Location: Nat'l Clonal Germplasm Rep - Tree Fruit & Nut Crops & Grapes
2020 Annual Report
Accomplishments
1. Crop germplasm distribution. The germplasm collections were assembled and managed to be made available to scientists, especially geneticists and breeders who develop new cultivars to address the needs of growers and consumers. Most items were shipped in March 2020 as three to five cuttings per item or accession. Leaves, pollen, and fruit are also sent if requested. ARS scientists and staff in Davis, California, shipped 6,577 items to 256 stakeholders (9 international and 247 domestic) to research and education entities when genetic diversity or genetic standards are a requirement. Not all requests can be accommodated. The majority of the shipments, more than 93 percent, were to domestic customers.
2. Evaluation of rooting ability of Prunus germplasm. Not all accessions graft well and the ability to root cuttings is an alternate propagation technique that can be utilized. Stem cuttings were collected from cultivated and wild relatives of almond, peach, and plum. These cuttings were treated with various concentrations of the rooting compound, indolebutyric acid (IBA). The almond cuttings, regardless of accession and auxin concentration basically did not root; whereas there was moderate rooting of the peaches, with best rooting of the plums. There were differences among accessions, showing that there is a genetic component to the ability of a cutting to form adventitious roots.
3. Domestication history of cultivated grape unraveled. We investigated the level and pattern of distribution of genetic diversity in a set of 1378 cultivated (Vitis vinifere) and wild (V. v. ssp. sylvestris) grapes representing a world-wide distribution. Genetic polymorphisms at 20 microsatellite loci were assayed to examine the genetic structure and differentiation within and between cultivated and wild grapes. The results indicated that there is a significant differentiation between the Western European and the Caucasus wild grapes. As might be predicted, the Caucasus wild grapes are closely allied with the Caucasus cultivated grapes and the Western European wild grapes showed close affinity to the European wine grapes. The results of this study revealed the evolutionary dynamics of domestication and contributed significantly to the understanding of domestication history of cultivated grape.
Review Publications
Chater, J.M., Merhaut, D.J., Preece, J.E. 2019. Diagnosis and management of nutrient constraints in pomegranate. In: Anoop Kumar Srivastava, Chengxiao Hu, editors. Fruit Crops, Diagnosis and Management of Nutrient Constraints. 1st edition. Elsevier. p.681-691.
Aradhya, M.K., Velasco, D., Wang, J., Ramasamy, R., You, F.M., Leslie, C., Dandekar, A., Luo, M., Dvorak, J. 2019. A fine-scale genetic linkage map reveals genomic regions associated with economic traits in walnut (Juglans regia). Plant Breeding Reviews. 138(5):635-646. https://doi.org/10.1111/pbr.12703.
Zhu, T., Wang, L., You, F.M., Rodriguez, J.C., Deal, K.R., Chen, L., Li, J., Chakraborty, S., Balan, B., Jiang, C., Brown, P.J., Leslie, C.A., Aradhya, M.K., Dandekar, A.M., Mcguire, P.E., Kluepfel, D.A., Dvorak, J., Lou, M. 2019. Sequencing a Juglans regia × J. microcarpa hybrid yields high-quality genome assemblies of parental species. Horticulture Research. 6:. https://doi.org/10.1038/s41438-019-0139-1.
Khoury, C.K., Kates, H.R., Carver Jr, D.P., Achicanoy, H.A., van Zonneweld, M., Thomas, E., Heinitz, C.C., Jarret, R.L., Labate, J.A., Reitsma, K., Nabhan, G.P., Greene, S.L. 2019. Distributions, conservation status, and abiotic stress tolerance potential of wild cucurbits (Cucurbita L.). Plants, People, Planet. 2(3):269-283. https://doi.org//10.1002/ppp3.10085.
Johnson, E.P., Preece, J.E., Aradhya, M.K., Gradziel, T. 2019. Rooting response of Prunus wild relative semi-hardwood cuttings to indole-3-butryic acid potassium salt (KIBA). Scientia Horticulturae. 263. https://doi.org/10.1016/j.scienta.2019.109144.
