Fungos endofíticos de Paspalum: potencial de promoção de crescimento vegetal, biocontrole e solubilização de rochas fosfatadas

Abstract

The prospecting of endophytic fungi with biotechnological potential has emerged as a strategy for developing microbial inoculants capable of reducing dependence on chemical fertilizers and pesticides in agriculture. In this context, this study evaluated the performance of endophytic fungi isolated from Paspalum—a genus of perennial grasses widely distributed throughout the Americas and recognized for its high resilience and forage importance—with a focus on plant growth promotion, inorganic phosphorus solubilization, and the biocontrol of Colletotrichum sp., a phytopathogenic fungus that causes anthracnose. Three isolates were selected for characterization from a collection of 385 endophytic isolates: PN F 4-21 (Talaromyces sp.), PN R 3-1 (unidentified), and PN F 9-7 (Penicillium sp.). The in planta assays were conducted with Paspalum regnellii under greenhouse conditions, allowing simultaneous evaluation of growth promotion and biocontrol. In parallel, the in vitro analyses included the solubilization of four phosphate sources (Araxá and Bayóvar phosphate rocks, triple superphosphate, and calcium phosphate), the characterization of hydrolytic enzymes, and a qualitative test for potassium solubilization. The production of IAA, flavonoids, and acid phosphatase activity was determined through solid-state fermentation. The isolate PN F 4-21 promoted increases in vegetative growth, greater biomass accumulation, and reduced anthracnose severity in P. regnellii, in addition to exhibiting high acid phosphatase activity and expressive solubilization of calcium phosphate. The isolate PN R 3-1 (unidentified) did not yield positive responses in plant development but showed high efficiency in phosphorus solubilization across all evaluated sources and presented hydrolytic activity, including pectinases and protease. The isolate PN F 9-7 exhibited relevant phosphorus solubilization for Araxá and Bayóvar phosphate rocks and calcium phosphate, as well as the highest levels of IAA and flavonoids among the isolates, although without effects on plant growth under the evaluated conditions. The results demonstrate the diversity among Paspalum endophytic isolates and reinforce their potential as a biotechnological basis for developing microbial inoculants applicable to sustainable agriculture.