Isolamento de fungos endofíticos e estudo metabolômico de espécies de Coffea resistentes ao bicho-mineiro

Abstract

The coffee leaf miner (Leucoptera coffeella) is one of the most significant pests affecting coffee cultivation, particularly in cultivars of Coffea arabica, which are highly susceptible to its attack. In contrast, wild species such as C. racemosa and C. stenophylla have emerged as promising sources of natural resistance. This study investigated the chemical and microbial mechanisms associated with resistance to the coffee leaf miner in these species, with a focus on bioactive compounds and the diversity of endophytic fungi found in the leaves of resistant Coffea genotypes. In a comparative metabolomic analysis involving Coffea arabica cv. Catuaí Amarelo IAC 62, C. racemosa, C. stenophylla, and the experimental resistant hybrid IAC 1059 (derived from a cross between C. arabica and C. racemosa), specific chemical signatures associated with resistance were identified, including the accumulation of malic acid, succinic acid, isotreonic acid, and quinic acid. These compounds are broadly linked to defense mechanisms such as cellular acidification, metal ion chelation, and oxidative stress signaling. The resistant hybrid displayed an intermediate metabolomic profile, reflecting the partial inheritance of resistance traits from C. racemosa, notably with increased levels of isotreonic acid, glycolic acid, pentanoic acid, and maltotriose. In parallel, 65 endophytic fungal isolates were obtained from the leaves of C. racemosa and C. stenophylla. Among them, one isolate identified as belonging to the genus Colletotrichum demonstrated entomopathogenic potential, causing 70% mortality in Tenebrio molitor larvae. This isolate also produced chitinase in a medium containing colloidal chitin, an enzyme potentially involved in insect cuticle degradation. The findings of this study highlight that resistance to the coffee leaf miner in Coffea species involves a complex interplay of chemical and biological factors, and that both defensive metabolites and endophytic fungi may play complementary roles in this process. These results reinforce the importance of leveraging Coffea biodiversity in developing sustainable pest management strategies for coffee cultivation.