DONORS OF GREENBUG RESISTANCE IN SORGHUM
Background. Greenbug (<i>Sсhizaphis graminum</i> Rondani) is a key pest of sorghum. By now, 15 resistance genes have been identified in this crop. The <i>Sgr5</i> - <i>Sgr15</i> resistance genes have not being used in breeding; however, differential interaction with the herbivore was revealed only for the accessions protected by the <i>Sgr7</i> - <i>Sgr11</i> genes. The necessity to continue searching for sorghum accessions with new resistance genes is quite obvious. Materials and methods. Under laboratory conditions, resistance to a Krasnodar population of <i>S. graminum</i> was analyzed in 13 accessions weakly damaged by this herbivore. Besides, the resistance of the earlier selected grain sorghum accessions from China and of F<sub>1</sub> hybrids from crosses of these forms with susceptible sterile lines was studied. Segregation for resistance to the aphid population in the F<sub>2</sub> hybrids from crossing the accessions k-1239 and k-1251 with susceptible testers was also analyzed. Segregation for resistance to a clone weakly damaging the cultivar ‘Sarvashi' was studied in the F<sub>2</sub> ‘Sarvashi s' × k-1251. When studying genetic control of sorghum resistance to the aphid, two experimental approaches were applied: examination of the differential insect-host interaction, and hybridological analysis. Results and conclusions. Nine accessions of grain, sweet and wild sorghum, protected by alleles of greenbug resistance genes differing from earlier identified alleles of the <i>Sgr1</i> - <i>Sgr6</i> and <i>Sgr12</i> genes, have been selected. Pure lines k-105, k-533, k-1239, k-3650, k-6339 and k-10524 selected from grain and sweet sorghum samples are most promising for use in breeding for resistance. A dominant inheritance pattern of greenbug resistance was demonstrated by ten grain sorghum accessions from China: k-830, k-831, k-931, k-932, k-933, k-1238, k-1239, k-1241, k-1251 and k-2588. Each of the accessions k-1239 and k-1251 has two highly effective resistance genes (dominant and recessive), which are not identical to alleles of the effective <i>Sgr5</i> and <i>Sgr6</i> genes.