Dormancy and Flowering Are Regulated by the Reciprocal Interaction Between Cytokinin and Gibberellin in <Emphasis Type="Italic">Zantedeschia</Emphasis> |
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Authors: | Arvind Kumar Subbaraj Keith Allen Funnell David John Woolley |
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Institution: | (1) Institute of Natural Resources, Massey University, Private Bag 11 222, Palmerston North, 4442, New Zealand |
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Abstract: | Floral productivity of Zantedeschia is dependent on the conversion rate of buds to shoots, which is controlled by varying intensities of para- (apical dominance),
endo- (dormancy), and ecodormancy. We present evidence of cross-talk between cytokinin and gibberellin in their complementary
roles to alleviate bud dormancy and enhance flowering in a perennial geophyte. We assessed the impact of cytokinin and gibberellin,
applied alone and in sequential combinations, on bud fate during three phases along the ontogeny of growth, which coincide
with the progressive transition of buds from apical dominance to dormancy. Given that cytokinin can stimulate branching and
gibberellin can induce flowering in Zantedeschia, we measured these phenotypic responses as parameters of bud commitment. The efficacy of cytokinin alone to stimulate branching
declined with the transition to dormancy (phase 1 = 3.8 ± 0.2 shoots; phase 3 = 1.0 ± 0.3 shoots). To sustain branching during
this transition, a sequential application of gibberellin was necessary. Gibberellin alone failed to stimulate branching. The
efficacy of gibberellin alone to stimulate flowering diminished with the transition to dormancy. Any flowering during this
transition occurred only after the sequential application of cytokinin. Cytokinin alone failed to stimulate flowering. Alleviating
bud dormancy and enhancing flowering in Zantedeschia, achieved by the reciprocal cross-talk between cytokinin and gibberellin, contributes to the pool of evidence drawing common
mechanisms between dormancy and flowering and may have commercial implications. |
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