SlWRKY80 recruits SlHDA1 to regulates the tomato fruit ripening and color transformation

Abstract Fruit ripening involves key transcription factors (TF). Despite the established importance of WRKY TFs in plant development, the involvement of WRKY and its underlying mechanism in the regulation of fruit ripening and color transformation remain unclear. Here, we discovered a phenomenon where SlWRKY80 is involved in the ripening and color transformation of tomato. Overexpression of SlWRKY80 shortened the color transition cycle of tomato fruit, whereas loss-of-function mutation in SlWRKY80 delays this process. On the 7 th day after the color breakdown (Break+7), the fruit color was bright red in SlWRKY80 -overexpression lines. SlWRKY80 could bind to downstream promoters of SlSGR1 and SlPSY1 , thereby exerting a positive regulatory effect on the expression levels of SlSGR1 and SlPSY1 . This regulatory activity led to the facilitation of chlorophyll a decomposition and carotenoid synthesis during the transition of fruit color, ultimately accelerating fruit ripening and color change. The SlWRKY80 knockout lines ( slwrky80 cr -3 and slwrky80 cr -4) showed light red. Thr (The 69 th amino acid) mutated to Ser of SlWRKY80 ( slwrky80 cr -46), SlHDA1 was recruited as a regulatory factor to enhance the regulation of downstream SlPSY1 by SlWRKY80 , and inhibited the SlSGR1 expression by SlWRKY80 which maybe the reason why the slwrky80 cr -46 knockout lines exhibited brown color. In conclusion, SlWRKY80 regulates the expression of SlSGR1 and SlPSY1 by recruiting SlHDA1, thereby regulating chlorophyll decomposition and carotenoid synthesis, and further participating in fruit maturation and related fruit color formation. This research has important guiding significance for breeding tomato germplasm with excellent commercial traits.