Molecular marker-assisted selection and resistance evaluation of rice restorer lines resistant to rice blast

【Objective】The purpose of the study was to carry out molecular marker-assisted selection and resistance evaluation of rice restorer lines resistant to rice blast, and to provide excellent genetic resources and technical reference for breeding new hybrid rice varieties with durable, broad-spectrum disease resistance and good quality. 【Method】The durable and broad-spectrum rice blast resistance genes Pi1, Pi2 and Pigm were introduced into restorer line GuiR1703 by molecular marker-assisted selection and backcross breeding techniques. Single-gene, double-gene and triple-gene introgression lines were obtained and subjected to rice blast identification and agronomic traits investigation to analyze the resistance effects among different resistance genes to rice blast and the effects of resistance gene introduction on agronomic traits of the recipient parents. 【Result】Molecular markers related to Pi1, Pi2 and Pigm genes were detected in the hybrid progenies and backcross populations. The results showed that rice blast resistance genes Pi1, Pi2 and Pigm had been successfully introduced into GuiR1703. Seven introgression lines carrying rice blast resistance genes with excellent resistance and agronomic traits were screened, showing strong resistance to rice blast. Among the single-gene introgression lines, the resistance effects of rice blast resistance genes were Pigm>Pi2>Pi1. The resistance of double-gene and three-gene introgression lines to rice blast were stronger than that of single-gene introgression lines, and the resistance of three-gene introgression lines was the strongest. The resistance effects of different gene combinations were Pi1+Pi2+Pigm>Pi2+Pigm>Pi1+Pigm>Pi1+Pi2. There was no significant difference in panicle length and 1000-grain weight between the seven rice blast resistance gene introgression lines and GuiR1703(P>0.05, the same below). The plant height of two rice blast resistance gene introgression lines was significantly higher than that of GuiR1703(P<0.05,the same below). The effective panicle per plant of one rice blast resistance gene introgression line was significantly higher than that of GuiR1703. The total grain number per panicle of three rice blast resistance gene introgression lines was significantly higher than that of GuiR1703. The seed setting rate of five rice blast resistance gene introgression lines was significantly lower than that of GuiR1703. The yield per plant of two rice blast resistance gene introgression lines was significantly lower than that of GuiR1703. The yield per plant of four rice blast resistance gene introgression lines was significantly higher than GuiR1703. 【Conclusion】Molecular marker-assisted selection can effectively aggregate multiple genes(genes Pi1, Pi2and Pigm), so that the resistance of the restorer line GuiR1703 to rice blast can be greatly improved. Moreover, A series of genetic materials that are resistant to rice blast and have similar traits to their parental traits are obtained, which can be used as a parent material for breeding hybrid rice with disease resistance and good quality.