Coordinated Development of Genetic Tools for Pecan
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Pecan (Carya illinoinensis) is a large deciduous native North American tree grown in 27 US states by about 25,000 pecan farmers for its delicious and highly nutritious nutmeats; thus, it has great economic impact in rural communities across much of the U.S. It is considered a permanent crop, as trees bear for 300+ years. Pecan is recently domesticated, as commercial orchards were first planted in the late 1800s. It is successfully farmed in areas as diverse as the deserts of the southwestern US, the humid southeastern US, California's Central Valleys, the Southern Plains, and is substantially planted worldwide (Grauke et al., 2011). Growing regions within the U.S. are diverse, with farmers in each region facing major and unique horticultural issues. The horticultural issues to be addressed by genetic tool development include flowering, severe alternate bearing, disease susceptibility, salinity stress, drought stress tolerance, and micronutrient uptake insufficiencies. Project long-term goals are to increase pecan nutmeat yield and quality, optimize nutritional value, and subsequent stabilization of pecan markets by improving crop major limiting characteristics for all U.S. pecan farming regions. The objectives are focused to elucidate the genetics of these crop characteristics. Genetic variation within the species allows for differential adaptation in wide ranges of environments; thus, unraveling the genetics of several genotypes will allow for identification of genes controlling specific traits. Obtained data will allow development of vital genetic tools necessary for increasing understanding of regional adaptation, promoting conservation, and selecting improved cultivars/rootstocks for all major farming regions. All sectors of the industry will benefit--i.e., nurseries, producers, nutmeat marketers, consumers, and the interdisciplinary research community. The knowledge and tools generated will be available on public websites and disseminated to growers, nurseries, commercial marketers, consumers, and researchers.Pecan, a Native American Algonquin word describing a ''nut requiring a stone to crack'' (Trumball, 1872), is North America's most economically valuable native tree nut. Its cultivation impacts farmers and farm communities across the southern U.S. As an only-recently domesticated crop species, the development of genetic tools is essential for effectively addressing key constraints to stable and high quality nutmeat production. As the pecan industry has evolved since its inception in the late 1800s, trees have been introduced as an exotic crop to be farmed in relatively alien environments, and this has led to major stress-associated horticultural problems either directly or indirectly altering flowering and alternate bearing. The identification of genetic elements controlling key traits, such as efficient nutrient uptake/transport, scab disease resistance, salinity tolerance, drought tolerance, and nut quality need identification and integration to produce better adapted cultivars for cultivation. Identification of these underlying genetic elements and subsequent development of genetic markers associated with specific traits potentially influences the economics of pecan farming and marketing. Development of trees better suited for specific environments will yield quantitatively and qualitatively superior nutmeats and require less input by growers. This would increase the economic fitness of pecan growers while also enabling more environmentally friendly/sustainable pecan horticulture. Through our research and outreach efforts, the goal of this project is to discover and implement science-based solutions resulting in a stable supply of high-quality pecans over time. This will be of enormous benefit to all sectors of the U.S. pecan industry, from producers to processors and ultimately to consumers and rural communities throughout much of the US.We will use trans-disciplinary approaches to build genetic tools that the pecan industry recognizes as essential for their success. Research institutions include New Mexico State University (1862 land grant/Hispanic serving), University of Arizona, University of Georgia, The Samuel Roberts Noble Foundation, HudsonAlpha, USDA-ARS Southern Regional Research Center (New Orleans, LA), USDA-ARS Pecan Breeding and Genetics/National Collection of Genetic Resources for Pecans and Hickories (College Station, TX), and USDA-ARS Southeastern Fruit and Tree Nut Research Laboratory (Byron, GA). This trans-disciplinary research group contains the following expertise: plant genetics, plant molecular biology, pecan tissue culture, plant pathology, pecan breeding, pecan horticulture, soil science, agricultural economics, computer science, and outreach/extension. A panel advisory group has also been created that will include agricultural consultants, producers with large- and small-scale pecan orchards, pecan shellers, and nurserymen. The simplified goals of this proposal are 1. To evaluate the genetics that controls the diversity of native pecan. This will be done by obtaining genomic sequences, annotation of the genes, developing linkage maps and SNP markers; 2. Evaluate the molecular mechanisms of flowering, disease resistance, and tolerance to stresses; and 3. Build a designated database/website that will be available to share data and impact of the research with all sectors of the pecan industry.