Effects of cytokinin on adventitious root formation in callus cultures ofVigna unguiculata (L.) walp |
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Authors: | Woong-Young Soh Pil-Son Choi Duck-Yee Cho |
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Institution: | (1) Department of Biological Sciences, Chonbuk National University, 561-756 Chonju, Korea;(2) Department of Biology, Chonbuk, 565-701 Samrye, Korea |
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Abstract: | Summary Yellowish compact callus, induced from cowpea hypocotyls on Murashige and Skoog(MS) medium (1962) containing 0.2 mg/l(0.93
μM) kinetin and 0.4 mg/l (1.81 μM) 2,4-dichlorophenoxyacetic acid (2,4-D), was subcultured on MS medium containing cytokinin alone, auxin alone, or auxins
plus cytokinins in order to determine the effect of cytokinins on root organogenesis in callus cultures. The callus actively
proliferated on the same medium but did not show any organogenic activity macroscopically as well as microscopically. On medium
with N6-benzyladenine (BA) and 1-naphthaleneacetic acid (NAA), the yellowish compact callus first changed to pale green compact callus
and then many green spots appeared on its surface under light culture. But the yellowsih compact callus remained yellowish
and white spots appeared on its surface in dark culture. These spots gradually became white nodular structures. Adventitious
root formation from the nodular structures occurred not only on the same medium, but also on medium with either auxin or cytokinin
but not both. Yellowish compact callus on medium with auxin alone was transformed to yellowish friable callus, which did not
develop adventitious roots. The yellowish friable callus could gain rhizogenic activity only after morphological modification
to pale green compact callus on medium with auxin plus cytokinin. The modified callus did not form adventitious roots on medium
with auxins but only with cytokinins. Therefore, it is suggested that cytokinins have stimulating effects on root formation
from callus that previously did not show rhizogenic activity on medium with auxins alone. In addition, the rhizogenic potential
of cowpea callus was discriminated from that of leaf explants, which formed adventitious roots directly on medium with auxin
alone. |
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Keywords: | cowpea rhizogenesis growth regulators callus types |
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