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Wild Vigna [Vigna trinervia (Heyne ex Wall.) Y. Tateishi & N. Maxted]

Explanations

Taxonomy
Vigna trinervia is a perennial herb belonging to the subgenus Ceratotropis inthe genus Vigna. In the most widely accepted taxonomic treatment of Vigna proposed by Marechal et al. (1978), some specimens treated as V.radiata var.sublobata were recognized as distinct species, under the name of V.trinervia (Tateishi 1985). Judging from the RAPD analysis, V.trinervia is considered to be closely related to tetraploid species V.reflexo-pilosa and V.glabrescens (Tomooka et al. 1995).
Distribution
Madagascar, South India, Sri Lanka, Myanmar, Malaysia, Sumatra, Java, Timor, New Guinea (Tateishi, 1985).
Characteristics
According to Tateishi(1985), the morphological characteristics of V.trinervia is as follows. Stipules peltate, oblong, acute at the apex, 8-15mm long, 3-6.5mm wide. Terminal leaflet narrowly ovate to broadly ovate, or narrowly triangular-ovate to triangular ovate, rarely lanceolate, entire or sometimes faintly 3-lobed, acuminate or acute at the apex. Bracteoles lancxeolate to ovate or oblong, acuminate, 4.5-10mm long, distinctly longer than the calyx. Flowers golden yellow, 15-24mm in diameter. The pocket on the keel petal 3.5-6mm long. Pods spreading, linear, cylindrical, blackish brown when mature, 5-6cm long, 3-4mm wide, 10-14 seeded. Seeds short rectangular, truncate at both ends, somewhat transversly compressed, greyish brown. Hilum linear, 1.5-2mm long, aril thin, seed coat covering reticulate. Germination hypogeous, primary leaf cordate with long petiole. 2n=22.
As genetic resources
We have conducted 4 explorations and collected many seed samples of V.trinervia in the peninsular Malaysia (Bujang et al. 1994). The evaluation as a genetic resources, such as resistance against diseases and insects has not been carried out. Egawa et al. (1996) successfully develop vital F1 plants in the crosses between V.radiata var.sublobata x V.trinervia. There are no genebanks that have accessions of V.trinervia throughout the world. Therfore, collection and evaluation of this species is considered to be very important.
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., S.Chotechuen, N.Tomooka, S.Ngampongsai and C.Kitbamroong 1996. Cross-Compatibility among the Subgenus Ceratotropis Species of the Genus Vigna. In "Phylogenetic Differentiation of Mungbean Germplasm (Subgenus Ceratotropis of the Genus Vigna) and Evaluation for Breeding Program. Under the collaborative research program between JIRCAS(Japan) and DOA (Thailand) pp.19-30.
Marechal,R., J.M.Mascherpa and F.Stainer. 1978. Etude taxonomique d'un groupe complexe d'speces des genres Phaseolus et Vigna (Papilionaceae) sur la base de donnees morphologiques et polliniques, traitees par l'analyse informatique. Boissiera 28.
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., 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)