Genome-wide Association Study And ITRAQ Analysis Of TuMV Resistance On Non-heading Chinese Cabbage

The Brassica crops belong to the cruciferae family and mainly contain three subspecies:B.rapa ssp.Pekinensis,B.rapa ssp.Chinensis and B.rapa ssp.Rapa.The non-heading Chinese cabbage originating in China is a kind of broad-grown leafy vegetables with rich nutrition,short growth period and unique flavor,which is deeply loved by people around the world.Turnip mosaic virus(TuMV)is a member of the genus potato Y virus,which is the main pathogen that endangers the Brassica crops.The plants infected with TuMV will show symptoms of yellow,shrinkage and dwarfing,seriously affecting the quality and yield of non-heading Chinese cabbage.In this paper,we analyzed the resistance to TuMV of 83 non-heading Chinese cabbage by genome-wide association analysis and carried out the iTRAQ analysis on different period of ’49 caixin’ infected with TuMV to explore the mechanism of long distance movement of the virus,we then ran the RT-PCR to analyse the resistance related genes we selected,which was found that most genes were up-regulated after inoculation and the expression level fit the sequence results.1.The genome-wide association study based on the relative expression level of TuMV coat protein from 83 different varieties of non-heading Chinese cabbage which were inoculated with TuMV,and the SNPs were mainly mapped in 9 and 10 chromosomes,finally,17 disease related genes were screened to be tested in NHCC001,NHCC003 and Arabidopsis thaliana mutants by RT-PCR.Most relative expression levels of genes were up-regulated in resistant material of NHCC001 and down-regulated in susceptible material of NHCC003,which proved that the proteins were associated with resistance.The genes selected from GWAS were R genes,PR genes,J proteins,SEC 14 proteins,TF and methytransferase which participated in protein ubiquitination,methylation,ROS and HR.The resistance is involved in many resistance proteins and complex defense mechanisms.2.49 caixin was used as the experiment material and the stems and petioles in 7th(TuMV-7),14th(TuMV-14)and 21th(TuMV-21)days after inoculation and control before inoculation were sampled.With the iTRAQ-based proteomic technology,6043 distinct proteins were identified and 323,240,285,203,253,363 differentially expressed proteins were found in comparable pairs of TuMV-7/Control,TuMV-14/TuMV-7,TuMV-14/Control,TuMV-21/TuMV-7,TuMV-21/TuMV-14 and TuMV-21/Control respectively.We adopted function annotation analysis of all identified proteins and function enrichment analysis of all differentially expressed proteins,then we found plasmodesmata plays indispensable roles in TuMV long distance movement as well as Ca2+.Heat shock proteins and pathogenesis-related proteins actively fight against virus with the defense system of reactive oxygen species jointly.27 genes that may be associated with the resistance and virus long distance movement were screened and the genes related to resistance involved in Ca2+,PD,PM and the genes related to virus long distance movement involved in metabolic and secondary metabolic process,oxidation reaction,heat shock reaction and plant-pathogen pattern.24 genes of the selected genes were up-regulated and 3 genes were down-regulated and the expression trends fit the iTRAQ results,which proved the 27 genes were related to the virus long distance movement and resistance.