Antagonistic potential of Trichoderma hamatum against Alternaria porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis

Alternaria porri causing purple blotch disease of onion is a destructive phytopathogen which causes severe loss in productivity. The present study aimed to unravel the antagonistic potential and efficacy of volatile organic compounds produced by various Trichoderma spp. against A. porri causing purple blotch disease of onion through Gas chromatography-mass spectrometry (GCMS) analysis. Ten isolates of Trichoderma species were isolated from the rhizospheric soil of healthy onion plants. Upon paired plate technique, the in vitro efficacy of ten Trichoderma isolates were tested against virulent isolate of Alternaria porri isolated from purple blotch disease infected onion plants. The Trichoderma isolate TIM2 showed 76.29 per cent inhibition on mycelial growth of pathogen. The effective Trichoderma isolate was identified as Trichoderma hamatum through the analysis of the rDNA of internal transcribed spacers (ITS) region and it was subjected to GC-MS analysis.  The result of GCMS analysis indicated the highest peak area and retention time with major antimicrobial bioactive compounds like Tetradecane, 2,6,10-trimethy (20.327), (1.22) and Dodecane, 2-cyclohexyl (20.079), (2.14), Heptadecane (21.222), (9.50), Octadecane (22.379), (3.58), Eicosane, 9-cyclohexyl (22.578), (1.84), 2-Propenoic acid, pentadecyl ester (23.400), (10.37), 2,6,10,14-tetramethyl (23.567), (10.37), Eicosane (27.311), (2.34), Hexadecanoic acid, methyl ester (27.918), (4.43), n-Hexadecanoic acid (29.156), (3.59) and  Tetrapentacontane, 1,54-dibromo (31.906), (3.33). These bioactive compounds identified through GCMS analysis from the crude extracts of Trichoderma hamatum exhibited a stronger antifungal activity against A. porri. Hence the application of T. hamatum for the management of purple blotch disease highly supress growth of the pathogen and reduce the disease incidence.    

Antifungal activity of Trichoderma atroviride against Fusarium oxysporum.f.sp.lycopersici causing wilt disease of tomato

Fusarium oxysporum f. sp. lycopersici causing tropical wilt of tomato is a destructive phytopathogen. To study bio efficacy of fungal bio agents, fifteen isolates of Trichoderma species were isolated from rhizosphere soil of healthy tomato plants. Among the isolates, TA12 showed higher antagonistic efficacy against the pathogen. Upon analysis of the rDNA of internal transcribed spacers (ITS) and molecular data, the isolate was identified as Trichoderma atroviride. The in vitro antagonistic assessment indicated that the T. atroviride isolate caused significant inhibition of F. oxysporum f. sp. lycopersici. Trichoderma atroviride (TA12) showed antagonistic activity against F. oxysporum with mycelial inhibition of 71.25%. The culture filtrates of Trichoderma atroviride exhibited its antifungal activity against F. oxysporum with a suppression of 77.77%. Moreover, the ethyl acetate extracts of T. atroviride TA12 showed the highest antifungal potency against F. oxysporum f. sp. lycopersici. The main bioactive constituents of T. atroviride were 6-pentyl - 2H-pyran-2-one, quinoline, phenol, 2-(6-hydrazino-3-pyridazinyl) and heptadecane. In conclusion, the isolate TA12 could be exploited to develop an effective biocontrol management practice for combating Fusarium wilt disease of Fusarium oxysporum f.sp. lycopersici in tomato

Antifungal activity of Trichoderma atroviride against Fusarium oxysporum.f.sp.lycopersici causing wilt disease of tomato

Fusarium oxysporum f. sp. lycopersici causing tropical wilt of tomato is a destructive phytopathogen. To study bio efficacy of fungal bio agents, fifteen isolates of Trichoderma species were isolated from rhizosphere soil of healthy tomato plants. Among the isolates, TA12 showed higher antagonistic efficacy against the pathogen. Upon analysis of the rDNA of internal transcribed spacers (ITS) and molecular data, the isolate was identified as Trichoderma atroviride. The in vitro antagonistic assessment indicated that the T. atroviride isolate caused significant inhibition of F. oxysporum f. sp. lycopersici. Trichoderma atroviride (TA12) showed antagonistic activity against F. oxysporum with mycelial inhibition of 71.25%. The culture filtrates of Trichoderma atroviride exhibited its antifungal activity against F. oxysporum with a suppression of 77.77%. Moreover, the ethyl acetate extracts of T. atroviride TA12 showed the highest antifungal potency against F. oxysporum f. sp. lycopersici. The main bioactive constituents of T. atroviride were 6-pentyl - 2H-pyran-2-one, quinoline, phenol, 2-(6-hydrazino-3-pyridazinyl) and heptadecane. In conclusion, the isolate TA12 could be exploited to develop an effective biocontrol management practice for combating Fusarium wilt disease of Fusarium oxysporum f.sp. lycopersici in tomato