Previous genetic and molecular biological studies have broadened our knowledge of WRKY transcription factor family and its functions in various biotic/abiotic stress responses. However, far less is known about the roles of the WRKY gene family in plant development.
Prof. YU Diqiu and his team of Xishuangbanna Tropical Botanical Garden (XTBG) studied the roles of two WRKY proteins, WRKY12 and WRKY13, in flowering time control under short day conditions in Arabidopsis. Their study showed that the two WRKYs regulate flowering under short day conditions.
To explore the potential regulatory roles of WRKYs in plant developmental processes, the researchers collected the available T-DNA insertion lines of WRKY genes and investigated their developmental phenotypes. They found that WRKY12 and WRKY13 had opposite roles in flowering-time regulation under short day conditions. They then examined the expression patterns of WRKY12 and WRKY13 by qRT-PCR analysis and found that expression patterns of WRKY12 and WRKY13 were negatively correlated.
The researchers performed promoter-swap assays in order to understand whether the negatively correlated expression patterns of WRKYs had different effects on flowering time. The results showed that WRKY12 and WRKY13 were regulated to function successively.
They then measured expression levels of two flowering-related MADS box genes (FUL and SOC1) in wrky12 and wrky13 mutants, and found that WRKY12 and WRKY13 oppositely regulated transcripts of flowering-related MADS box genes.
They generated transgenic lines expressing a WRKY12 or WRKY13 cDNA construct with an N-terminal MYC/HA tag under the control of their respective native promoter in the wrky12-2 and wrky13-1 mutant backgrounds, respectively (wrky12-2/PW12:W12 with MYC tag and wrky13-1/PW13:W13 with HA tag). The results showed that WRKY12 and WRKY13 directly regulated expression of FUL and FUL was a direct target of WRKY12 and WRKY13.
To further investigate the biological significance of the interactions between the WRKYs and DELLAs, the researchers performed transient expression assays. They found that WRKY12 and WRKY13 were partially involved in GIBBERELLIN INSENSITIVE (GA)-mediated flowering time control. WRKY12 was a positive regulator, while WRKY13 was a negative regulator, of flowering time.
The researchers thus concluded that WRKY12 and WRKY13 oppositely modulate flowering time under short day conditions.
The study entitled “The Arabidopsis WRKY transcription factors WRKY12 and WRKY13 oppositely regulate flowering under short-day conditions” has been published online in Molecular Plant.
Contact
YU Diqiu, Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China
E-mail: ydq@xtbg.ac.cn
Tel: +86 871 65178133
