Rapid In Vitro Plant Regeneration From Nodal Explant of Mucuna Gigantea—An Endangered Medicinal Legume

Abstract

Mucuna gigantea (Willd.) DC. (Fabaceae) is an underutilized endangered medicinal legume distributed in tropical Asia,
Japan, Australia, the Pacific islands and Africa. Almost all parts of the plant have been found to contain L-3,4-dihydroxy
phenylalanine (L-DOPA), a non-protein amino acid that works as a precursor for the neurotransmitter dopamine. Keeping in
view, efforts have been made to develop an efficient, quick and large scale propagation protocol using mature nodal segments
of M. gigantea. The aim of the research was to create a quick in vitro regeneration of shoot and root optimisation of the
cytokinin and auxin are required. Several cytokinins, 6-benzyladenine (BA), kinetin (Kin), meta-Topolin (mT), Thidiazorone
(TDZ) and auxins, Indole-3-butyric acids (IBA), α-Napthalene acetic acids (NAA) singularly or in combinations were
supplemented for in vitro shoot multiplication. Among them, BA was efficient in producing several shoots at an ideal dosage of
2.0 mg/l and IBA 0.5 mg/l for roots. The effectiveness of shoot regeneration was also controlled by the strength and NaCl
concentration in the basal media. When the NaCl concentration was lowered, the frequency of shoot regeneration tends to
increase up to a certain limit. On MS medium supplemented with 2.0 mg/l BA and 0.5 mg/l NAA, the highest response 83.3%
with peak number of multiple shoots c.a. 9.1 and maximum average shoot length 5.7 cm were standardised at four subcultures.
For up-scaling of shoots, in vitro nodal segments were harvested, cultured and highest shoot multiplication was
observed on MS+1.0 mg/l BA. In vitro shoots removed from proliferating shoot cultures were best encouraged to root on ½ MS
medium supplemented with an ideal concentration of 0.5 mg/l IBA with an average 3.1 root numbers with an average 68%
survival rate, the in vitro-raised plantlets with well-developed shoots and roots were successfully established in earthen pots
containing garden soil and nurtured in a greenhouse. The finding of this study is the first to show in vitro regeneration of Mucuna
gigantea. This plant regeneration procedure, would be valuable for ex situ conservation, reintroduction in wild habitat and
commercial application in the pharmaceutical industries, which will change the underutilized to utilized legume.