Three genetics tools to improve pecan breeding at the USDA

Authors: Chatwin, Warren

Submitted to: Pecan South
Publication Type: Trade Journal
Publication Acceptance Date: 9/22/2022
Publication Date: 10/1/2022
Citation: Chatwin, W.B. 2022. Three genetics tools to improve pecan breeding at the USDA. Pecan South. 55(8):6-16.

Interpretive Summary: The biggest limiting factor in pecan breeding is the time it takes for a new seedling to mature and produce nuts. One "holy grail" of pecan breeding would be the ability to predict desirable mature traits (like nut size, shape, quality, or disease susceptibility) on juvenile seedlings and discard trees that do not have the potential to be future cultivars. The techniques to do so have existed (and have been thoroughly tested) for over a decade in other crop systems, but until recently, pecan didn't have the essential tools to begin to use this approach. This work explains the basics of three genetics tools currently being used by the USDA Pecan Breeding Program to advance pecan breeding (Family Mapping, Population Mapping, and Genomic Selection).

Technical Abstract: Traditional pecan breeding practices are based on phenotypic observations coupled with statistical evaluations and do not account for the underlying genetics. A wealth of genetic resources have been developed in recent years (genome sequences, diverse population sequencing, and multi-site bi-parental mapping populations) that enable the adoption of new genetics techniques in pecan breeding. Vetted molecular genetics techniques like Linkage Mapping, Genome-Wide Association Studies, and Genomic Selection have the potential to result in increased gains from selection, more accurate selections, and the ability to evaluate mature phenotypes of commercial importance (such as nut traits) in juvenile seedlings. In this article to Pecan South, I broadly outline the basics of each of these three genetics techniques and how our program is implementing them over the next decade.