A RING-type E3 ligase controls anther dehiscence by activating the jasmonate biosynthetic pathway gene DEFECTIVE IN ANTHER DEHISCENCE1 in Arabidopsis.
Suppression of expression of DAF [DEFECTIVE IN ANTHER DEHISCENCE1 (DAD1)-Activating Factor], a gene that encodes a putative RING-finger E3 ligase protein, causes non-dehiscence of the anthers, alters pollen development and causes sterility in 35S:DAF RNAi/antisense Arabidopsis plants. This mutant phenotype correlates with the suppression of DAF but not with expression of the two most closely related genes, DAFL1/2. The expression of DAD1 was significantly reduced in 35S:DAF RNAi/antisense plants, and complementation with 35S:DAF did not rescue the dad1 mutant, indicating that DAF acts upstream of DAD1 in jasmonic acid biosynthesis. This assumption is supported by the finding that 35S:DAF RNAi/antisense plants showed a similar cellular basis for anther dehiscence to that found in dad1 mutants, and that external application of jasmonic acid rescued the anther non-dehiscence and pollen defects in 35S:DAF antisense flowers. We further demonstrate that DAF is an E3 ubiquitin ligase and that its activity is abolished by C132S and H137Y mutations in its RING motif. Furthermore, ectopic expression of the dominant-negative C132S or H137Y mutations causes similar indehiscence of anthers and reduction in DAD1 expression in transgenic Arabidopsis. This result not only confirms that DAF controls anther dehiscence by positively regulating the expression of DAD1 in the jasmonic acid biosynthesis pathway, but also supports the notion that DAF functions as an E3 ubiquitin ligase, and that the conserved RING-finger region is required for its activity.
Institute of Biotechnology, National Chung Hsing University, Taichung, 40227, Taiwan.
Yan-Jhu
YJ
Peng
Ching-Fang
CF
Shih
Jun-Yi
JY
Yang
Choon-Meng
CM
Tan
Wei-Han
WH
Hsu
Yu-Pei
YP
Huang
Pei-Chun
PC
Liao
Chang-Hsien
CH
Yang
D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D035264:Flowers / Q000235:genetics / Q000378:metabolism*; D054883:Oxylipins / Q000378:metabolism*; D054466:Phospholipases A1 / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D018076:DNA, Complementary; D054883:Oxylipins; C011006:jasmonic acid; D044767:Ubiquitin-Protein Ligases; C445094:DAD1 protein, Arabidopsis; D054466:Phospholipases A1