Effect of Fusarium wilt on proteinaceous content and pathogenesis-related proteins in Cucumis melo

In the present study, five Cucumis melo genotypes (Resistant-Wild melon & Snap melon; Moderate- Hara madhu; Susceptible- Punjab sarda & Punjab sunehri) were screened for determining proteinaceous alterations against Fusarium oxysporum f. sp. melonis (FOM) infestation. Biochemicals viz. total soluble proteins, crude proteins, and pathogenesis related (PR) proteins (chitinase and glucanase enzyme activities) were evaluated in root tissues at 7, 14, and 21 days after inoculation (DAI) of FOM. Significant differences were observed between resistant, moderate and susceptible genotypes w.r.t. proteinaceous content and PR protein activities with the highest content/activities at 14th DAI in resistant genotypes. Further, the gene expression analysis of PR gene via qRT-PCR also revealed the significant and upregulated response in the resistant genotype at 14 DAI, hence validating the biochemical output. The electrophoretic analysis using SDS-PAGE showed that the 40 kDa protein band was absent in the resistant genotype i.e., in wild melon under both control (7th, 14th & 21st DAI) as well as in treatment (7th & 14th DAI). However, it was present on the 21st DAI in wild melon at the inoculated stage and in all other genotypes at all stages and under both treatments. The absence of this protein in the resistant genotype at the 7th and 14th DAI suggests a possible pathway to resistance. Further detailed and targeted exploration of this PR protein could help breeders in the development of FOM-resistant C. melo varieties.