Mango is a globally vital tropical commercial fruit crop boasting a sizable industry and remarkable economic benefits. Nevertheless, mango leaves, abundant in carbohydrates, polyphenols and other nutrients, remain underdeveloped in comprehensive resource exploitation. First, comparative analysis of leaf phenotypic traits and nutritional quality at different developmental stages of the Guifei cultivar showed that mature leaves possessed significantly higher contents of soluble sugar, total polyphenols, and total flavonoids, as well as better comprehensive traits, indicating that the mature leaf stage is optimal for deep processing. Subsequent assays of 70 mango germplasms detected obvious differences in leaf phenotypic characteristics and nutritional quality among materials, with the coefficient of variation values ranging from 2.35% to 50.38%. Correlation analysis revealed significant intra-group correlations for leaf phenotypic indicators and antioxidant indicators, whereas the five basic nutritional indices were mutually independent. Cluster analysis classified the tested germplasms into four distinct groups with clear trait divergence and unique functional features. Five principal components were extracted from 11 leaf quantitative indices to construct a comprehensive evaluation system, which pinpointed elite accessions including Sri Lanka No.811, Nam Dok Mai, and Shuoshuai Mango, with Sri Lanka No.811 exhibiting the highest total polyphenol content. This study determines the optimal harvest period and elite germplasms for high-value utilization of mango leaves, facilitating special-purpose germplasm screening and targeted breeding.

Mango (Mangifera indica L.), a major tropical fruit crop, suffers severe anthracnose damage caused by Colletotrichum spp., and traditional chemical control has environmental and food safety risks, with plant-microbe interaction-based biological control as a sustainable alternative. However, the regulatory role of phyllosphere microbiota in the tripartite interactions among mango, beneficial microbes and Colletotrichum remains unclear. This study explored phyllosphere microbiota’s function in mango resistance to Colletotrichum and clarified the biocontrol mechanism of key beneficial isolates. We found Colletotrichum infection significantly reshaped mango leaf endophytic and epiphytic microbial communities, enriching Burkholderia, Acinetobacter, Bacillus and other dominant genera. We isolated a B. subtilis strain L-1 from the epiphytic microbiota that was 18-fold enriched in Colletotrichum-infected mango leaves. This strain exhibited potent antagonistic activity against Colletotrichum siamense with a relative inhibition rate of 82.10%, and delivered 79.77% biocontrol efficacy on mango leaves via two synergistic pathways: inhibiting pathogen spore germination and penetration by producing antimicrobial secreted metabolites and volatile organic compounds, and enhancing host disease resistance. Our findings advance the understanding of plant-phyllosphere microbiota-pathogen tripartite interactions and provide elite microbial resources for sustainable anthracnose management.