THE TERMINAL FLOWER2 (TFL2) GENE CONTROLS THE REPRODUCTIVE TRANSITIONAND MERISTEM IDENTITY IN ARABIDOPSIS-THALIANA

A new mutant of Arabidopsis thaliana that initiates flowering early an d terminates the inflorescence with floral structures has been identif ied and named terminal flower2 (tfl2). While these phenotypes are simi lar to that of the terminal flower1 (tfl1) mutant, tfl2 mutant plants are also dwarfed in appearance, have reduced photoperiod sensitivity a nd have a more variable terminal flower structure. Under long-day and short-day growth conditions tfl tfl2 double mutants terminate the infl orescence without development of lateral flowers; thus, unlike tfl1 si ngle mutants the double mutant inflorescence morphology is not affecte d by day length. The enhanced phenotype of the double mutant suggests that TFL2 acts in a developmental pathway distinct from TFL1. The comp lex nature of the tfl2 single mutant phenotype suggests that TFL2 has a regulatory role more global than that of TFL1. Double mutant analysi s of tfl2 in combination with mutant alleles of the floral meristem id entity genes LEAFY and APETALA1 demonstrates that TFL2 function influe nces developmental processes controlled by APETALA1, but not those reg ulated by LEAFY. Thus, the TFL2 gene product appears to have a dual ro le in regulating meristem activity, one being to regulate the meristem response to light signals affecting the development of the plant and the other being the maintenance of inflorescence meristem identity.