Peculiarities of the sunflower breeding for resistance to broomrape (orobanche cumana wallr.)

Abstract

Purpose and Objectives. Our purpose was to find available information on the sunflower breeding for resistance to the broomrape. To achieve this purpose, we solved following tasks: to review publications covering the history and current state of research into the subject; find out the specifics of such studies; and to highlight the main unresolved issues for the organization of further work.
 Materials and Methods. Publications of Ukrainian and foreign scientists became the material for the study: articles in journals and conference abstracts.
 Results and Discussion. In the article, publications covering domestic and foreign studies of the peculiarities of sunflower breeding for resistance to the parasitic plant Orobanche cumana Wallr. are collected and reviewed. The changes in the race composition of the parasite since the beginning of the 19th century, which have accelerated in recent years, are described. Experiments and breeding for resistance to the broomrape began in 1909-1913, when there was only one (the first) broomrape race A. Currently, the existence of the seventh race (G) and the broomrape biotypes affecting race G-resistant sunflower accessions has been recognized in the world. During the last 20 years, the appearance of new broomrape races was observed in the countries where sunflowers are grown with violations of crop rotation requirements.
 Marking resistance genes of domestic plants and determining the molecular polymorphism of both host and parasitic plants are important problems of genetics, solving of which is aimed at the improvement of sunflowers in terms of resistance to the broomrape. The identification of genes of resistance to the broomrape and the development of methods for their marking are discussed. Studies in the genetics of resistance to O. cumana are limited by few relevant molecular markers. Scientists announced that they had onstructed a molecular genetic map of linkage groups with the Or7 gene of resistance to race G. Genetic studies of the broomrape as a plant are mainly focused on the structure and genetic diversity of parasite populations. The broomrape aggressiveness depends on weather and climate, so an increase in temperatures and lack of precipitation can lead to the broomrape spread over large areas. Scientists adapt the phytotron test for resistance to the broomrape to modern equipment, developing certain methodological subtleties. In addition, new methods of evaluation are developed: histological and molecular genetic assessments
 Conclusions. The sunflower broomrape is one of the main biotic factors that harm the crop fields. The peculiarity of the breeding for resistance is associated with continuous formation of new races of the parasite. Studies by scientists from different countries on the formation of new physiological races of the broomrape indicate the annually growing threat from the parasite, the need for constant monitoring of broomrape populations and the continuous development of research in this direction. Several genes of resistance to the broomrape have been identified; methods of their marking have been developed; this ensures success in improving the existing and developing new progressive approaches in the sunflower breeding for resistance to the parasite. The specificity of control of resistance to the broomrape, which is determined by genetic factors, was established. Thus, genetic methods are the best ones to fight against the broomrape. However, inheritance patterns of resistance to new, virulent, widespread in Ukraine broomrape races are not described in the literature, though it is important for the creation of commercial hybrids. The relationships between resistance to new virulent broomrape races, which are common in Ukraine, and valuable economic characteristics in F1 hybrids should be also studied. Taking into account the recent climatic changes, in particular a rise in air temperatures and consequences of this global process, one can predict an increase in the intensity of damage to sunflowers by the parasite, which prompts breeders of the crop to combine resistance to adverse abiotic factors and resistance to the broomrape