Analysis of Anthocyanin Components and Genetic Relationship of <I>Rhynchostylis gigantea</I> (Lindl.) Ridl. Flower

Abstract

Rhynchostylis gigantea is an epiphytic orchid commonly found in Thailand. Generally, there are four varieties of this species, pure white flower (R. gigantea var. harrisoniana), white with red-spots, white with red-blotches and solid red flower (R. gigantea var. rubrum). Recently, the new hybrid types having orange and pink-orange flowers have been developed. Thus, Anthocyanin pigment components of flower colors of this species are of interest to study. HPLC technique was used to identify pigments of R. gigantea flowers. Genetic variation of R. gigantea flowers was studied by RAPD technique using 20 random primers. It was found that primers OPF01, OPF04, OPF05, OPF06, OPF09, OPF12 and OPF14 were able to reveal genetic variation especially OPF01 and OPF06. The selected primers could classify R. gigantea varieties into 3 groups with relevance to flower color characteristics and anthocyanin derivatives. The first group was pure white flower which did not have anthocyanin derivative in flower. The next group having 78% genetic similarity was composed of white with red-spots and white with red-blotches flowers, the main components in flower colors were pelargonidin-3-O-glucoside, peonidin-3-O-glucoside, delphinidin and kuromanin. The last group was dark red and orange flowers with 65.6% genetic similarity contained kuromanin, pelargonidin-3-O-glucoside, peonidin-3-O-glucoside, delphinidin and cyanidin as main components in flower colors.