The goal of my research program is to discover and characterize apple genes or gene networks controlling traits of horticultural and/or economic importance using tools of plant genomics. The research findings of the program will (1) advance our knowledge in understanding the underlying mechanisms of these traits, and (2) enable us to develop and integrate efficient approaches and tools for the improvement of apple scion varieties and rootstocks.
The goal of my research program is to discover and characterize apple genes or gene networks controlling traits of horticultural and/or economic importance using tools of plant genomics. A few traits unique to or essential in plant growth and development, plant reaction to biotic/abiotic stresses, and fruit shelf life and quality have been targeted. Several research projects are currently ongoing, including development of EST based SSR markers and construction of genetic maps for Malus × domestica cv ‘Royal Gala’ and an apple scab resistant accession of M. sieversii (a primary wild progenitor species for the domesticated apple); identification and characterization of Malus ERF genes involved in waterlogging tolerance in apple rootstocks; fine-scale genetic/physical mapping of the Co locus responsible for the columnar tree type; and an investigation into the interactions of genes related to ethylene production and fruit ripening.
Outreach and Extension Focus
My extension activities are tailored to regularly alert industry stake holders of the capabilities and benefits of plant genome research for fruit production and management through findings in my research program.
Awards and Honors
- Presidential Early Career Awards for the accomplishment in apple genomics studies (2016) The Whitehouse
- The Tech Awards-Economic Development (2012) The Tech Museum of Innovation
- The CGIAR Science Award (2007) The Consultative Group on International Agricultural Research
- Dougherty, L., Zhu, Y., & Xu, K. (2016). Assessing the allelotypic effect of two aminocyclopropane carboxylic acid synthase-encoding genes MdACS1 and MdACS3a on fruit ethylene production and softening in Malus. Horticulture Research. 3:16024:10.
- El-Sharkawy, I., Dong, L., & Xu, K. (2015). Transcriptome analysis of an apple (Malus ×domestica) yellow fruit somatic mutation identifies a gene network module highly associated with anthocyanin and epigenetic regulation. Journal of Experimental Biology. 66:7359-7376.
- Bai, Y., Dougherty, L., Cheng, L., & Xu, K. (2015). A co-expression gene network associated with developmental regulation of apple fruit acidity. Molecular Genetics and Genomics. 290:1247-1263.
- Bai, Y., Dougherty, L., Cheng, L., Zhong, G., & Xu, K. (2015). Uncovering co-expression gene network modules regulating fruit acidity in diverse apples. BMC Genomics. 16:16 pp..
- Bai, Y., Dougherty, L. E., & Xu, K. (2014). Towards an improved apple reference transcriptome using RNA-seq. Molecular Genetics and Genomics.
- Xu, K., Wang, A., & Brown, S. K. (2012). Genetic characterization of the Ma locus with pH and titratable acidity in apple. Molecular Breeding. 30:899Ð912.
- Wang, A., & Xu, K. (2012). Characterization of Two Orthologs of REVERSION-TO-ETHYLENE SENSITIVITY1 in Apple. Journal of Molecular Biology Research. 2:24-41.
- Bai, Y., Dougherty , L., Li, M., Fazio, G., Cheng, L., & Xu, K. (2012). A natural mutation-led truncation in one of the two aluminum-activated malate transporter-like genes at the Ma locus is associated with low fruit acidity in apple. Molecular Genetics and Genomics. 287:663-678.
- Bai, T., Zhu, Y., Fernández-Fernández , F., Keulemans, J., Brown, S. K., & Xu, K. (2012). Fine genetic mapping of the Co locus controlling columnar growth habit in apple. Molecular Genetics and Genomics. 287:437-450.
- Wang, A., Aldwinckle, H. S., Forsline, P. L., Main, D., Fazio, G., Brown, S. K., & Xu, K. (2012). EST contig-based SSR linkage maps for Malus x domestica Royal Gala and an apple scab resistant accession of M. sieversii, the progenitor species of domestic apple. Molecular Breeding. 29:379-397.