Sunflower breeding for resistance to the new broomrape race

Abstract

Broomrape (Orobanche cumana Wallr) is a parasitic plant that feeds on sunflower roots. In recent years, a new, aggressive race designated as race F (called biotype D in Russia) has spread drastically in Spain. The aim of our work was to find donors of resistance to this biotype, to study heredity of this trait and to develop new sunflower inbred lines combining F-race broomrape resistance with other valuable traits. Preliminary resistance tests showed that practically all VNIIMK-released and prospective inbred lines are susceptible to the new broomrape race, with only VK-623 exhibiting resistance. Consequently, we tested all breeding materials obtained from VK-623 as a parental line as well as all F1 hybrids. All F1 hybrids were susceptible to the new race, indicating that the resistance was recessive. Among the tested breeding material, resistant plants were encountered with different rates. Fifteen resistant plants were found in the progeny of two F3 morphologically different plants from a hybrid combination 14B × (VK-623 × VK-616). After testing, all of them were transplanted and self-pollinated. Their progeny proved their resistance in the next year tests. As a result two new prospective inbred sunflower lines were developed, which exhibited resistance to broomrape races C and D. However, as the recessive character of the obtained resistance creates some difficulties in commercial sunflower hybrid breeding, we shall continue to look for new dominant resistance genes donors among the sunflower samples.