2017 Texas A&M Plant Breeding Symposium: Dr. LJ Grauke

The Texas A&M Plant Breeding Symposium is part of the DuPont Plant Science Symposia Series. The 2017 symposium themed "The Vavilov Method: Utilizing Genetic Diversity" celebrated the life and career of Nikolai Vavilov. He is one of the most influential scientist of the 20th century and a pioneer in genetic resource preservation. The main goal of the symposium today is to hear from plant scientist and breeders who are applying Vavilov’s ideas through conservation, collecting, and effectively utilizing genetic diversity in modern crop breeding programs.

L.J. Grauke is Curator of the National Collection of Genetic Resources for Pecans and Hickories (NCGR-Carya). He is also the Research Horticulturist for the USDA-ARS Pecan Breeding & Genetics program.

Title: Carya: The Next Generation

Abstract: The USDA ARS National Collection of Genetic Resources for Carya (NCGR-Carya) has been dramatically impacted by Vavilov’s contributions. However, the constraints of our genus create unique challenges. Pecan [Carya illinoinensis] is a large, slow to bear, long-lived, wind-pollinated, out-breeding, deciduous tree species native to North America and Mexico. The archaeological record of Carya nut use by humans spans over 10,000 years, while pecan cultural development in grafted orchards began in the mid 1800’s. Diverse stands of largely unmanaged native trees compete in the market with nuts from intensively managed orchard systems. Co-evolved insects and diseases exert selection and management pressure and provide targets for improvement through breeding. The USDA Pecan Breeding Program began in 1930, with the goal of producing large crops of high quality nuts for use in regionally diverse, grafted pecan orchards. Until 1998, the USDA effort was the only pecan breeding program. The cultivars used as parents by the first breeder became the core of the National Clonal Germplasm Repository for Pecans and Hickories when it was designated in 1984. At the first meeting of the ad hoc Crop Germplasm Committee in 1984, a Vavilovian strategy was adopted to collect range wide native populations of pecans to represent variation related to distribution. Since seed does not maintain viability in storage it is necessary to maintain collections as living trees. This provides the opportunity to observe patterns of variation in tree performance related to geographic origin. Repository collections have been the foundation for the development of molecular genetic methods of characterization in Carya, and have been pursued in conjunction with refinement of phenotypic descriptors necessary for selection in the breeding program. The first few microsatellite markers (SSRs) were used for cultivar verification and analysis of the geographic distribution of genetic diversity. Appropriate targets for use as reference genomes were identified and sequencing initiated. Utility of the draft template sequence has engaged a broader team of scientists in the characterization of diversity. How that diversity can be productively and cooperatively integrated into development of multiple national and international breeding programs, while protecting the diversity and resilience of native populations and producers, is a challenge for the next generation to which Vavilov’s concepts continue to contribute.