Identification of the genes resistant to brown rust in winter soft wheat varieties with the use of conventional and modern research methods

Brown rust is the main disease of wheat soft varieties in the Rostov region. The majority of wheat varieties (more than 87%) developed in the FSBSI “Agricultural Research Center “Donskoy” show resistance to this causative agent. In order to obtain a complete immunological characteristics of the developed varieties, there were carried out the researches to identify the resis­tance genes (Lr) in the early and adult stages of plant growing in cooperation with the Mycology and Phytopathology Laboratory of the FSBSI ARIZR. There were studied 37 varieties of winter soft wheat on the infectious fields of the south and northwest of Russia, as well as by the methods of a phytopathological test (to three isolates of the fungus with virulence to TcLr9, TcLr19, TcLr26 and the Zernograd pathogen population) and by the PCR analysis using 10 molecular markers Lr1, Lr3, Lr9, Lr10, Lr19, Lr20, Lr24, Lr26, Lr34 and Lr37. DNA was isolated by a micro-method according to K. Edwards, the PCR was carried out in a C-1000 amplifier (Bio Rad, US). The study established that there were no universal varieties among the studied ones which were resistant to all three clones and the Zergograd population. The varieties “Polina”, “Volnitsa” and “Zernogradka 11” showed resistance to the three clones, but in the phase of sprouting they show susceptibility to the pathogen population. According to the results of PCR analysis, the resistance genes Lr9, Lr19, Lr24, Lr26 were also not found in the varieties. 29 out of 37 studied varieties contained the adult resistance gene Lr34, and 20 varieties had the inefficient gene Lr3, which neither apart nor together could protect the plants from brown rust in the field. This indicates that the tolerant varieties carry additional non-identified Lr-genes. In a number of varieties there have been established 2 resistance genes. The variety “Kipchak” susceptible in the field contained the Lr1 gene, which lost its effectiveness. The differences in the damage degree of some varieties in the conditions of the Rostov region and St. Peters­burg indicate a difference in the North Caucasian and northwestern populations by virulence to the causative agent of brown rust