Interaction Between Strigolactone and Cytokinin on Axillary and Adventitious Bud Development in Zantedeschia

Interaction Between Strigolactone and Cytokinin on Axillary and Adventitious Bud Development in Zantedeschia

Strigolactones are known to be involved in the control of branching, particularly axillary bud outgrowth. However, the effect of strigolactone on adventitious bud development is presently unknown, and the interaction of strigolactone with cytokinin on bud outgrowth has not been fully understood. Using a germination assay, high strigolactone levels were detected in a low-branched cultivar (Best Gold) but was less abundant in a high-branched cultivar (Goldilocks), particularly at an early stage of the growth cycle when branching was not visibly evident. In contrast, the concentration of cytokinins directly correlated with branching, suggesting an antagonistic interaction between strigolactones and cytokinins on branching. Supporting this hypothesis, strigolactone reduced the cytokinin stimulation of both axillary and adventitious shoot number in Zantedeschia grown in vitro. The reduced cytokinin concentration in a phenotypically low branched cultivar may have been associated with the inhibition effect of strigolactones. Hence, the fact that the alteration of branching in Zantedeschia or other horticultural species depends on the hormonal balance between these two hormones is quite likely. The idea may be useful for the generation of plants of desired branching at least within the in vitro system.