Phosphorylation of a WRKY transcription factor by MAPKs is required for pollen development and function in Arabidopsis.
Plant male gametogenesis involves complex and dynamic changes in gene expression. At present, little is known about the transcription factors involved in this process and how their activities are regulated. Here, we show that a pollen-specific transcription factor, WRKY34, and its close homolog, WRKY2, are required for male gametogenesis in Arabidopsis thaliana. When overexpressed using LAT52, a strong pollen-specific promoter, epitope-tagged WRKY34 is temporally phosphorylated by MPK3 and MPK6, two mitogen-activated protein kinases (MAPKs, or MPKs), at early stages in pollen development. During pollen maturation, WRKY34 is dephosphorylated and degraded. Native promoter-driven WRKY34-YFP fusion also follows the same expression pattern at the protein level. WRKY34 functions redundantly with WRKY2 in pollen development, germination, and pollen tube growth. Loss of MPK3/MPK6 phosphorylation sites in WRKY34 compromises the function of WRKY34 in vivo. Epistasis interaction analysis confirmed that MPK6 belongs to the same genetic pathway of WRKY34 and WRKY2. Our study demonstrates the importance of temporal post-translational regulation of WRKY transcription factors in the control of developmental phase transitions in plants.
Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America; Shanghai Center for Plant Stress Biology, Chinese Academy of Sciences, Shanghai, China.
Yuefeng
Y
Guan
Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
Xiangzong
X
Meng
Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
Reshma
R
Khanna
Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
Erica
E
LaMontagne
Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
Yidong
Y
Liu
Division of Biochemistry, Interdisciplinary Plant Group, and Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
Shuqun
S
Zhang
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D005718:Gametogenesis / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D018525:Germination / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics / Q000254:growth & development*; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000235:genetics*
D029681:Arabidopsis Proteins; D014157:Transcription Factors; C552478:WRKY34 protein, Arabidopsis; C436293:MPK6 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases