Molecular Mechanism Of SlTCP24/29 Regulating Compound Leaf Development And SlMPP6 Improving Resistance In Tomato

Tomato is an important fresh fruit vegetable,which is widely loved by the public,and it is widely studied as a model research plant.Development and resistance are always linked together.Leaves are the main place of plant photosynthesis and the main organ to perceive the aboveground environmental conditions.Tomato is a typical compound leaf development plant,and the leaves are complex and diverse.The development of tomato compound leaf is of great significance to improve the plant response to stress and improve the crop yield.As the second largest fungal disease,gray mold has infected most species,and the main effect disease resistance gene has not been cloned in plants.The control of gray mold is mainly chemical control,and its control effect is poor and the environmental harm is great.It is necessary to study the disease resistance mechanism of tomato to gray mold and cultivate the varieties of gray mold.In previous studies,we found that SlTCP24/29 may be involved in the regulation of tomato compound leaf development and SlMPP6 may be involved in resistance to gray mold,respectively.The function of these three genes in tomato was investigated by techniques and methods such as transgene,subcellular localization,gene knockout,EMSA,yeast single / double hybrid,Co-IP,and identification of gray mold inoculation.The main findings are divided following two points:(1)The leaf pattern of tomato compound leaf development regulators SlTCP24 and SlTCP29: SlTCP24 and SlTCP29 double knockout lines became complicated with increased leaflet numbers.The yeast two-hybrid and luciferase complementation experiments(LCI)validation showed that SlTCP24 and SlTCP29 can form both homodimers and heterodimers.Validation by yeast two-hybrid and Co-IP methods found that SlTCP24 and SlTCP29 can interact with the leaf polarity regulator SlAS2 protein,and that SlAS2 is involved in inhibiting the formation of SlTCP24 and SlTCP29 to homo or heterodimers.SlTCP24 and SlTCP29 can bind to the TCP cis-acting elements of the SlCKX2 promoter to jointly promote SlCKX2 transcription.In SlTCP24 and SlTCP29 double knockout lines,transcript levels of SlCKX2 were reduced and cytokinin levels increased.The results of this study identify two key regulators of compound leaf development and cytokinin content in tomato.Based on the observations of this study,a regulatory model of compound leaf development is proposed.(2)Botrytis cinerea resistance regulator gene SlMPP6 in Tomato: Through subcellular localization analysis,SlMPP6 was found to be a conserved nuclear protein,which is mainly expressed in tomato flowers and fruit during the color breaking stage.SlMPP6 is induced by B.cinerea,with high expression levels in disease-resistant materials and low expression in susceptible materials.The transgenic function validation showed that the height of SlMPP6-OE lines increased and the exposed degree of stigma decreased under high temperature;in the early stage of SlMPP6 knockout lines,the styles increased significantly and the exposure rate increased.High temperature induced SlMPP6 protein degradation,and excessive amounts of SlMPP6 reduced cell death.Identification of resistance found that SlMPP6-OE lines were more resistant and knockout lines were more susceptible to B.cinerea.By yeast two-hybrid,luciferase complementary experiments and immunoprecipitation validation SlMPP6 and exosome subunit SlRRP40 protein interaction,they are in regulating sno RNA and MRP RNA expression play the opposite role,SlRRP40 is located in the nucleus and in the cell membrane,transcriptional level also accumulated in flowers and fruit during the color breaking stage,SlRRP40-OE lines were more susceptible to B.cinerea,RIP-seq analysis found that SlMPP6 protein binds RNA from genes in m RNA surveillance,RNA in the RNA degradation pathway,also binds RNA from genes in the disease resistance pathway,transcriptomic data analysis found that SlMPP6 may mainly through the hormone signal transduction pathway genes and plant disease interaction pathway regulation of tomato resistance to B.cinerea.