| Sugarcane is an important industrial crop,cultivated in more than 90 countries including China.Disease is the main factor in the decline of sugarcane yield and sugar content.In sugarcane planting areas,smut has become an important disease in the world,and the prevalence rate is increasing year by year.If the infection is serious,it can cause 20%-50%loss in sugarcane production.Currently,the most economic and effective measures of controlling smut is replacing susceptible cultivars with resistant cultivars.However,the mechanism of sugarcane resistance to smut is still poorly understood.In this experiment,the smut-resistant variety GT29 and the smut-susceptible variety Yacheng71-374 were used,and they were inoculated with the teliospore suspension of smut pathogen by dipping method while the control group was treated with sterile water.After inoculation for 30 days,60 days,90 days and 180 days,respectively,the changes of plant height,fresh weight,leaf area and chlorophyll content were measured.and the activities of chitinase,?-1,3-glucanase and catalase activity,and the contents of auxin,cytokinin and ethylene in leaves were determined.Proteomics analysis was done using iTRAQ technology to detect differentially expressed proteins at 180 days after inoculation.The results were as follows.1.By comparing the changes in plant height,fresh weight,leaf area and chlorophyll content after smut infection,we found that the plant height was higher than the control at the early stage of disease development(30 days,60 days),but the fresh weight of the plant was not significantly higher than the control,and the disease infected plants grew faster but slender.The plant height and fresh weight were significantly lower than control at the late stage of the disease development.The leaf area decreased after infection,and Yacheng 71-374 showed the more significant difference.However,there was no significant correlation between the chlorophyll content and smut disease.2.During the whole infection period,the activities of chitinase and?-1.3-glucanasc,and the contents of auxin and cytokinin decreased gradually,but the activity of catalase increased.It is possible that the resistance mechanisms of sugarcane to smut are different at different stages.And the defense mechanisms of susceptible and resistant varieties may be different.3.Sugarcane leaf samples were taken at 180 days after smut pathogen inoculation for proteomic analysis by useing iTRAQ technique.The results showed that there were 1429 proteins with quantitative information in GT29,including 290 differentially expressed proteins with 153 up-regulated and 137 down-regulated,while there are 1576 proteins with quantitative information in Yacheng 71-374,including 125 differentially expressed proteins with 55 up-regulated and 70 down-regulated.The number of differentially expressed proteins in the resistant variety GT29 is higher than that in the susceptible variety Yacheng71-374,and GT294.enriched more metabolic pathways in KEGG,indicating that the immunomodulatory mechanism of the resistant variety may be more complicated,and the regulatory network involved in response is broader.Through the analysis of photosynthesis,antioxidant system,calcium signal,phenylpropane metabolism,hormone related differential expression protein,it was found that the photosynthesis pathway,POD.ABA,calcium signal pathway related protein were up-regulated in both sugarcane varieties.The up-regulated expression protein was more in GT29 than Yacheng 71-37,which may be involved in the response to smut in the later stage of sugarcane.Phenylpropanoid metabolic pathway and some enzymes(GPX,APX,SOD,GST,CAT)and hormones(IAA,ETH,GA)were not found to be involved in the disease resistance process of sugarcane in this experiment. |
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