PLANT-REGENERATION INVITRO FROM PRIMARY LEAF NODES OF SOYBEAN (GLYCINE-MAX) SEEDLINGS

A simple and reproducible protocol for regeneration of soybean plants from explants derived from 7-day-old seedlings has been developed.Explants, each consisting of the primary leaf node (the unifoliate leaf node), the cotyledonary node, the internode between them, and one cotyledon, were cultured in vitro on a modified Murashige and Skoog (MS) agar medium containing 3% sucrose, four times the MS inorganic micronutrient level, the vitamins of B 5 medium, 2g L-1 L-proline,2mgL-1 N6-benzyladenine (BA), and 0.02mgL-1 α-naphthalene acetic acid (NAA) to induce the formation of adventitious shoots at the primary leaf node.In inducing shoot formation, this medium was superior to MS and B5 media even when all were supplemented with the same BA, NAA and proline levels.Explants from seedlings of the cultivar Peking produced an average of ca.20 shoots per explant after 4–5 weeks on this medium.Shoot formation was greater when a cotyledon remained attached to the explant.Shoot formation was also influenced by medium composition, explant orientation, age of donor seedling, and cultivar.Exogenous cytokinin (BA) was essential for shoot formation; proline and the fourfold-raised level of MS inorganic micronutrients caused a large increase in shoot number. © 1990, Gustav Fischer Verlag, Stuttgart. All rights reserved.