Trichoderma harzianum isolate AKH-5 enhances defense response in Cajanus cajan (L.) millsp. against Fusarium oxysporum f. sp. udum and promotes plant growth
Anil Hugar, Sreenivasa Nayaka
Abstract
This study investigates the integrated role of Trichoderma harzianum isolate AKH-5 as a plant growth-promoting and biocontrol agent against Fusarium oxysporum f. sp. udum , the causative agent of wilt in Cajanus cajan (L.) Millsp. (pigeon pea). AKH-5 significantly inhibited fungal mycelial growth in vitro (91.73 %), with SEM analysis revealing pathogen hyphal damage. Chemical profiling (GC–MS and FTIR) identified functional groups and metabolites-such as alcohols, long-chain esters, sterols, and cyclic sulfur- associated with antifungal activity and plant health enhancement. In addition to volatile and soluble bioactives, AKH-5 produced IAA, siderophore, ammonia, ACC deaminase, and hydrolytic enzymes (e.g., amylase, gelatinase, chitinase, cellulase, glucanase) and oxidative enzyme (catalase), confirming its growth-promoting attributes. Hypersensitivity assays validated its non-pathogenic nature. A talc-based AKH-5 formulation improved seed germination ( 93.21 ± 0.33 %) and vigour index ( 1202), while greenhouse trials confirmed enhanced seedling growth, chlorophyll content, and reduced disease severity. These findings position AKH-5 as a multifunctional bioinoculant, offering a sustainable solution for enhancing crop productivity and managing soil-borne diseases. Schematic Overview of Trichoderma harzianum AKH-5 for Biocontrol Validation and Metabolic Characterization • Trichoderma harzianum AKH-5 exhibits strong antifungal activity against F. oxysporum with > 90 % mycelial inhibition. • Methanolic extract contain bioactive compounds that promote plant growth and pathogen suppression. • AKH-5 enhances seed germination, chlorophyll content, and seedling vigour under pathogen stress. • Formulated AKH-5 functions as an effective biocontrol agent and biofertilizer for sustainable agriculture.