Spines or trichomes on the fruit of cucumbers enhance their commercial value in China. In addition, glabrous mutants exhibit resistance to aphids and therefore their use by growers can reduce pesticide residues. Previous studies have reported two glabrous mutant plants containing the genes,
csgl1 and
csgl2. In the present study, a new glabrous mutant, NCG157, was identified showing a gene interaction effect with
csgl1 and
csgl2. This mutant showed the glabrous character on stems, leaves, tendrils, receptacles and ovaries, and there were no spines or tumors on the fruit surface. Inheritance analysis showed that a single recessive gene, named
csgl3, determined the glabrous trait. An F
2 population derived from the cross of two inbred lines 9930 (a fresh market type from Northern China that exhibits trichomes) and NCG157 (an American processing type with glabrous surfaces) was used for genetic mapping of the
csgl3 gene. By combining bulked segregant analysis (BAS) with molecular markers, 18 markers, including two simple sequence repeats (SSR), nine insertion deletions (InDel) and seven derived cleaved amplified polymorphism sequences (dCAPs), were identified to link to the
csgl3 gene. All of the linked markers were used as anchor loci to locate the
csgl3 gene on cucumber chromosome 6. The
csgl3 gene was mapped between the dCAPs markers dCAPs-21 and dCAPs-19, at genetic distances of 0.05 cM and 0.15 cM, respectively. The physical distance of this region was 19.6 kb. Three markers, InDel-19, dCAPs-2 and dCAPs-11, co-segregated with
csgl3. There were two candidate genes in the region,
Csa6M514860 and
Csa6M514870. Quantitative real-time PCR showed that the expression of
Csa6M514870 was higher in the tissues of 9930 than that of NCG157, and this was consistent with their phenotypic characters.
Csa6M514870 is therefore postulated to be the candidate gene for the development of trichomes in cucumber. This study will facilitate marker-assisted selection (MAS) of the smooth plant trait in cucumber breeding and provide for future cloning of
csgl3.
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