Development Of A Series Of Introgression Lines Of The Inbred Line SiYi And Action Model Of The Two Resistance Genes To Maize Dwarf Mosaic Virus

A series of introgression lines derived from the resistant inbred Siyi and the susceptible inbred Mo17 were developed by a combination of backcross and marker assistant selection. Subsequently, action modes of the two resistant genes from Siyi were investigated using three types of near biogenic lines (NILs) with different numbers of resistant genes. Some results have been obtained as follows:1. Development of introgression lines derived from Siyi×Mo17 by backcross breeding and marker assistant selection. Individuals from BC1F1 to BC3F1 were selected by phenotyping. 96 plants from BC4F1 were singled out using 129 SSR markers distributed on the whole genome based on background of Mo17. From BC4F1 to BC6F1, the remaining markers were tested. Consequently, 26 SSSLs and 19 lines with 2-4 markers were developed, which can provide a platform for identifying elite genes from siyi.2) Investigations on action modes of two resistant genes using three types of NILs. The results showed that two resistant genes displayed dominant and complementary effects. The plants with two resistant genes showed complete resistance during whole growth stages, while other plants with single resistant gene are suspectible.The plants with the single gene on chromosome 3(RSCMV2) showed a typical diseased symptom at earlier stage about one week after inoculation, similar to the susceptible parent Mo17. These results suggest that RSCMV2 is likely an enhancer and shows increased effect of the predominant gene on chromosome 6 (RSCMV1).