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Wild Vigna [Vigna reflexo-pilosa Hayata]

Explanations

Taxonomy
Vigna reflexo-pilosa is a wild legume belonging to the subgenus Ceratotropis in the genus Vigna. It is a tetraploid species which is considered to be an amphidiploid (Egawa et al. 1990).
Another tetraploid species, Vigna glabrescens is also described in the subgenus Ceratotropis (Marechal et al. 1978). On the other hand, Tateishi (1985) considered that V.glabrescens is a cultivated form of V.reflexo-pilosa and treated as subspecies of V.reflexo-pilosa, subsp. glabra.
We have examined the relationship between these two tetraploid species. V.reflexo-pilosa is cross compatible with V.glabrescens. They readily produced fertile hybrids when crossed with each other (Tomooka et al. 1991). Judging from the morphological similarities, the same ploidy level (2n=44, 4x), high level of hybrid fertility between them, the same profile of the electrophoregram of some isozymes and total seed protein (Tomooka et al. 1992, Egawa and Tomooka. 1994) and RAPD analysis (Tomooka et al.1995), we considered that V.reflexo-pilosa is the wild progenitor of cultivated V.glabrescens (Egawa and Tomooka 1994). 2n=4x=44.
Distribution
Ryukyu islands(the southernmost islands in Japan), Taiwan, South China (Hainan), Thailand, Philippines, Malaysia, Sumatra, Java, Timor, Australia, New Guinea, New Caledonia, New Hebrides and Fiji (Tateishi. 1985)
Characteristics
Flower color is golden yellow. The pocket on the keel is longer than that of mungbean. The seed testa is smooth with dark gray color. Seed size is 3.1-3.3 x 2.3-1.6mm. 100 seed weight is 1.4-1.7g. pod is 5-7.5cm long, containing 10 to 15 seeds. Germination is hypogeal.
As genetic resources
Since V.glabrescens showed very high level of resistance to insects and diseases (Fernandez and Shanmugasundaram, 1988), V.reflexo-pilosa (wild progenitor) will also harbor high level of resistance. Therefore, several explorations were conducted in the Nansei Archipelago, Japan (Egawa et al.1990, 1991, Tomooka et al.1992) and in Peninsular Malaysia seeking this species (Bujang et al. 1994). Tomooka et al.(1992) revealed a high level of resistance of V.reflexo-pilosa against a bruchid beetle (Callosobruchus chinensis).
References
Bujang,I., Y.Egawa, N.Tomooka, S.G.Tan, H.A.Abu Bakar and S.Anthonysamy, 1994. Exploration, collection and electrophoretic variants of wild Vigna (subgenus Ceratotropis) in Peninsular Malaysia. In Proceedings of the 3rd. Symposium of Applied Biology, pp.69-71.
Egawa,Y. and N.Tomooka 1994. Phylogenetic Differentiation of Vigna Species in Asia. JIRCAS International Symposium Series 2 : 112-120.
Egawa,Y., D.Siriwardhane, N.Tomooka, K.Tomita and H.Nakano, 1990. Collection of V.riukiuensis and V.reflexo-pilosa, wild relatives of azuki bean on Iriomote island, Okinawa prefecture. In "Natl. Inst. Agrobiological Resources (ed.) Annual Report on Exploration and Introduction of Plant Genetic Resources" Vol.6:23-30.
Egawa,Y., H.Horikoshi, N.Tomooka, and H.Nakano, 1991. Collection of wild relatives of adzuki bean, Vigna riukiuensis and V.reflexo-pilosa, on Yonaguni island, Okinawa prefecture. In "Natl. Inst. Agrobiological Resources (ed.) Annual Report on Exploration and Introduction of Plant Genetic Resources" Vol.7:13-20.
Fernandez,G.C.J. and S.Shanmugasundaram. 1988. The AVRDC Mungbean Improvement Program: The Past, Present and Future. In "Mungbean", Proc. 2nd Int. Symp. AVRDC. Shanhua, Taiwan. pp.58-70.
Tateishi,Y. 1984. Contributions to the Genus Vigna (Leguminosae) in Taiwan I. Sci.Rep. Tohoku Univ. 4th ser. (Biology) 38: 335-350.
Tateishi,Y. 1985. A revision of the Azuki bean group, the subgenus Ceratotropis of the genus Vigna (Leguminosae). Ph.D. Thesis, Tohoku University, Sendai, Japan.
Tomooka,N., C.Lairungreang, P.Nakeeraks Y.Egawa and C.Thavarasook. 1991. Mungbean and The Genetic Resources, The Subgenus Ceratotropis. Tropical Agriculture Research Center, Japan.
Tomooka,N., E.Penaloza, A.D.Vina and Y.Egawa. 1992. Variation of isozymes (SDH and Lap) and seed total protein in wild relatives of azuki bean, VIgna riukiuensis and V. reflexo-pilosa collected in the Nansei Archipelago, Japan. Breeding Sci.42 (Extra Issue 2):568-569. (in Japanese)
Tomooka,N., Y.Egawa, C.Lairungreang and C.Thavarasook, 1992. Collection of wild Ceratotropis species on the Nansei Archipelago, Japan and evaluation of bruchid resistance. JARQ, 26:3, 222-230.
Tomooka,N., V.A.Sumanasinghe, A.Kaga and Y.Egawa. 1995. Molecular taxonomic relationship among azuki group species in the genus Vigna based on RAPD analysis. Breeding Science Vol.45 (Extra issue 1):181. (in Japanese)
Verdcourt,B. 1970. Studies in the Leguminosae - Papilionoideae for the "Flora of Tropical East Africa" : IV. Kew Bulletin 24 : pp.558-560.