Abstract:

【Objective】 The objectives of the research are screening molecular markers of sorghum resistance gene to head smut physiological race 3 by using SSR. Once the molecular markers are found, it would become true to select resistant lines in the indoor laboratory, and the evaluation in the field may be neglected. 【Method】 Bulked segregation analysis (BSA) was applied in the study. Two segregation population, restorer line population (R population) 2381R/Aisi and maintainer line population (B population) Tx622B/7050B, were used in the research. 【Result】 The resistance to sorghum head smut physiological race 3 is a qualitative trait inheritance. It has a dominant genetic effect. F1 would be resistant, too, provided one of the parents is resistant, It is the first time getting two stable SSR markers which can be used as molecular markers of sorghum resistance genes to head smut physiological race 3, they are Xtxp13 and Xtxp145. Xtxp13 located in linkage group B, and Xtxp145 located in linkage group I. The recombination percentage between marker and resistant gene are 9.6% and 10.4%, respectively. The genetic distances to resistant gene are 9.6 cM and 10.4 cM, respectively. 【Conclusion】 The resistance to sorghum head smut physiological race 3 may be controlled by two mutual independent nonallelic genes, and there is interaction between them. It is found that molecular markers are easier to find in B population than R population during the screening of SSR markers. It may show the different resistance mechanism between restorer line and maintainer line.

Key words: sorghum, head smut, inheritance mechanism, resistant gene, marker