摘要 : <i>Striga</i> is a devastating parasitic weed in Africa and parts of Asia. Low <i>Striga</i> germination stimulant activity, a well-known resistance mechanism in sorghum, is controlled by a single recessive gene (<i>lgs</i>). Mole... 展开 <i>Striga</i> is a devastating parasitic weed in Africa and parts of Asia. Low <i>Striga</i> germination stimulant activity, a well-known resistance mechanism in sorghum, is controlled by a single recessive gene (<i>lgs</i>). Molecular markers linked to the <i>lgs</i> gene can accelerate development of <i>Striga</i>-resistant cultivars. Using a high density linkage map constructed with 367 markers (DArT and SSRs) and an in vitro assay for germination stimulant activity towards <i>Striga asiatica</i> in 354 recombinant inbred lines derived from SRN39 (low stimulant) x Shanqui Red (high stimulant), we precisely tagged and mapped the <i>lgs</i> gene on SBI-05 between two tightly linked microsatellite markers SB3344 and SB3352 at a distance of 0.5 and 1.5 cM, respectively. The fine-mapped <i>lgs</i> region was delimited to a 5.8 cM interval with the closest three markers SB3344, SB3346 and SB3343 positioned at 0.5, 0.7 and 0.9 cM, respectively. We validated tightly linked markers in a set of 23 diverse sorghum accessions, most of which were known to be <i>Striga</i> resistant, by genotyping and phenotyping for germination stimulant activity towards both <i>S. asiatica</i> and <i>S. hermonthica</i>. The markers co-segregated with <i>Striga</i> germination stimulant activity in 21 of the 23 tested lines. The <i>lgs</i> locus similarly affected germination stimulant activity for both <i>Striga</i> species. The identified markers would be useful in marker-assisted selection for introgressing this trait into susceptible sorghum cultivars. Examination of the sorghum genome sequence and comparative analysis with the rice genome suggests some candidate genes in the fine-mapped region (400 kb) that may affect strigolactone biosynthesis or exudation. This work should form a foundation for map-based cloning of the <i>lgs</i> gene and aid in elucidation of an exact mechanism for resistance based on low <i>Striga</i> germination stimulant activity. 收起