The Solanum Lycopersicum SlWDR204 Gene Positively Regulates Plant Drought Stress And Plant Height

The ubiquitin-proteasome pathway is an important system for intracellular modification and degradation of proteins.This pathway activates and connects ubiquitin molecules to substrate proteins through the action of three enzymes: E1 ubiquitin activating enzyme,E2 ubiquitin binding enzyme,and E3 ubiquitin ligase.The activity,stability or cell localization of the substrate protein will be changing with specifically modify by the ubiquitin protein.This pathway regulates plant growth development and stress respond,playing an important role in plant disease resistance,drought resistance,salt resistance,morphogenesis and hormone synthesis and other physiological activities.CRL4(CUL4-RING E3 ubiquitin ligase)is one of the recently discovered E3 ubiquitin ligases with rich functions and regulatory mechanisms.The ubiquitin ligase is composed of three parts.CUL4 is the scaffold protein of the ubiquitin ligase.DNA damage connexin(DDB1)is the core component.And the substrate WD40 family of connexins.With the WD40 protein binding to CUL4-DDB1,it forms the E3 ubiquitin ligase complex CUL4-DDB1-WD40,which targets the modification of different substrate proteins to regulate plant growth and development and stress response.This study found that the substrate connexin Sl WDR204 of Solanum lycopersicum E3 ubiquitin ligase is involved in regulating the plant's responding drought stress and plant height development.RT-PCR was used to detect the expression of the Sl WDR204 gene in Solanum lycopersicum tissues,including roots,stems,leaves,flowers,and fruits at different stages of development(mature green fruits,break red fruits,and ripe red fruits).The gene is expressing in both tissues,and the expression level is higher in the break red fruit stage and the red fruit period of fruit development,and is lower in mature green fruits.The Sl WDR204 gene was cloned from the Solanum lycopersicum genome.And a Sl WDR204-GFP fusion expression vector was constructed.The fusion protein was expressed transiently in tobacco leaves.The laser confocal observation revealed that Sl WDR204 was located in the nucleus.Through molecular biology technology,the overexpression vector of Sl WDR204 gene and down-regulated expression vector were constructed,and the transgenic plants were obtained by Agrobacterium tumefaciens.Observation found that the down-regulated expression of the Sl WDR204 gene reduced the plant's tolerance to drought stress.Overexpression of the Sl WDR204 gene resulted in increased drought tolerance of the plant,indicating that the gene is regulating theSolanum lycopersicum response to drought stress.Compared with the wild type,the over-expressed Sl WDR204 transgenic plants had significantly higher plant heights,but the down-regulation of Sl WDR204 did not result in a decrease in plant height,suggesting that there are other functionally redundant WD40 proteins in the pathway that regulates plant height.The yeast two-hybrid experiment was used to screen the proteins in the Solanum lycopersicum library that interacted with the Sl WDR204 protein.,and found that the transcription factor Sl SPL3 interacted with the Sl WDR204 protein.Subcellular localization showed that Sl SPL3 was localized in the nucleus,indicating that Sl WDR204 may interact with Sl SPL3 in the nucleus.Sl WDR204 may play a role by ubiquitinating Sl SPL3 protein.In this project,the study of the function of Solanum lycopersicum Sl WDR204 gene provides a new theoretical understanding for plant ubiquitination process to regulate plant physiological activities.