Differential responses of popcorn under Bipolaris maydis stress using Label Free Proteomics approach

In maize crops Southern Leaf Blight (SLB) is a severe disease caused by the fungus Bipolaris maydis (Y. Nisik & C. Miyake) leading to several losses in crop production. Unlike in maize, popcorn resistant varieties are not yet commercially available and this trait have been the subject of many popcorn breeding programs. The present study aimed to identify differentially accumulated proteins (DAPs) associated with resistance to B. maydis in two contrasting popcorn inbred lines using the comparative proteomic analysis. Forty-day old popcorn plants from resistant and susceptible inbred lines at the V4 growth stage were inoculated with B. maydis by spraying the conidium suspension. At four and ten days after inoculation, the morphological aspects of lesions in leaves were checked and the proteomic analysis was performed. Our results showed that the resistant inbred line exhibited minor foliar lesions in comparison with the SLB-susceptible genotype. In the genotype’s comparison, 644 DAPs were identified at 4 days and 613 at 10 days after B. maydis inoculation. Besides that, in resistant plants were identified DAPs upaccumulated related to response to stress, response to stimulus, photosynthesis, cellular growth, maintenance and detoxification process, which might be involved in plant response against the pathogen. It was identified proteins as salicylic acid-related and nucleotide-binding leucine-rich repeat that may be responsible to initiate a response to fungus in SBL-resistant inbred line. A differential response was identified in chloroplast proteins that is the main organelle involved in perception of the fungus to initiate a signalizing response. The changes in the proteomic profile in resistant inbred line may be effective in the response under B. maydis infection. This is the first work presenting the proteomic profile alteration under B. maydis inoculation and these findings may be useful for identifying candidate biomarkers in popcorn resistance to B. maydis being relevant for further researches on genetic breeding to develop resistant genotypes.