Researches on obtaining resistant lines toVerticillium wilt (Verticillium dahliae Kleb.) via InVitro selection in cotton (Gossypium hirsutum L.)

Cotton is the raw material for many different industries, the main economical sectors of our country as textile industry. Cotton has important effects for socialeconomics in our country and all around the world as we consider about the employment that cotton farming and industries of cotton provides. The most important disease in cotton plant is wilt disease which is the consequence of Verticillium dahliae Kleb., the fungal pathogen which can happen at any period of vegetation. This disease which has a large hosting string causes important economical loss in the world and also in our country. Because of this disease, producers can not get enough output per unit area and the leaf quality rates are affected negatively. In actual system, desirable success haven't been obtained yet in the struggle with the disease. The resistance lines are being used for this disease which does not have any chemical struggles. Although the resistance genes are known for Verticillium wilt, to use this in classic breeding studies is very hard, expensive and also takes long time. The use of biotechnological methods is also important in plant breeding in terms of saving time and the identification of correct individual members in selection stage. In this project, the use of mutation which is important for the emergence of somaclonal variation in in vitro selection studies and determination of effective mutation dose, also it is aimed to reveal the effects of the Verticillium dahliae Kleb. culture filtrate applications on the physiological development and the biochemical component of cotton(Gossypium hirsutum L.) calli. For this purpose, the potentials of culture filtrate and mutajen applications for obtaining resistant plants were determined by using Verticillium wilt sensitive (NP Özbek 100) and tolerant (Carmen) cotton varieties. The effects of four different gamma radiation doses (100, 200, 300 and 400 Gy) on seed germination rate, seedling length and root length were investigated. On the 7th day of germination treatment, the effective mutation dose was determined as 300 Gy, which is the most limited germination rate, seedling length and root length compared to the control group. Three different doses (25%, 50%, 75%) of the culture filtrates obtained from the defoliating (PYDV 6) and nondefoliating (NPAE Vd11) pathotypes of Verticillium dahliae were added to callus media. The sensibilities of calli to the disease factor were determined. When the effect of culture filtrate applications on callus was examined, it was seen that fungal culture filtrate and dose PYDV6 %75 which caused the most anthocyanin and brown callus formation among the pathotypes on the 28th day of the experiment and the callus weight decreased at the same dose. The effect of 75% culture filtrate of PYDV6 pathotype on protein, chlorophyll, hydrogen peroxide, catalase and peroxidase amounts of both cotton cultivars were investigated. It was determined that chlorophyll a, chlorophyll b, total chlorophyll, total carotenoid amounts decreased with the application of culture filtrate in the groups with and without mutation and Carmen cultivar was most affected among the varieties. In the groups without mutation, the amount of catalase increased by 138% and the mutation application increased by 165% with culture filtrate on Carmen cultivar. In the NP Özbek 100 cultivar, the amount of catalase in the same groups decreased by 34% and 48% respectively. In groups without mutation, peroxidase amount was 8 times higher in Carmen cultivars and 4 times more in NP Özbek-100 cultivars with culture filtrate. In the mutation groups, this ratio was 2.5 and 2 times for the same varieties, respectively.