Regulation of ethylene-responsive SlWRKYs involved in color change during tomato fruit ripening. Issue 1 (December 2017) - Wang, Ling
Abstract WRKY transcription factors (TFs) play important roles in stress responsesin planta . However, the function of WRKY TFs in the regulation of fruit ripening is unclear. Here, 23 tomatoSlWRKYs that are similar to ethylene-responsiveWRKY genes from other plant species, or show up-regulation during fruit ripening in previous genome-wide study, were selected, and their function in fruit ripening was investigated. TwelveSlWRKYs were found to be responsive to ethylene (SlER-WRKYs ), showing expression patterns similar to those of genes related to fruit ripening. EightSlER-WRKYs —SlWRKY16, 17, 22, 25, 31, 33, 53, and 54, detected in the nuclei—interacted with and activated the promoters of 4 genes related to color change:Pheophytin Pheophorbide Hydrolase (SlPPH ), Pheophorbide a Oxygenase (SlPAO ), Phytoene Synthase 1 (SlPSY1 ) andPhytoene Desaturase (SlPDS ). Yeast two-hybrid and bimolecular fluorescence complement (BiFC) assays in Arabidopsis protoplasts indicated that protein interactions occurred between SlWRKY17 and SlRIN, SlERF2b or SlERF7; SlWRKY33 and SlERF7; SlWRKY54 and SlERF2b; and SlWRKY16 and SlWRKY17. Suppression ofSlWRKY 16, 17, 53 or 54 by virus-induced gene silencing (VIGS) retarded the red coloration of the fruit. Our study provides comprehensive molecular evidence that WRKY TFs function in fruit ripening, particularly in color change, and are linked to the intricate regulatory network of other ripening regulators.