Control of lateral organ development and flowering time by the Arabidopsis thaliana MADS-box Gene AGAMOUS-LIKE6

Abstract

SUMMARYMADS-domain transcription factors play pivotal roles in various developmental processes. The lack of simple loss-of-function phenotypes provides impediments to understand the biological function of some of the MADS-box transcription factors. Here we have characterized the potential role of the Arabidopsis thaliana AGAMOUS-LIKE6 (AGL6) gene by fusing full-length coding sequence with transcriptional activator and repressor domains and suggest a role for AGL6 in lateral organ development and flowering. Upon photoperiodic induction of flowering, AGL6 becomes expressed in abaxial and proximal regions of cauline leaf primordia, as well as the cryptic bracts subtending flowers. In developing flowers, AGL6 is detected in the proximal regions of all floral organs and in developing ovules. Converting AGL6 into a strong activator through fusion to the VP16 domain triggers bract outgrowth, implicating AGL6 in the development of bractless flowers in Arabidopsis. In addition, ectopic reproductive structures form on both bracts and flowers in gAGL6::VP16 transgenic plants, which is dependent on B and C class homeotic genes, but independent of LEAFY. Overexpression of both AGL6 and its transcriptional repressor form, AGL6::EAR, causes precocious flowering and terminal flower formation, suggesting that AGL6 suppresses the function of a floral repressor.

Overexpression of OsMYB1R1–VP64 fusion protein increases grain yield in rice by delaying flowering time

“…VP16 usually changed transcriptional repressors into activators, or enhanced transcriptional activation activity, leading to enhanced or opposite phenotypes compared to those produced by knockout mutations in Arabidopsis [56][57][58][59]. Recently, VP16 has been used in rice to investigate the function of TFs in determining flowering time [60,61].…”

FLOWERING LOCUS C EXPRESSOR Family Proteins Regulate FLOWERING LOCUS C Expression in Both Winter-Annual and Rapid-Cycling Arabidopsis

“…In this approach, a transcriptional activator is fused to a 12-amino acid (LDLDLELRLGFA) ERF-associated amphiphilic repression (EAR) motif repression domain (SRDX). Chimeric Repressor Gene Silencing Technology has successfully been applied in a number of cases to create transcription factor-SRDX fusions that act to repress the expression of genes that are normally activated by the native transcription factor (Hiratsu et al, 2003;Fujita et al, 2005;Takase et al, 2007;Koo et al, 2010). Constructs containing FLX4 alone or fused to the repressor domain (FLX4::RD) were transformed into FRI-Col plants.…”

Relationship between MdMADS11 Gene Expression and Juvenility in Apple

“…DAL1 is considered to be the conifer homolog of Arabidopsis AGAMOUS-LIKE6 (AGL6). Because only a few reports have shown the role of AGL6 in Arabidopsis with respect to bract development and floral patterning (Koo et al, 2010), there is no comprehensive understanding of the developmental roles of AGL6. DAL1 expression increases with age in Norway spruce and promotes flowering in Arabidopsis (Carlsbecker et al, 2004).…”