| چکیده انگلیسی مقاله |
Extended Abstract
Introduction and Objectives: Wheat is the most important crop in many parts of the world, which has the largest cultivated area. As much as 30% of all grains produced in the country belong to wheat and it is known as the main food of half of the world's people. At the same time, environmental stresses, including biological stresses, have been one of the most important factors in reducing wheat yield in recent years. Despite many efforts, fungal diseases continue to attack the performance of this valuable grain. Powdery mildew (Blumeria graminis f.sp. tritici) is one of the important diseases of wheat that causes great losses to wheat production every year. On the other hand, the resistance of resistant genotypes in wheat is not constant over time, and the resistance of almost all resistance genes that are commonly used in the world has been broken by new pathogenic strains of powdery mildew. Because research has shown that the high pressure imposed by resistance genes on disease-causing populations has caused the rapid evolution of new pathogenic races and, as a result, the loss of resistance. For this reason, the identification of resistant genotypes has always been of interest to breeders all over the world, and the identification and exploitation of powdery mildew resistance genes in wheat breeding programs is a constant challenge for wheat breeders. For this reason, one of the most effective and logical methods of controlling this disease, which is most compatible with the environment and sustainable agriculture, is the identification and production of resistant cultivars.
Materials and Methods: In the present study, the number of 32 different bread wheat genotypes (Triticum aestivum L.) available in the Genetics Research Department and National Plant Gene Bank of Iran, Seedling and Seed Breeding Research Institute, exposed to 10 different pathotypes (Maghan 1, Maghan 2, Maghan 3, Maghan 4, Mughan 5, Gorgan 1, Gorgan 2, Sari 1, Sari 2 and Gonbad) of this mushroom were placed and their resistance level was investigated in the two-leaf stage under greenhouse conditions. The investigated pathotypes of powdery mildew, which were collected from disease-prone areas of the country, included five pathotypes from Mughan, two pathotypes from Gorgan, two pathotypes from Sari and one pathotype from Gonbedkavus. Propagation of the disease isolates was carried out on the sensitive Bolani variety, which lacks the Pm gene. Genotypes were inoculated by single cloned isolates by rubbing method and one week after inoculation, the reaction of differential cultivars towards the disease was done based on a scale of 0 to 4 according to Mains and Dietz method. Based on this scale, pollution type zero, one and two are in the resistant group and pollution type three and four are in the sensitive group. In this research, the Bolani variety was considered as a sensitive control to powdery mildew disease.
Results: The results showed that among the 10 powdery mildew pathotypes collected from important contamination centers in the country, the examined genotypes showed the highest resistance to the Mughan5 pathotype. Genotypes TN127, TN79, TN7, TN180 and TN72 showed the highest resistance to 10 pathotypes on average. In total, the comparison of different powdery mildew pathotypes showed that Mughan5 pathotype showed the lowest pathogenicity and Sari1 showed the highest. In addition, the correlation between pathotypes was done in order to identify pathotypes with similar pathogenic power, which showed that the Mughan5 pathotype showed the lowest correlation with other pathotypes, which probably uses a different mechanism for pathogenicity. Also, the highest significant correlation was observed between Mughan2 with Mughan3 (0.87) and Gorgan2 (0.81), which indicates the similarity of the pathogenic mechanism in these three pathotypes. On the other hand, the results of the cluster analysis divided the genotypes into two separate groups in terms of resistance to powdery mildew, and many of the investigated genotypes were included in the susceptible Bolani cultivar group. In addition, cluster analysis for powdery mildew pathotypes showed that Mughan5 pathotype was in one group and the rest of the pathotypes were in another group. Bi-plot and three-dimensional analysis based on the analysis data into principal components for the first and second components (87.95% of the total variance changes) showed that the Moghan5 pathotype has a lower correlation with other pathotypes. The negative side of the first component as well as the negative side of the second component shows the resistance of the genotypes. So that resistant genotypes were placed in area 1.
Conclusion: The genotypes examined in this research have not been evaluated for resistance to powdery mildew. Therefore, sources of resistance identified in this way are reported for the first time. In general, a potential variation was observed among genotypes with respect to different pathotypes. In terms of pathogenicity, among the examined pathotypes, the Mughan5 pathotype showed the least pathogenicity among the examined genotypes. Resistant genotypes in this research can be used as promising genotypes in wheat breeding programs.
|