Race-specific leaf and root resistance of winter oilseed rape (Brassica napus L.) to Xanthomonas campestris pv. campestris

Background. Researchers from France, Serbia, and Russia have reported the spread of Black Rot in winter rape crop. The cultivation of resistant varieties and hybrids is considered to be the most effective method of reducing the economic damage caused by the disease. The complexity of breeding for resistance to Black Rot lies in the presence of at least 11 races of the pathogen Xanthomonas campestrispv. campestris, each of which requires its own resistance gene. Studies of race-specific resistance of winter rapeseed are limited to the study of resistance to 1 and 4 races of Xanthomonas campestrispv. campestrisusing leaf-piercing technique. Purpose. The objective of this research is to study the manifestation of leaf and root resistance of rapeseed to Black Rot and to identify sources of high race-specific resistance to 1, 3, 4, and 6 races of Xanthomonas campestrispv. campestris. Materials and methods. Artificial screening of resistance to black rot was carried out using a genetic collection of winter rapeseed, represented by 30 accessions. Inoculation using bacterial suspensions of Xanthomonas campestrispv. сampestriswas conducted under controlled conditions of a climate chamber. The inoculation process involved leaf-piercing technique by clipping the leaf edges near the veins using forceps or root traumatization. Black rot resistance or susceptibility were estimated on a two-point scale. Results. One source of leaf resistance to race 4 of Xanthomonas campestrispv. campestris“Tegg” was identified in the genetic collection of winter rapseed. When plants were inoculated using the root traumatization system, the samples Dagg with root resistance to Xanthomonas campestrispv. campestrisrace 4 and Fagg with root resistance to race 3 were identified. Conclusion. Two independent race-specific systems of resistance to black rot have been identified in winter rapeseed, which are manifested using different methods of inoculation with Xanthomonas campestrispv. campestrispathogen. The identified sources of resistance can be used in rapeseed breeding programs for resistance. Hybridologic and molecular genetic analysis of each of the identified resistance systems is required.