Studies On In Vitro Screening Of Resistant Mutants And Physiological Resistance Of Eggplant To Verticillium Dahliae

In vitro screening of resistant mutants and Physiological disease resistance of eggplant Verticillium dahliae were studied with Verticillium dahliae toxin and tissueculture technology systematically . Verticillium dahliae toxin made the seedling of eggplant cause the same symptoms as that the pathogen infected. The happening of wilt symptoms was earlier and worse in susceptible varieties than that in resistant ones. The induction rates of NianMaoQie and MengQIe-4 cultured on the medium of MI (MS medium + lAAlmg/kg + NAA Img/kg + KT0.2mg/kg) were higher than that of ChiQie and BiJingZiYuan. The effects of induction in stem were better than that in hypocotyl and cotyledons. The induction rates of explant and callus of eggplant were inhibited by concentration of Verticillium dahliae toxin. Under the concentration of 15 %, the induction rate was no more than 30%. The concentration of 15% was considered as the selection pressure of resistant mutants of eggplant to Verticillium dahliae. The resistance of callus to Verticillium dahliae toxin could be improved by increasing the colony times and the concentration gradually. It was advisable to obtain a resistant mutant with step-by-step method. There was a significant positive correlation between the resistance level of varieties to Verticillium dahliae and the changes of eroxidase(POD),phenylanine ammonia lyase(PAL) and polyphenoloxidase(PPO) activities : the higher the resistance was , the stronger their activity was on leaf . Great difference of POD, PAL and PPO activities existed between resistant and susceptible cultivars after treatment as well.The Results also showed that the change of PAL and PPO activities in callus were similar to those of on leaf . Both of them increased rapidly at the beginning after treatment then decreased .As the concentration of Verticillium dahliae toxin increasing , the changes of the permeability of cells in callus and leaf were increasing continually . Therefore, the disease resistance of level of plants was faithfully expressed hi callus.