or 280 bp and 350 bp). In P. axillaris, two different band patterns were found among the three subspecies: 200 and 350 bp for P. axillaris subsp. axillaris and 280 and 350 bp for P. axillaris subsp. parodii and subsp. subandina. The 200-bp band was revealed to be specific to P. axillaris subsp. axillaris. P. hybrida cultivars showed four different band patterns, each of which consisted of two to three of the four bands (200, 280, 350, and 650 bp) detected in the wild taxa examined. These results indicate that the wild species analyzed here might partially have contributed to the Chs-J gene of garden petunias analyzed and demonstrate the use of PCR-RFLP in establishing relationships among closely related species and cultivars of Petunia. The puzzling problem related to the possible contribution of more than one subspecies of P. axillaris is discussed.