Location: Crop Germplasm Research
2020 Annual Report
Accomplishments
1. The nuclear genome sequence of pecan. Understanding the detailed genetic make-up of pecan is critical to advancing the crop by breeding. ARS researchers at College Station, Texas, sequenced the whole genomes of the pecan cultivars, 87MX3-2.11, 'Lakota', 'Elliott', and 'Pawnee', including identification of critical genes. This accomplishment is a major advancement because the genome sequence provides the genetic blueprint of gene location and function, establishing foundational information to support pecan genetic research and breeding efforts for many years to come.
2. The chloroplast genome sequence of pecan. In addition to the nuclear genome, plants also have a chloroplast genome. It is a small, extra-nuclear genome that is critical for photosynthesis and which is generally passed from the mother to the offspring. Because of the unique inheritance pattern, chloroplast genomes can be used to trace maternal origin over many generations. ARS researchers at College Station, Texas, established the chloroplast genome sequences from two different pecan populations. This accomplishment is critical in future work to establish the origin of pecan in North America, to define evolution of the species, and to guide ongoing efforts at pecan improvement.
3. Pecan genes controlling budbreak and pecan scab. Understanding the detailed genetic control of important characteristics and traits in pecan is critical to advancing the crop and protecting it from destructive pests and diseases. ARS researchers at College Station, Texas, identified specific genes that control budbreak in pecan and also susceptibility to scab, a very destructive pecan disease. The work which focused on budbreak identified a gene that is significantly responsible for variation observed in the timing of budbreak in the spring. A gene controlling scab susceptibility was also identified. This accomplishment begins the process of definitively characterizing the genomic make-up of pecan which, as the work progresses, will greatly accelerate pecan improvement through much more tightly focused breeding efforts.
Review Publications
Cao, F., Wei, Y., Wang, X., Li, Y., Peng, F. 2019. A study of the evaluation of the pecan drought resistance of grafted 'Pawnee' trees from different seedling rootstocks. HortScience. 54(12):2139-2145. https://doi.org/10.21273/HORTSCI14341-19.
Wang, X., Rhein, H., Jenkins, J., Schmutz, J., Grimwood, J., Grauke, L.J., Randall, J. 2020. Chloroplast genome sequences of Carya illinoinensis from two distinct geographic populations. Tree Genetics and Genomes. 16:48. https://doi.org/10.1007/s11295-020-01436-0.
Cao, F., Wang, X., Liu, Z., Li, Y., Peng, F. 2019. Differential protein analysis of pecan hardwood cuttings. HortScience. 54(9):1551-1557. https://doi.org/10.21273/HORTSCI13776-18.