Determination of physiological, biochemical and molecular parameters that can be used in the selection of plants resistant to Zymoseptoria tritici under dual stress conditions in wheat breeding

This study was carried out in greenhouses, climate chambers and laboratories of Harran University Faculty of Agriculture, Department of Plant Protection and Diyarbakır Agricultural Control Research Institute between 2020-2023. The performances of Nurkent wheat varieties, which are sensitive to Zymoseptoria tritici, and Ceyhan-99 wheat varieties, which are characterized as resistant, under NaCl stress were evaluated in seed, germination and post-germination development periods. Nurkent, which is evaluated as more sensitive to Z. tritici infection than Ceyhan-99, also responded more sensitively to NaCl stress than Ceyhan-99. In order to determine how different NaCl (0, 40, 75 and 155 mmol L-1) concentrations of Z. tritici affect the germination and seedling periods of susceptible Nurkent and resistant Ceyhan-99 wheat genotypes and how they affect the physiological and morphological development of the plants, data on root number, root length, root dry weight, root fresh weight, stem fresh weight, stem fresh weight, stem length, germination time and germination percentage index were examined. With increasing NaCl concentrations, germination time increased in both varieties, while all other parameters decreased. When the biochemical parameters of the pathogen were examined, it was seen that although it was stressed in 75 mmol L-1 and above NaCl conditions, which was shown by the increase in H2O2, MDA, proline, but the levels of destructive enzymes such as protease and laccase also increased and therefore the pathogen was active. The role of the separate and combined effects of Zymoseptoria tritici and NaCl (salt) stress on the defense system of Nurkent (susceptible) and Ceyhan-99 (resistant) varieties during the development period of Triticum aestivum (wheat) plants was evaluated physiologically (leaf area etc.) and biochemically on the 0th day, 7th day and 14th day, and the responses of the plants were revealed by measuring H2O2, MDA, protein, proline, Peroxidase, Superoxide dismutase, Catalase, Jasmonic acid, Salicylic acid, total phenol and PAL enzymes and metabolites and molecular parameters. Accordingly, H2O2 and MDA, which are accepted as stress metabolite criteria, increased in control plants depending on age, but showed a significant increase in plants exposed to stress. Wheat varieties exposed to combined stress responded by synthesizing stress metabolites at different NaCl concentrations, and it was determined that combined stress caused the accumulation of more stress metabolites, and it was determined that the varieties gave similar responses. It was determined that 26 different genes were expressed at different levels as a result of the combination of protein with pathogen in the susceptible Nurkent and resistant Ceyhan-99 wheat varieties. The responses of SOD genes were determined in both NaCl, pathogen and NaCl+pathogen conditions, and the responses of 7 genes (SOD1, SOD6, SOD8, SOD13, SOD16, SOD20 and SOD21) showing activity were revealed in NaCl, pathogen and NaCl+pathogen conditions. In this study, the stress caused by genes and metabolites in pathogen, NaCl and pathogen + NaCl conditions were tested on wheat varieties. It was determined that the marker enzymes, metabolites and genes and molecular analyses used here are important criteria in developing varieties against combined stress.