Inheritance of Resistance in Sorghum to Three Pathotypes ofPeronosclerospora sorghi

Sorghum Downy Mildew of Maize – A Review

“…The first report of pathogenic variability of P. sorghi was found on sorghum crop from the USA in the late 1970s when a previously resistant and popular sorghum hybrid was infected with SDM (Craig and Frederiksen, 1980). Three distinct pathotypes were identified on sorghum in the USA from the differential reaction of the inbred lines Tx412, Tx430, CS3541 and QL-3 (Craig and Frederiksen, 1983) and their mode of inheritance of resistance was determined by Craig and Schertz (1985) and Sifuentes and Frederiksen (1988). Pawar et al, (1985) screened 75 sorghum varieties against sixteen isolates of P. sorghi from different geographic regions and found that a differential reaction identified in each isolate as a different pathotype.…”

“…Hence, SDM resistance in the crosses studied was controlled genetically by three pairs of genes with both complementary and duplicatory types of interaction involved in their genetics. Craig and Schertz (1985) used F 1 , F 2 and F 3 generations of the cross of sorghum between resistant line (QL-3) and universally susceptible line (Tx412) to determine inheritance of resistance to P. sorghi. They obtained the F 2 phenotypic ratio as 3 resistant: 1 susceptible and its genotypic ratio as one homozygous resistant: 2 heterozygous: 1 homozygous susceptible using F 3 phenotypes.…”

Sorghum

“…Genetic variation for resistance to this pathogen has also been reported [112][113][114]. Multiple races of downy mildew that infect sorghum have been identified and, consequently, resistance genes have come from multiple sources [113].…”

Peronosclerospora sorghi, o agente etiológico do míldio do sorgo

“…Embora genótipos de sorgo resistentes a P. sorghi tenham sido identificados e usados com sucesso na produção de híbridos de sorgo resistentes, poucos estudos sobre a herança da resistência têm sido relatados (Craig & Schertz, 1985). Alguns pesquisadores propuseram a hipótese de que a linhagem de sorgo QL-3, resistente às três raças identificadas no Texas, possui dois genes dominantes condicionando resistência, enquanto a linhagem SC414-12, possui um ou dois genes dominantes controlando a resistência às três raças (Craig & Schertz, 1985;Sifuentes & Frederiksen, 1988;Reddy et al, 1992).…”

“…Alguns pesquisadores propuseram a hipótese de que a linhagem de sorgo QL-3, resistente às três raças identificadas no Texas, possui dois genes dominantes condicionando resistência, enquanto a linhagem SC414-12, possui um ou dois genes dominantes controlando a resistência às três raças (Craig & Schertz, 1985;Sifuentes & Frederiksen, 1988;Reddy et al, 1992). Em trabalho realizado anteriormente na �ndia, concluiu-se que a resistência da cultivar QL3 era condicionada por 6 genes (Bhat, 1981).…”