ارزیابی تغییرات سیستم دفاعی غیرآنزیمی ارقام پنبه در واکنش به بیماری پژمردگی ورتیسیلیومی

Among the responses of plants to stress, increasing proline and producing secondary metabolites include phenolic compounds tannins, flavonols and phenols in leaves and stems, which are involved in plant resistance against pathogens. This experiment was conducted to determine the effect of the disease on the physiological characteristics of cotton cultivars during the two years of 2021-2022 and in a factorial format in the form of a completely randomized design in three replications in the greenhouse of the Research Center for Agricultural Education and Natural Resources in Razavi Khorasan. Under the controlled conditions of the greenhouse, the seeds of three cultivars Varamin (susceptible), Bakhtegan (tolerant) and Thermos 14 (resistant) were grown in pots containing sterile soil. At this stage, the amount of proline, soluble carbohydrates and total phenol was evaluated at different times after inoculation with the pathogenic fungus. All traits measured during two years were compared using SAS 9.1 statistical software, analysis of variance and Duncan's test. The standard isolate of Verticillium dahliae fungus was prepared from the Iranian Plant Medicine Research Institute. Inoculation was done 20 days after cultivation at the 6-8 leaf stage by stem wound method and with mushroom spore suspension with a concentration of 106 conidia per ml. The control treatment was only inoculated with distilled water without mushroom spore suspension. The results showed that the tested cultivars had a significant difference in terms of proline content, soluble carbohydrates content and total phenol content at the probability level of 1% Comparison of the average of the above traits indicates that the cotton plants inoculated with Verticillium wilt pathogenic fungus had more proline, soluble carbohydrates and phenol content than the control or control plants (no infection with the fungus). The results of the comparison of the mean interaction effect of cultivar × pollution × time showed that under the conditions of pollution, the amount of proline increases over time. Its highest amount is in 12 days after infection of cotton plants with Verticillium fungus. The highest value at this time is related to Thermos 14 and Bakhtegan cultivars, respectively. The amount of soluble carbohydrates gradually increased after inoculation of cotton plants with Verticillium wilt fungus, so that it reached the highest value on the 15th day after infection. The highest amount was related to Thermos 14 and Bakhtegan respectively. The amount of phenol was the highest in 3 days after inoculation of cotton plants with fungus and then it decreased. At this time, the highest amount of phenol was related to Thermos 14 and Bakhtegan cultivars, respectively. In summary, changes in the levels of proline, sugar (TSS) and phenol in cotton leaves caused by infection with V. dahliae were clearly consistent with the effects of Verticillium wilt.