Objective Plant chitinase (CHi) is a pathogenesis-related protein that plays a crucial role in plant defense against fungi. This study aims to systematically characterize the CHi gene family in Momordica charantia and reveal its expression changes in response to Fusarium oxysporum infection.

Method Using Arabidopsis thaliana chitinase protein sequences as the query sequence, BLASTp alignment was performed in M. charantia genome. Identified CHi genes were characterized in terms of physicochemical properties, phylogenetic analysis, and gene structures. Additionally, RNA-seq analysis was conducted on root tissues of seedlings inoculated with F. oxysporum for 3 d to examine the expression profiles of CHi genes.

Result A total of 38 M. charantia CHi genes were identified, located on chromosomes 1, 3, 4, 5, 6, 8, and 10, respectively. Physicochemical analysis revealed that the members of the CHi gene family encode 233 to 879 aa, with molecular weights ranging from 25.83 to 95.43 kDa, isoelectric points between 4.62 and 9.78, instability indices from 22.25 to 96.54, and grand average of hydropathicity (GRAVY) from -0.893 to 0.104. Phylogenetic analysis classified them into five groups, with members within the same group showing high similarity in conserved domains. Analysis of the promoter region showed that TATA-box and CAAT-box elements were present in all CHi genes and were significantly more abundant than other cis-acting elements. Furthermore, the number of CHi genes showing up-regulated expression in the resistant cultivar 'K49' was significantly higher than that in the susceptible cultivar 'CP92' at three days after inoculation with F. oxysporum. Among these up-regulated genes, except for McCHi1 from the GH19 subfamily, the remaining 13 significantly upregulated genes all belonged to the GH18 subfamily.

Conclusion This study provides the first systematic identification and expression analysis of the CHi gene family in M. charantia under F. oxysporum infection. The findings indicate that up-regulated CHi genes are likely play a key role in the defense response against fusarium wilt, offering valuable insights for further research on disease resistance mechanisms and breeding applications.