Expression Analysis Of ARFs And WRKYs In Pathogenesis Of Tomato Bacterial Wilt

Solanum lycopersicum is an annual or perennial herb of the Solanaceae.Tomato is native to South America and cultivated worldwide.Tomato bacterial wilt caused by Ralstonia solanacearum is soil-borne and has a wide range of hosts,causing huge losses in tomato production.The study on the transcription factors related to bacterial wilt resistance in tomato may guide the disease prevention and the disease resistance breeding.This study analyzed the expression of ARF and WRKY transcription factors in the pathogenesis of tomato bacterial wilt.The main results are as follows:1.The seedlings with 4 to 5 true leaves of resistant material Hawaii7996 and susceptible cultivar M82 were inoculated with Ralstonia solanacearum.The samples of roots and stems were collected at 3 days and 5 days after inoculation and were subjected to transcriptome sequencing.Sequencing data showed that there were more differentially expressed genes in the roots than in the stems after inoculation.This may be due to bacteria entering the plants through roots.At 5 days after of inoculation,the differentially expressed genes in the roots were much more than those at 3 days.It may be due to the fact that more resistance genes or resistance-related genes in the defense-control network of the plants were induced to express after 5 days of inoculation.This mechanism contributes to the resistance to the infection of Ralstonia solanacearum.2.Through KEGG pathway enrichment analysis,it was found that in the roots of Hawaii7996 and M82,the phytohormone signal transduction pathway were co-enriched at 3 days after inoculation,and the pathways of glycosaminoglycan and ribose sugar metabolism,glutathione metabolism and interaction between plants and pathogenic bacteria were coenriched at 5 days after inoculation;in the stems of Hawaii7996 and M82,the pathway of processed in the endoplasmic reticulum was co-enriched at 3 days after inoculation,and the pathways of glutathione metabolism and unsaturation,synthesis of fatty acids were coenriched after 5 days of inoculation.3.After inoculation with Ralstonia solanacearum,there was a difference in ARF6 expression between the resistant and susceptible varieties.It was speculated that ARF6 may negatively regulate tomato resistance to bacterial wilt.WRKY40 was up-regulated in roots at 3 days and 5 days after inoculation,but the expression level in Hawaii7996 was about 2 times that of M82.It was speculated that this gene may play a positive role in the resistance to bacterial wilt.WRKY53 was continuously up-regulated in Hawaii7996 stems after 3 and 5 days of inoculation,but it was only up-regulated in M82 at 3 days after inoculation,suggesting that it may be involved in mediating tomato resistance to bacterial wilt.4.Twelve differentially expressed genes were randomly selected for qRT-PCR validation.The results showed that the expression trends of these genes were consistent with RNA-seq,indicating that the RNA-seq sequencing results were reliable.In summary,ARF6?WRKY40 and WRKY53 play a regulatory role in the defense against R.solanacearum infection,but its mechanism of action still needs to be explored.There is no report yet on ARF6 regulateing the bacterial wilt resistance in tomato.