Skip to main content
ARS Home » Midwest Area » Madison, Wisconsin » Vegetable Crops Research » Research » Publications at this Location » Publication #320845
Title: Fine mapping of a dominantly inherited powdery mildew resistance major-effect QTL, Pm1.1, in cucumber identifies a 41.1 kb region containing two tandemly arrayed cysteine-rich receptor-like protein kinase genes

Author
item XU, XUEWEN - Yangzhou University
item YU, TING - Yangzhou University
item XU, RUIXUE - Yangzhou University
item SHI, YANG - Yangzhou University
item LIN, XIAOJIAN - Yangzhou University
item XU, QIANG - Yangzhou University
item QI, XIAHUA - Yangzhou University
item Weng, Yiqun
item CHEN, XUEHAO - Yangzhou University

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2015
Publication Date: 12/11/2015
Publication URL: http://handle.nal.usda.gov/10113/61931
Citation: Xu, X., Yu, T., Xu, R., Shi, Y., Lin, X., Xu, Q., Qi, X., Weng, Y., Chen, X. 2015. Fine mapping of a dominantly inherited powdery mildew resistance major-effect QTL, Pm1.1, in cucumber identifies a 41.1 kb region containing two tandemly arrayed cysteine-rich receptor-like protein kinase genes. Theoretical and Applied Genetics. 129(3):507-516. doi: 10.1007/s00122-015-2644-4.

Interpretive Summary: Powdery mildew (PM) is one of the most severe fungal diseases in cucumber (Cucumis sativus L.) and other cucurbit crops, but the molecular genetic mechanisms of powdery mildew resistance (PMR) in cucurbits are still poorly understood. In this study, through marker-assisted backcrossing with an elite cucumber inbred line D8 (PM susceptible), we developed a single segment substitution line SSSL0.7 carrying 95 kb fragment from PM resistance donor Jin5-508, which was defined by two microsatellite markers SSR16472 and SSR16881. A secondary segregating population with 3,600 F2 plants was developed from the SSSL0.7 × D8 mating; segregation analysis confirmed a dominantly inherited major-effect QTL, Pm1.1 in cucumber chromosome 1 underlying PM resistance in SSSL0.7. New molecular markers were developed though exploring the next-generation re-sequenced genomes of Jin5-508 and D8. Linkage analysis and QTL mapping in a subset of F2 plants delimited the Pm1.1 locus into a 41.1 kb region, in which eight genes were predicted. Comparative gene expression analysis revealed two concatenated genes, Csa1M064780 and Csa1M064790 encoding the same function of a cysteine-rich receptor-like protein kinase were the most possible candidate genes. GFP fusion protein-aided subcellular localization indicated that both candidate genes were located in the plasma membrane, but Csa1M064790 was also found in the nucleus. This was the first report of dominantly inherited PM resistance in cucumber. Results of this study will provide new insights into understanding the phenotypic and genetic mechanisms of PM resistance in cucumber. This work also facilitates marker-assisted selection in cucumber breeding for PM resistance.

Technical Abstract: Powdery mildew (PM) is a severe fungal disease in cucumber, but the molecular genetic mechanisms of PM resistance in cucumber are still poorly understood. In this study, through marker-assisted backcrossing with an elite susceptible inbred line D8, we developed a single segment substitution line SSSL0.7. A segregating population with 3,600 F2 plants was developed from the SSSL0.7 × D8 mating. Segregation analysis confirmed a dominantly inherited major-effect QTL, Pm1.1 in cucumber chromosome 1 was responsible for PM resistance in SSSL0.7. New molecular markers were developed by exploring the next-generation re-sequenced genomes of Jin5-508 and D8. Linkage analysis and QTL mapping delimited the Pm1.1 gene in a 41.1 kb region, in which eight genes were predicted. Comparative gene expression analysis revealed two concatenated genes encoding a cysteine-rich receptor-like protein kinase were possible candidate genes. Subcellular localization indicated that two candidate proteins were located in the plasma membrane, but Csa1M064790 was also found in the nucleus. This was the first report of dominantly inherited PM resistance in cucumber. Results of this study will provide new insights into understanding the phenotypic and genetic mechanisms of PM resistance in cucumber. This work also facilitates marker-assisted selection in cucumber breeding for PM resistance.