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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Enhancement of Allium, Cucumis, and Daucus Germplasm

Location: Vegetable Crops Research Unit

2013 Annual Report


1a.Objectives (from AD-416):
Objective 1: Evaluate Allium, Cucumis, and Daucus germplasm for genetic diversity in superior horticultural and product quality traits, including: resistance to diseases and pests; growth habit that reduces weed competition; processing quality for pickling cucumbers; postharvest storage capacity for long-storing onions; flavor and nutritional qualities; and provide all relevant information to GRIN. Objective 2: Identify genetic markers and construct detailed maps of genes and quantitative trait loci associated with disease and pest resistance, abiotic stress tolerance, end product quality, and yield components in onion, cucumber, and carrot. Objective 3: Determine the genetic basis and select for pigment, phytonutrient, and flavor content in onion, cucumber, and carrot, disease and pest resistances, and field components of yield, stress tolerance and market quality. Objective 4: Develop genetic stocks and genomic resources for onion, cucumber, and carrot using recurrent inbred lines, haploids, mutant stocks, and dense maps to capture new genetic variation for desired traits, and distribute them to researchers and commercial breeders.


1b.Approach (from AD-416):
The long-term potential for improving a crop is only as great as the breadth of diversity that breeders utilize. Objective 1 targets evaluation of carrot, onion, and cucumber germplasm for traits important to growers and consumers.

Discovery Goal 1: Identify unique phenotypic variation in germplasm collections and breeding stocks to improve nutritional and processing quality, disease resistance, stress tolerance, and yield of Allium, Cucumis, and Daucus vegetables, characterize observed variation and initiate genetic incorporation of these phenotypes into elite germplasm.

Dense genetic maps are useful to improve the efficiency of crop improvement. For Objective 2 we will identify DNA polymorphisms in elite onion, cucumber, and carrot germplasm to construct genetic maps for marker-facilitated selection of major horticultural traits.

Discovery Goal 2: Identify DNA polymorphisms in elite onion, cucumber, and carrot germplasm and construct detailed genetic maps for marker-facilitated selection of major horticultural traits.

Efficient plant breeding depends on knowledge of the genetic basis of traits under selection. Objective 3 targets evaluation and genetic characterization of carrot, onion, and cucumber germplasm for traits important to growers and consumers.

Discovery Goal 3: Develop populations to determine the patterns of inheritance of unique phenotypic variation in germplasm collections and breeding stocks to improve nutritional and processing quality, disease resistance, stress tolerance, and yield of Allium, Cucumis, and Daucus vegetables, phenotype observed variation among individuals in populations, and develop genetic models to explain observed genetic patterns.

Information from germplasm evaluation and genetic analysis is useful and sets the stage for developing genetic and breeding stocks, and for establishing information resources for stakeholders. Objective 4 targets deployment of germplasm and resources.

Discovery Goal 4: Incorporate valuable traits described in Discovery Goal 3 into elite germplasm and genetic stocks using marker-assisted selection and provide stakeholders with germplasm and databases including maps.


3.Progress Report:
New carrot germplasm was collected in Morocco and field trials were initiated for carrot, onion, and cucumber. Samples were collected for carrot and onion pigments and sugars, and disease evaluation was initiated for carrot nematode and alternaria, onion pink root & Fusarium, and cucumber anthracnose and powdery mildew resistances. Deoxyribonucleic acid (DNA) samples were collected for molecular marker evaluations in carrot, onion, and cucumbers.

This research addressed Objectives 1-3 by evaluating germplasm for important traits, identifying markers and map locations, and determining the genetic basis of these traits. Objective 1: Evaluate Allium, Cucumis, and Daucus germplasm for genetic diversity in superior horticultural and product quality traits, including: resistance to diseases and pests; growth habit that reduces weed competition; processing quality for pickling cucumbers; postharvest storage capacity for long-storing onions; flavor and nutritional qualities; and provide all relevant information to the Germplasm Resources Advisory Council (GRIN). Objective 2: Identify genetic markers and construct detailed maps of genes and quantitative trait loci associated with disease and pest resistance, abiotic stress tolerance, end product quality, and yield components in onion, cucumber, and carrot. Objective 3: Determine the genetic basis and select for pigment, phytonutrient, and flavor content in onion, cucumber, and carrot, disease and pest resistances, and field components of yield, stress tolerance and market quality.


Last Modified: 10/24/2014
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