| Apple ring rot is an important disease in apple production,and selecting apple varieties with strong disease resistance is the most economical and environmentally friendly measure to control this disease.This study identified the resistance levels of 11apple varieties to apple ring rot fungus.The Transcriptome sequencing data of apple varieties with different disease resistance levels were analyzed to screen the genes related to resistance to Rhizoctonia solani.Further analysis of the activity and changes in plant antioxidant enzymes,disease related proteins,JA and SA hormones,reactive oxygen species content,and phenolic related metabolites,to clarify the differential resistance mechanisms of different apple varieties against rotavirus.The results are as follows:1.By combining indoor artificial inoculation of branches and field natural disease investigation,it was determined that there are significant differences in the resistance of different apple varieties to apple ring rot fungus.’Meile’and’Yanfu 3’are highly susceptible varieties,’Jindugala’,’Pinova’,’Ganhong’and’Changyanghong’are moderately susceptible varieties,while’Saijin’’Huajin’’Hongyu’’Zaohong’and’Huamei’are highly resistant varieties.2.Analysis of branch Transcriptome data after inoculation of Rhizoctonia solani in’Huamei’and’Meile’:（1）Comparing the Transcriptome data before and after inoculation of two varieties,4538 unique disease resistance genes were found in the resistant variety’Huamei’.（2）By performing GO functional annotation on the genes of two apple varieties,it was found that 940 unique genes were annotated by GO in’Huamei’,of which 654 were upregulated and 286 were downregulated.（3）KEGG metabolic pathway analysis of two apple varieties revealed that 2178 unique genes were annotated with KEGG in’Huamei’,of which 1412 were upregulated and 766 were downregulated.3.Combined with transcriptome data and q RT-PCR technology,the changes of related substances and gene expression of Apple Resistance to ring rot before and after inoculation were clarified.The lignin content and the expression levels of key genes F5H1,HCT1,CCR2,and COMT1 in the lignin synthesis pathway of’Huamei’are significantly higher than those of’’Meile’in disease resistant varieties The activity of plant defense enzymes SOD,PPO,PAL,and CHT in’Huamei’rapidly increased after inoculation,while the activity of POD,CAT,and APX did not show a significant upward trend after inoculation.Subsequently,they were higher than’Meile’at 16hours-3 days,16 hours-3 days,and 9 hours-4 days,respectively.The expression levels of key genes for defense enzyme synthesis pathway POD2,PPO1,PPO2,and SOD2were significantly higher than’Meile’after inoculation The content of SA and JA in’Huamei’rapidly increased after inoculation,and the expression levels of key synthesis pathway genes ET-SAM and SA-sa were overall higher than those in’Meile’.Disease progression related proteinsβ-1,3-GA at 15-60 hours after inoculation,the enzyme activity and gene expression of the synthesis pathway PR1-1 were significantly higher than those of’Meile’,The H2O2activity in’Huamei’is higher than that in’Meile’at 30hours-5 days.4.Analysis of phenolic secondary metabolites and pathway genes after inoculation showed that there were significant differences in the types and quantities of metabolites detected in the resistant variety’Huamei’compared to’Meile’at different time points after inoculation;Compared with’Meile’,’Huamei’synthesized phenolic acids such as p-dimer galloyl methyl ester,2,5-dihydroxybenzaldehyde,demethyl pilonolactone6-O-glucoside,salidroside and other substances significantly higher than’Meile’. |
