Kevison Romulo da Silva França, José Tomáz Ferreira Nunes, Mayra Machado de Medeiros Ferro, Mariote dos Santos Brito Netto, Sarah Jacqueline Cavalcanti da Silva, Iraildes Pereira Assunção, Gaus Silvestre de Andrade Lima, Gildemberg Amorim Leal‐Júnior
Fungi of the genus Colletotrichum exhibit broad ecological diversity, with species reported as endophytes as well as plant pathogens, reflecting the complexity of plant–fungus interactions. In Phaseolus lunatus , the presence of the endophytic Colletotrichum species may play a decisive role in determining cultivar resistance to anthracnose. This study aimed to identify endophytic Colletotrichum species associated with P. lunatus cultivars exhibiting contrasting responses to anthracnose, to assess their pathogenicity in their host of origin, and to investigate their antagonistic potential against C. truncatum . Eleven endophytic isolates obtained from aerial tissues of a resistant cultivar ‘G65’ and a susceptible cultivar ‘OVIC’ were analyzed. Species identification was performed using multilocus phylogenetic analyses using a concatenated alignment of act , apn2, APN2/MAT-IGS, gapdh , his3 , ITS, and tub2 markers. The isolates were identified as C. plurivorum , C. musicola , and C. chrysophilum , belonging to the C. orchidearum and C. gloeosporioides species complexes. Colletotrichum plurivorum was the most common species and predominated among isolates from the resistant cultivar. In pathogenicity assays on detached leaves, most isolates did not induce typical anthracnose symptoms, confirming their endophytic behavior; however, C. musicola caused mild symptoms in the susceptible cultivar. In both direct and indirect antagonism assays, all isolates inhibited the mycelial growth of C. truncatum , indicating that inhibition occurred even under conditions that allowed only volatile-mediated interactions. In general, these results indicate that endophytic Colletotrichum species were identified across different host genotypes, with C. plurivorum emerging as a potential source of bioactive compounds for the biological control of anthracnose in P. lunatus . • Multilocus phylogenetic analyses identified three Colletotrichum species associated with asymptomatic tissues of contrasting Phaseolus lunatus genotypes. • Endophytic community composition varied according to host genotype and anthracnose response. • Most isolates produced no visible symptoms in detached-leaf assays, whereas C. musicola and C. chrysophyllum induced small lesions in the susceptible genotype. • Endophytic isolates showed antagonistic activity against C. truncatum in direct and remote confrontation assays under in vitro conditions. • Isolates of C. plurivorum obtained from the resistant genotype showed greater antagonistic activity against C. truncatum.