The TERMINAL FLOWER2 (TFL2) Gene Controls the Reproductive Transition and Meristem Identity in Arabidopsis thaliana

Abstract

Abstract A new mutant of Arabidopsis thaliana that initiates flowering early and terminates the inflorescence with floral structures has been identified and named terminal flower2 (tfl2). While these phenotypes are similar to that of the terminal flower1 (tfl1) mutant, tfl2 mutant plants are also dwarfed in appearance, have reduced photoperiod sensitivity and have a more variable terminal flower structure. Under long-day and short-day growth conditions tfl1 tfl2 double mutants terminate the inflorescence without development of lateral flowers; thus, unlike tfl1 single mutants the double mutant inflorescence morphology is not affected by day length. The enhanced phenotype of the double mutant suggests that TFL2 acts in a developmental pathway distinct from TFL1. The complex nature of the tfl2 single mutant phenotype suggests that TFL2 has a regulatory role more global than that of TFL1. Double mutant analysis of tfl2 in combination with mutant alleles of the floral meristem identity genes LEAFY and APETALA1 demonstrates that TFL2 function influences developmental processes controlled by APETALA1, but not those regulated by LEAFY. Thus, the TFL2 gene product appears to have a dual role 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.