In this study Trichoderma harzianum strain A was isolated from the rhizosphere of an argan tree in southern Morocco. Trichoderma harzianum strain A had previously demonstrated a high antagonistic potential in vitro by direct confrontation and in vivo on wheat plants in pots under greenhouse conditions against Zymoseptoria tritici, the agent of septoria leaf blotch. In this study, the activity of filtrates prepared from the liquid culture of T. harzianum A alone and from the confrontation medium with two Z. tritici strains [G1-1 (durum wheat) and A5-1 (soft wheat)] on the inhibition of Z. tritici pycnidiospore germination was studied by nephelometry. The results of the antibiosis assay revealed that filtrate 0 (A in confrontation with G1-1) and F3 (A against A5-1) showed 95% of G1-1 and A5-1 pycnidiospore inhibition at 9/10 dilution of the undiluted filtrates after 4 days of incubation. To understand and explain the antifungal activity of these filtrates, the extraction and identification of secondary molecules of peptaibiotic nature secreted by T. harzianum A in the three studied filtrates were performed. According to the results of high-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses, 38 peptaibiotic molecules reported in the literature for their antifungal activity were identified in the different extracts at high concentrations (high peak intensities). These molecules are divided into nine groups, namely: Trichocryptin, Trichobrevin, Triochocryptin, Hypocompactin, Hyporodicin, Trichocompactin, Alamethicine, Trichoferin, and Trichokonin. It was also shown that the presence of the pathogen induces the production of peptaibols by the antagonistic strain of Trichoderma.

This study was carried out for the estimation of polyphenols (TP) and induction of oxidative enzymes polyphenol oxidase (PPO) and peroxidase (POD) in sunflower plants through seed immersion in agrochemicals of salicylic acid (SA) and water soluble chitosan (CH) in addition to a conidial suspension of Trichoderma harzianum and then analysis of plant content of carbohydrates and protein. The highest level of PPO 253.3 U ꞏ min ^–1 was detected in 50 ppm SA for 6 h. Next was T. harzianum when catalyzed PPO with 193.67 U ꞏ min ^–1. Peroxidase was substantially catalyzed in accordance with the increment of inducers. Sunflower roots induced TP with up to 4.88 mg ꞏ g ^–1 in plants treated with SA at 50 ppm for 6 h and then declined with an increasing SA dose. The total carbohydrate content in leaves of 320 mg ꞏ 100 g ^–1 was found in treatments of CH at 50 ppm for 6 h. In roots, a carbohydrate content of 500 mg ꞏ 100 g ^–1 was observed using CH 75 ppm for 6 h. Trichoderma harzianum remarkably increased proteins in leaves and roots by up to 25% compared to 16.9% in the control. These results suggest that inducing the plants’ own defense mechanism by applying salicylic acid and chitosan and bio-control of T. harzianum may offer alternative methods for controlling charcoal rot of sunflower due to the creation of defensive enzymes and could support plant vigor by enhancement of its protein and carbohydrate content.