QTL mapping of low temperature germination ability in cucumber

Authors: YAGCIOGLU, METIN - University Of Wisconsin; JIANG, BIAO - University Of Wisconsin; WANG, PING - University Of Wisconsin; WANG, YUHUI - University Of Wisconsin; ELLIALTIOGLU, SEBNEM - Ankara University Of Turkey; Weng, Yiqun

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/27/2019
Publication Date: 4/2/2019
Citation: Yagcioglu, M., Jiang, B., Wang, P., Wang, Y., Ellialtioglu, S.S., Weng, Y. 2019. QTL mapping of low temperature germination ability in cucumber. Euphytica. 215:84.

Interpretive Summary: Cucumber is of tropical origin and is sensitive to low temperature. Cucumber seeds with low temperature germination (LTG) ability is an ideal trait for early planting in temperate growing regions or production areas at a high altitude. However, the genetic basis for LTG ability in cucumber is poorly understood. In the present study, we conducted QTL analysis for LTG ability using a recombinant inbred line (RIL) population derived from the cross between the LTG tolerant variety Coolgreen and the sensitive inbred line 7088D. Phenotypic data on LTG ability in terms of germinate rate at 13°C were collected from 138 RILs in five environments which were used in QTL analysis. Three QTL were detected that could explain 27.3% to 52.5% observed total phenotypic variance. Two QTL had major- and minor- positive effects on increasing LTG ability, respectively, whereas one had moderate but negative effect (decreasing LTG). Additional QTL analysis was conducted using 67 recombinant F2:3 families. Work in the population further validated the presence of the major-effect QTL and narrowed this QTL down to a smaller region. Results from this study provide a basis for further fine mapping and functional study of QTL for low temperature germination in cucumber. The knowledge is also useful for marker-assisted selection in breeding for this trait.

Technical Abstract: Cucumber is of tropical origin and is sensitive to low temperature. Cucumber seeds with low temperature germination (LTG) ability is an ideal trait for early planting in temperate growing regions or production areas at a high altitude. However, the genetic basis for LTG ability in cucumber is poorly understood. In the present study, we conducted QTL analysis for LTG ability using a recombinant inbred line (RIL) population derived from the cross between the LTG tolerant variety Coolgreen and the sensitive inbred line 7088D. Phenotypic data on LTG ability in terms of germinate rate at 13°C were collected from 138 RILs in five environments which were used in QTL analysis. Three QTL, qLTG1.2, qLTG2.1 and qLTG4.1 on chromosomes 1, 2 and 4, respectively, were consistently detected across multiple environments, which could explain 27.3% to 52.5% observed total phenotypic variance. The two QTL qLTG1.2 and qLTG2.1 exhibited major- and minor- positive effects on increasing LTG ability, respectively, whereas qLTG4.1 had moderate but negative effect on decreasing LTG in this RIL population. Additional QTL analysis using 67 recombinant F2:3 families identified from 602 7088D × Coolgreen F2 plants validated the major-effect QTL qLTG1.2, which also allowed to narrow this QTL down to a region of ~352 kb in size. Results from this study provide a basis for further fine mapping and functional study of QTL for low temperature germination in cucumber. The knowledge is also useful for marker-assisted selection in breeding for this trait.