Wheat AGAMOUS LIKE 6 transcription factors function in stamen development by regulating the expression of <i>Ta APETALA3</i>

Abstract

Previous studies have revealed the functions of rice and maize <i>AGAMOUS LIKE 6</i> (<i>AGL6</i>) genes <i>OsMADS6</i> and <i>ZAG3</i>, respectively, in floral development; however, the functions of three wheat (<i>Triticum aestivum</i>) <i>AGL6</i> genes are still unclear. Here, we report the main functions of wheat <i>AGL6</i> homoeologous genes in stamen development. In RNAi plants, stamens showed abnormality in number and morphology, and a tendency to transform into carpels. Consistently, the expression of the B-class gene <i>TaAPETALA3</i> (<i>AP3</i>) and the auxin-responsive gene <i>TaMGH3</i> was downregulated, whereas the wheat ortholog of the rice carpel identity gene <i>DROOPING LEAF</i> was ectopically expressed in RNAi stamens. TaAGL6 proteins bind to the promoter of <i>TaAP3</i> directly. Yeast one-hybrid and transient expression assays further showed that TaAGL6 positively regulates the expression of <i>TaAP3 in vivo.</i> Wheat AGL6 transcription factors interact with TaAP3, TaAGAMOUS and TaMADS13. Our findings indicate that TaAGL6 transcription factors play an essential role in stamen development through transcriptional regulation of <i>TaAP3</i> and other related genes. We propose a model to illustrate the function and probable mechanism of this regulation. This study extends our understanding of <i>AGL6</i> genes.