Morphology and molecular identification of Paphiopedilum Orchids

Abstract

Morphology and flowering period of 50 Paphiopedilum species representing 7 subgenera and 1 section were identified. Each group had unique character attribution among subgenera as follows. Brachypetalum had mottled green leaf color, single flower and rounded-elliptic petal. Cochlopetalum had green leaf color, gradually bloom one flower a month, short petal and twist and flowering all of the year. Paphiopedilum had green leaf color, single flower and petal with oblong shape. Parvisepalum had mottled green leaf color, single flower, rounded-elliptic petal, lip ovate to large rounded. Polyantha had green leaf color, inflorescence flower, linear long petal and twist. Sigmatopetalum had mottled green leaf color, single flower, petal with oblong shape and wide dorsal sepal. Megastaminodium had small plant size with mottled green leaf color, single flower, wide and flat staminode, linear petal and twist. Laosianum had small plant size with mottled green leaf color, single flower, very large flower size when compared with plant size and light purple color at petal with oblong shape. Flowering study showed that flowering periods of each species were different during the year. Genetic relationship study by random amplified polymorphic DNA (RAPD) could divide 19 Paphiopedilum species into 2 main groups and 6 subgroups of Brachypetalum, Paphiopedilum, arbata,cptaum,Ps oytha with similarity coefficients ranging from 0.20 to 0.84. The dendrogram revealed close relationship between P. appletonianum and P. callosum with similarity coefficient of 0.84. Distant relationship was found between P. concolor and P. philippinense with similarity coefficient of 0.20. Paphiopedilum myanmaricum was a species in subgenus Brachypetalum discovered in 2017. Leaf and flower characters were very similar to P. josianae. RAPD results showed that 11 Paphiopedilum species in subgenus Brachypetalum could be divided into 2 clusters of 4 subgroups with similarity coefficients ranging from 0.400 to 0.850. Genetic variation was in accordance with flower characteristics of each species. Dendrogram analysis revealed close relationship between P. concolor and P. concolor var. hennisianum with the highest similarity coefficient of 0.850 and between P. myanmaricum and P. josianae with similarity coefficient of 0.663. Chromosome study of P. myanmaricum by Feulgen squash method identified chromosome number 2n=26. Genetic analysis by amplified fragment length polymorphism (AFLP) could divide 50 Paphiopedilum species into 8 groups which were 1. Brachypetalum, 2. Cochlopetalum, 3. Parvisepalum, 4. Polyantha, 5. Sigmatopetalum, 6. Paphiopedilum, 7. Laosianum, and 8. Megastaminodium. P. jackii and P. malipoense had the closest genetic relationship with similarity coefficient of 0.924 while P. canhii and P. rungsuriyanum had the lowest genetic relationship with similarity coefficient of 0.373. P. sp. Lampang was included in a group of subgenus Paphiopedilum which was in accordance with its morphological information. When considered among 11 Paphiopedilum species in subgenus Paphiopedilum, P. sp. Lampang and P. charlesworthii were placed into different groups. These 2 species had similar flower but different staminode characters. P. sp. Lampang was categorized by AFLP into the same group with P. coccineum and P. sulivongii. Flower of P. sp. Lampang was closely related to but still distinct from that of P. coccineum. The results of morphological and AFLP analyses supported that P. sp. Lampang was a new species in the genus Paphiopedilum.