Comprehensive Characterization and Screening of Different Trichoderma Isolates as Plant Growth Promoters: Insight to Metal Solubilization, Enzymatic Activity, and Antagonistic Effect

Abstract The present study aimed to isolate a Trichoderma species with dual action as a plant growth promoter in conjunction with antagonistic activity against the plant pathogen Colletotrichum lagenarium. Using internal transcribed spacer (ITS) sequences and inter simple sequence repeat markers (ISSR), eight strains of Trichoderma were identified, and their diversity was studied. In addition, some plant growth promoters such as indole acetic acid (IAA) and element solubilization were evaluated. Moreover, the activity of amylase, pectinase, cellulase, and chitinase was studied in the isolated species. Results showed that Trichoderma viride (T27) and Trichoderma atrobrunneum (T40) produced the highest IAA (80.36, 61.39 µg/mL), respectively and K solubilization efficiency (KE) (12.2 and 14.4, respectively). In contrast, Trichoderma afroharzianum (T31) and Trichoderma atrobrunneum (T40) had the highest zinc (Zn) solubilizer (7.1 and 7.2 cm), respectively. Strains T. viride (T27) and T. atrobrunneum (T41) showed the highest antagonistic activity against anthracnose fungi; therefore, they were examined under scanning electron microscopy. The SDS-PAGE protein pattern and its antigenicity analysis ranged between 40 and 180 kDa. The results of SDS-PAGE indicated that with chitin, both T27 and T40 presented different bands in their protein profile compared to the control (without chitin). The results suggest that T. viride (T27) and T. atrobrunneum (T40) could be used as eco-friendly bio-fungicides with a high potential plant growth promoter production.