Changes in free and conjugated indole-3-acetic acid during early stage of flower bud differentiation in Polianthes tuberosa

Tuberose (Polianthes tuberosa L. cv. Double) corms at the vegetative, early floral initiation, and flower bud differentiation stages were assayed for free indole-3-acetic acid (IAA), esterified IAA, and peptidyl IAA. The corms in the vegetative stage contained higher free IAA than those from the early floral initiation stage. Free IAA in corm tissues increased 2.7-fold at flower bud differentiation as compared to the vegetative stage. In the vegetative corms, a marked promotion of leaf differentiation was recorded. In contrast, corms from the early floral initiation stage contained less free IAA, whereas esterified IAA and peptidyl IAA increased dramatically. It is concluded that the level of free IAA in vegetative corms is correlated with leaf differentiation, and that the early floral initiation stage is correlated with a reduction in free IAA and an increase in IAA conjugates in the corms. Moreover, increases in free IAA and decreases in IAA conjugates in the floral differentiation stage, as compared to the early floral initiation stage, indicates that free IAA is correlated with flower development.