Developing genetically segregating populations for localization of novel sugarcane brown rust resistance genes

Brown rust caused by Puccinia melanocephala H. Sydow & P. Sydo is an important sugarcane disease that severely threatens sugarcane production in China. Breeding and planting resistant cultivars is the most cost-effective and efficient strategy for the control the disease. In addition, exploration, research, and utilization of resistant genes are the basis for resistance breeding. In the present study, four sugarcane varieties without the Bru1 gene and highly resistant to brown rust were used as male parents, and four varieties highly susceptible to brown rust were used as the female parents to configure hybrids. Six F1 hybrid populations were subjected to authenticity determination using SSR markers, brown rust resistance phenotype identification using artificial inoculation, and molecular detection of Bru1 gene. The results showed that the genetic segregation ratios in F1 hybrid populations of Yuetang 03-393 (HS) × ROC24 (HR) and Liucheng 03-1137 (HS) × Dezhe 93-88 (HR) were 3R:1S and 1R:3S, respectively, and Bru1 gene was not detected in their F1 hybrids. The results indicated that two dominant novel genes controlled brown rust resistance in Yuetang 03-393 (HS) × ROC24 (HR) and two recessive novel genes controlled brown rust resistance in Liucheng 03-1137 (HS) × Dezhe 93-88 (HR). Two genetically segregating populations that could be used for the localization of novel brown rust resistance genes were developed in the present study, and could lay a suitable foundation and provide theoretical reference for the analysis of the genetic mechanism of brown rust resistance, genetic map construction, mapping of novel resistance genes and the development of closely associated molecular markers in the future.