Study On The Drought Resistance Function Of The Mitogen-activated Protein Kinase Gene MPK6 Of L. Japonicus

The drought environment triggers various responses of plants to improve drought stress tolerance and survivability.Mitogen-activated protein kinase(MAPK)is an important regulator of the MAPK cascade in plants under drought conditions.In particular,the mitogen-activated protein kinase gene MPK6 plays an important role in the response of plants to drought stress.In this study,the physicochemical properties,protein structure,subcellular location,and tissue-specific expression pattern of the MPK6 gene of Lotus corniculatus were firstly analyzed by bioinformatics,and then the MPK6 expression vector was constructed and transformed into Arabidopsis thaliana.Explore the molecular mechanism of MPK6 gene involved in signal transduction to regulate Arabidopsis response to drought stress to analyze the drought resistance function of MPK6 gene.1.Constructing a genetic evolutionary tree learned that the MPK6 gene is closely related to the MAPK family genes of legumes.Prediction of physicochemical properties and protein structure found that MPK6 protein is a hydrophobic protein kinase that does not have a transmembrane structure and participates in intracellular signal transmission.Functional protein association network prediction found that MPK6 gene has the strongest interaction with dual-specific protein phosphatase MKP2,followed by protein tyrosine phosphatase PTP1,mitogen-activated protein kinase phosphatase MKP1,and mitogen-activated protein kinase kinase MKK2.MPK6 gene is subcellular located in the nucleus.Tissue-specific expression analysis found that MPK6 gene is expressed in roots,stems,leaves,flowers,and seeds of L.corniculatus,with the highest expression in roots and leaves.2.By constructing overexpression and suppression expression vectors and transforming them into Arabidopsis,the F₃ generation positive seeds were screened for drought resistance research.GUS staining and protein activity detection showed that MPK6 overexpression increased the activity of MPK6 protein,which in turn induced root growth,maintained leaf water content,and prevent leaf chlorosis under drought stress and other mechanical changes to improve the drought resistance of A.thaliana.Antioxidant tests showed that drought-induced MPK6 gene expression increased the antioxidant capacity of A.thaliana,mainly through the MAPK cascade metabolic pathway to regulate reactive oxygen species(ROS)and eliminate oxidative damage,maintain cell membrane stability,and reduce cell death.Observation of paraffin section tissues showed that MPK6 overexpression can effectively alleviate the lignification and cornification of A.thaliana leaves.3.Combined with the pull-down analysis of MPK6 protein,it is found that the signal transduction mechanism of MPK6 gene involved in drought resistance of L.corniculatus mainly responds to various mechanisms such as physiological metabolism regulation,regulation of cell structure,and ROS clearance.Under drought stress and restoration of water supply,the physiological changes,root morphology,and growth cycle of A.thaliana have been tested and found that the mechanism of MPK6 signal transduction to regulate A.thaliana drought resistance is mainly to promote root growth to obtain more water,maintain cell homeostasis,and participate in metabolic regulation to establish an antioxidant system to adapt to the arid environment,but MPK6 signal regulation has no significant effect on the growth cycle of A.thaliana.Therefore,it is defined that the main ways that MPK6 gene plays a role in regulating drought resistance in MAPK cascade signal transduction are drought avoidance and drought tolerance,and the two mechanisms coordinately regulate plants to respond to drought stress.