Functional Analysis Of Plasmalemma Calcium Channel Gene CNGC2 On Plant Response To Bacterial AHL And Transcriptomic Analysis Of AHL-induced Plant Disease Resistance

As quorum sensing signal molecules of Gram-negative bacteria,N-acyl-homoserine lactones(AHLs)can induce physiological activities of plants.As a plasma membrane calcium channel of Arabidopsis thaliana,CNGC2 plays an important role in plant growth and development.In this study,the methods of plant physiology,molecular biology,cell biology and so on were used to explore the involvement of CNGC2 in plant response to 3OC8-HSL.Transcriptomic changes of 3OC8-HSL-induced plant disease resistance were also analyzed by RNA-seq method in Arabidopsis.To clarify the mechanism of plant response bacterial AHL will provide a theoretical foundation for exploring the new biotic pesticides.In this study,the functional deletion mutant dnd1 of CNGC2 was used to investigate whether the physiological changes induced by AHL were related to CNGC2.The root length phenotype,disease resistance and calcium ion level of Arabidopsis thaliana were detected.The results showed that 3OC8-HSL treatment could significantly promotethe primary root growth,enhance disease resistance and increase the level of calcium ion in cells.in the wild type of Arabidopsis thaliana Col-0.However,the treatment effects of 3OC8-HSL was insensitive even opposite in dnd1 murant,hich indicated that CNGC2 played an important role in plant response to bacterial AHL.The effect of AHL on the expression of CNGC2 gene in plants was analyzed by qRT-PCR.The results showed that the expression of CNGC2 gene could be significantly up-regulated by 3OC8-HSL after pathogen Pst.DC3000 infection.Although AHL itself did not affect the expression of CNGC2 gene in plants,it could make plants in priming status.Once the pathogen is discovered,3OC8-HSL can more rapidly,violently and persistently up-regulate the expression of CNGC2 gene and activate the immune system in 3OC8-HSL-treated plant than in non-3OC8-HSL-treated plant.These result indicated that CNGC2 was involved in 3OC8-HSL induced plant disease resistance.Transcriptomic analysis was done in Arabidopsis with or without 3OC8-HSL pre-treatment before soft rot pathogen EC1 infection.The time point of EC1 infection was selected at just before rot symptom occurred.TThe differential gene expression were analyzed by RNA-seq,and then differential expressed gene function and pathway analysis were done according GO and KEGG databases.The results showed that the regulatory effect of 3OC8-HSL itself on plant transcriptom was limited,in which only 16 genes were significantly different expressed,and most of the functions were focus on plant.growth and development;After infection,the expression of 651 genes were significantly changed,and a large number of disease-resistant genes were expressed increasingly.Most of the different expressed genes(DEGs)were classified in immune and biotic stress response and belonged to defense signaling pathways.These results indicated that 3OC8-HSL enhanced plant disease resistance by activating plant innate immunity system,which provide theoretical bases and study material for exploring new biotic pesticides.