A serious collar and rhizome rot disease of banana was observed in the north region of Maharashtra state in post rainy season. The disease was caused by the bacterial strains of Erwinia chrysanthemi pv. paradisiaca identified and characterized by morphological, physiological, biochemical and pathogenicity tests. The infection occurred on new banana plantation of one month old in poorly drained soil. In post rainy season, banana plantations of 8 to 10 weeks were found severely infected. E. chrysanthemi pv. paradisiaca produced soft rot symptom onhealthy banana rhizomes within three weeks. Two strains were isolated from the collar and rhizome rotted diseased samples which were similar in morphological, physiological and biochemical characteristics, however they differed in the virulence aggressiveness to cause the disease in banana. Strain II caused soft rot symptoms within 19 days, however strain I produced it within 23 days of inoculation with suspension of 3×108 CFU ml-1. The result of this study revealed that strain II was more aggressive as compared to strain I of E. chrysanthemi pv. paradisiaca.
Background: Resistance Inducing Chemicals (RIC) viz., Salicylic Acid (SA), $-aminobutyric acid (BABA), chitosan (CHT) and 2, 6-dichloroisonicotinic acid (INA) are known to play an important role in induction of resistance by increasing the activity of PR-proteins. Therefore the study was done to test these RIC's for accumulation of PR-proteins in tomato plant to confer resistance against Alternaria blight disease. Methods: The activity of PR-proteins viz., chitinase and $ 1,3-glucanase in tomato leaves were measured in response to treatment of these RIC's at different concentrations as seed dip treatment for 8 h, seedling dip treatment for 2 h and seed+seedling treatment. The RIC treated plants were challenged inoculated with Alternaria alternata, a tomato leaf blight pathogen at 10 days interval from germination and observed for disease development. Chitinases and $ 1,3-glucanase activity was determined spectronically by quantifying the release of mg of N-acetylglucosamine and of glucose, respectively at 30 days of RIC treatment as the persistence of resistance induced by RIC was up to 50 days. Results: Maximum activity of chitinase and $ 1,3-glucanase was observed in seed+seedling treatment with BABA at 15 mM concentration and the increase in chitinase and $ 1,3-glucanase activity was 32.00 and 56.59% more, respectively over control and was followed by treatment with salicylic acid at 1.5 mM concentration. Conclusion: The application of RIC SA and BABA elicits the increased activity of PR-proteins viz., chitinase and $ 1,3-glucanase which inhibit the process of pathogenesis in susceptible tomato cultivars to exhibit the resistance.
Chemical elicitors, namely salicylic acid (SA), β-amino butyric acid (BABA), chitosan (CHT) and 2,6-dicholoroisonicotinic acid (INA), are known to play a role in the induction of plant resistance to pathogens by increasing the activity of enzymes of phenolic synthesis pathways such as peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase. These chemical elicitors applied to tomato as an 8 h seed treatment, 2 h seedling treatment and seed plus seedling treatment increased the activity of peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase. The highest increase in peroxidase and phenyl alanine ammonia lyase activity was induced by the seed plus seedling treatment with 15 mM β-amino butyric acid. The increase in these enzyme activities was 70.5% and 39.3% higher, respectively, over control, whereas the highest increase in polyphenol oxidase activity was induced by the seed plus seedling treatment with 1.5 mM salicylic acid. Polyphenol oxidase activity increased 137.9% compared to the non-treated control. Similarly, seed treatment as well as seedling treatment with the elicitors particularly salicylic acid, β-amino butyric acid and chitosan elicited increased activity of peroxidase, polyphenol oxidase and phenyl alanine ammonia lyase of the phenolic syntheses pathways, which are known to be the basic components of the resistance induction mechanism.
Phytochemicals viz. soluble protein, reducing sugar and phenols were quantified from tomato (Solanum lycopersicon) leaves after application of resistance inducing chemicals viz. salicylic acid, β-aminobutyric acid, chitosan and 2,6- dichloroisonicotinic acid as 8 hr seed dip treatment or 2 hr seedling dip treatment or both treatment to study their effect on induction of resistance and inhibition of growth of pathogen. Soluble proteins and phenols were found maximum due to seed+seedling treatment of salicylic acid @ 1.5 mM concentration with 76.90 per cent and 102.68 per cent increase over control whereas reducing sugar was maximum for seed+seedling treatment of β-aminobutyric acid @ 15.0 mM concentration with 61.38 per cent increase over control. The increased level of protein quantity had no effect on inhibition of Alternaria alternata growth, whereas the increased quantity of sugar inhibited the average growth of Alternaria up to 19.39 per cent. Among phenolic compounds catechol and the cinnamic acid (formed in shikimic acid pathway of phenol biosynthesis) was inhibitory to the A. alternata whereas tannic acid hadsome effect on inhibition of Alternaria growth (13.84 % fungal growth inhibition). The increased level of sugar+phenol tested against the pathogen completely inhibited the growth of Alternaria fungus. Thus, the increased level of reducing sugar and phenol in tomato leaves due to the application of resistance inducing chemicals seemsto be inhibitory to the pathogens multiplication and pathogenesis.
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