MADS-domain transcription factors both positively and negatively regulate the vegetative-to-reproductive transition in plants. The MADS-domain factors AGL (AGAMOUS-Like)15 and AGL18 act to repress the expression of FT (FLOWERING LOCUS T). FT functions as a mobile signal that results in developmental reprogramming at the shoot apical meristem and a shift from the production of leaves to the production of floral tissues. We examined the action of AGL15 and AGL18 relative to other MADS-domain proteins involved in the floral transition. When the floral repressors are sequentially removed by mutations, the plants flower at younger and younger ages. When AGL15 or AGL18 are over-expressed, the plants flower later and other developmental transitions, including floral organ abscission and senescence, are delayed.
Fernandez, D.E., C.-T. Wang, Y. Zheng, B.J. Adamczyk, R. Singhal, P.K. Hill, and S.E. Perry (2014). The MADS-domain factors AGAMOUS-LIKE15 and AGAMOUS-LIKE18, along with SHORT VEGETATIVE PHASE and AGAMOUS-LIKE24, are necessary to block floral gene expression during the vegetative phase. Plant Physiol. 165: 1591-1603.
Adamczyk, B.J., M.D. Lehti-Shiu, and D.E. Fernandez (2007). The MADS domain factors AGL15 and AGL18 act redundantly as repressors of the floral transition in Arabidopsis. Plant J. 50: 1007-1019.
Fernandez, D.E., G.R. Heck, S.E. Perry, S.E. Patterson, A.B. Bleecker, and S.-C. Fang (2000). The embryo MADS domain factor AGL15 acts post-embryonically: inhibition of perianth senescence and abscission via constitutive expression. The Plant Cell 12: 183-198.