FALSIFLORA AND ANANTHA CONTROL EARLY STAGES OF FLORAL MERISTEM DEVELOPMENT IN TOMATO (LYCOPERSICON-ESCULENTUM MILL)

The shoot apical meristem of tomato gives rise to a relatively fixed n umber of vegetative nodes before converting to an inflorescence merist em. Growth of the plant after inflorescence initiation is continued by a sympodial bud in the axil of the last-formed leaf. We show that the inflorescence meristem produces flower meristems not as lateral primo rdia, but by a series of nearly equal divisions, each time yielding a flower meristem and an inflorescence meristem. We describe two mutants , falsiflora and anantha, that block the acquisition of floral meriste m identity by the products of the inflorescence meristem. In both muta nts the vegetative meristem successfully converts to an inflorescence meristem (although this is delayed in falsiflora), and the inflorescen ce meristem functions morphologically the same as in the wild type. Bu t determinate flower meristems are replaced by indeterminate prolifero us shoots with a combination of inflorescence and vegetative character s. The falsiflora inflorescence is very leafy with substantial interno de elongation and may easily reach a meter in length. The anantha infl orescence is reminiscent of the common cauliflower variant of Brassica (B. oleracea var. botrytis). Leaves within the anantha inflorescence, although still present, are highly suppressed. Normal flowers never f orm, but occasionally some aberrant floral structures may be found in very large anantha inflorescences. Based on phenotypic comparison, fal siflora appears to be blocked at an earlier stage than is anantha. Con sistent with this, falsiflora is completely epistatic to anantha. We d iscuss our findings in the context of characterized meristem identity mutants in other species, and of partial flowering experiments indicat ing that the vegetative to floral transition is, at least in many spec ies, a series of small steps rather than an all or none transformation .