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Microbial elicitors to induce immunity for plant disease control in chilli and tomato
Author(s)
Date Issued
March 1, 2014
Type
Book Chapter
Abstract
The induced immunity in long cayenne pepper in terms of phytoalexin production using microbial elicitors as chaetoglobosin C from Chaetomium globosum, chaetomanone A from Chaetomium lucknowense, and trichotoxin A50 from Trichoderma harzianum PC01 was investigated in pot experiments. Stem inoculation of chilli plants with Colletotrichum capsici isolate C208 resulted in necrosis and accumulation of capsidiol, a phytoalexin. Stem inoculation of chilli plants resulted in different degrees of sensitivity to C. capsici, expressed as necrosis along the stems. The microbial elicitors chaetoglobosin C, chaetomanone A, and trichotoxin A50 induced an immunity response against C. capsici. Qualitative analysis of capsidiol accumulation in the upper part of the chilli plant was detected by thin-layer chromatography and showed that capsidiol had accumulated in the chilli plant at 5 and 10 days after treatment with the microbial elicitors, whereas no capsidiol was detected in the noninoculated and untreated plants. Chilli cultivation of long cayenne pepper in vivo was conducted by spraying chaetoglobosin C, chaetomanone A, and trichotoxin A50, and the findings were compared with cultivation using a chemical fungicide (difenoconazole). The results showed that application of each microbial elicitor reduced disease incidence by 42-55 % when compared with an inoculated control, whereas difenoconazole reduced disease incidence by 33 %. Additionally, the yield increased by 47-55 % when compared with the yield for the inoculated control. Chilli cultivation of long cayenne pepper in vivo using the biological fungicides Bio-CG from C. globosum N0802, Bio-CLT from C. lucknowense CLT, and Bio-T from T. harzianum PC01 resulted in reduction of disease incidence by 39-55 % when compared with the inoculated control, whereas difenoconazole reduced disease incidence by 33 %. Moreover, treatment with Bio-CG, Bio-CLT, and Bio-T increased the yield by 39-53 % when compared with yield for the inoculated control. Moreover, the bioactive compounds chaetoglobosin C, chaetomanone A, and trichotoxin A50 were used as microbial elicitors to elicit α-tomatine in tomato. α-Tomatine was detected by high-performance liquid chromatography after treatment with the bioactive compounds. Chaetoglobosin C, chaetomanone A, and trichotoxin A50 were sprayed onto inoculated tomato seedling variety Sida inoculated with Fusarium oxysporum f. sp. lycopersici NKSC01, and plant disease immunity and quantity of α-tomatine were assessed. The results revealed that plant disease immunity of tomato seedlings treated with chaetoglobosin C, chaetomanone A, and trichotoxin A50 at a concentration of 50 μg/ml after 10 days was 44.97, 35.18, and 39.43 %, respectively, whereas tomato seedlings treated with prochloraz that showed plant disease immunity of 29.95 %. The stems and leaves of tomato were extracted and spotted on thin-layer chromatography paper and produced a green spot with a retention factor of 0.23, the same as for a spot of standard α-tomatine. Tomato extracts were analyzed for α-tomatine by high-performance liquid chromatography. The α-tomatine quantification data were analyzed using a linear regression curve. Tomato treated with chaetoglobosin C, chaetomanone A, and trichotoxin A50 at 15 days expressed α-tomatine at levels of 207.87, 254.25, and 205.04 μg/g, levels which are significantly higher than those resulting from prochloraz and inoculation treatments, for which the quantities of α-tomatine were 131.56 and 77.46 μg/g, respectively. It is shown that the induction of α-tomatine by chaetoglobosin C, chaetomanone A, and trichotoxin A50 in tomato plants implies disease immunity against fusarium wilt of tomato variety Sida through phytoalexin production. The bioactive compounds were tested for their efficacies to control tomato wilt in vivo. The results revealed that all the bioactive compounds at concentrations of 10, 50, and 100 μg/ml could induce plant disease immunity in tomato between 53.80 and 65.15 %, which is significantly higher than the plant disease immunity induced by prochloraz, which was 26.73 %.
Citation
Basic and Applied Aspects of Biopesticides, 9788132218777, 99-125, 2014