Effect of different growth regulators on organogenesis and total fresh weight gain in cultured leaf tissues of cowpea Walp
Ladeinde, T.A.O.; Soh, W.Y.
Phytomorphology (Delhi) 41(1-2): 99-107
ISSN/ISBN: 0031-9449 Accession: 031076464
Low (0.05 mg/l) and high (0.5 mg/l) levels of auxins - NAA, IBA and IAA and low (0.5 mg/l) and high (1.0 mg/l) levels of cytokinins - BAP, Kinetin and Zeatin were tested for their effects on organogenesis and fresh weight production in discs of leaf lamina with small veins, leaf midrib discs with midvein and petiole discs of a black Korean cultivar of cowpea, Vigna unguiculata (L.) Walp. Modifications of Murashige and Skoog's basal medium with the auxins alone produced root organogenesis from petioles at both the low and high levels except at low level of NAA while high level of IAA, in addition, stimulated root organogenesis in leaf midrib disc within two weeks of incubation. Also, root organogenesis was obtained at both low (0.05 mg/l NAA + 1.0 mg/l Kinetin) and high (0.5 mg/l NAA + 0.5 mg/l BAP, + 0.5 mg/l Kinetin, + 1.0 mg/l Zeatin) levels of NAA combined with the cytokinins in petioles while in leaf midrib disc, organogenesis was only obtained at high levels of NAA + cytokinins (0.5 mg/l NAA + 0.5 mg/l BAP, + 0.5 mg/l Kinetin + 1.0 mg/l Kinetin). Root organogenesis was stimulated in the leaf lamina disc only in 0.5 mg/l NAA + 1.0 mg/l Zeatin. The NAA and its combinations with cytokinins had higher gain in fresh weight for lamina and petiole + leaf midrib in general, compared to the other media tested. NAA and Zeatin combinations produced the highest gain for leaf midrib disc while high level of IAA produced the highest gain of petiole + leaf midrib disc. Tiny leaf discs produced only callus, the largest being in 1.0 mg/l 2,4-D + 0.5 mg/l Kinetin. Petiole disc retained green callus, some of which had organized tissues, for several days but no shoot regeneration so far. The implications of these results in plant regeneration and micropropagation are discussed.