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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Improvement of Cool Season Food Legumes

Location: Grain Legume Genetics Physiology Research

Project Number: 5348-21000-029-00
Project Type: Appropriated

Start Date: Apr 22, 2013
End Date: Apr 21, 2018

Objective:
In the United States, pea, lentils and chickpeas are grown primarily in the Pacific Northwest and Northern Plains. Over the past five crop seasons (2007-2012), these crops have been grown on an average of 1,260,000 acres in the US with an average harvest value of over $320 million. These crops also contribute to the success of the US wheat and barley industry by serving as useful rotation crops in small grain production systems. This research project has three objectives that focus on developing new and improved varieties of cool season food legumes (peas, lentils, and chickpeas) and effective integrated disease control strategies for these crops. 1) Develop and release new varieties and germplasm of peas, lentils, and chickpea that have higher seed mineral concentrations; improved host-plant resistance to Aphanomyces root rot, Sclerotinia wilt and Ascochyta blight; and higher yields than existing commercial varieties. 2) Identify genetic markers closely associated with superior yield, optimal plant height for harvest, seed mineral concentration, resistance to Aphanomyces root rot, and improved cold tolerance for autumn-sown peas, and validate their utility for marker-assisted plant breeding. Sub-objective 2A: Identify molecular markers in adapted pea populations that are associated with important traits including concentrations of minerals in seed, resistance to Aphanomyces root rot, and winter hardiness. Sub-objective 2B: Identify molecular markers in adapted chickpea populations that are associated with seed size and early maturity. 3) Develop efficient techniques to screen peas, lentils, and chickpeas for host-plant resistance to Ascochyta blight and Sclerotinia wilt, and characterize genetic and physiological factors responsible for the virulence of these pathogens. Sub-objective 3A: Develop efficient techniques to screen peas, lentils and chickpeas for resistance to Ascochyta blight and Sclerotinia white mold. Sub-objective 3B: Determine genetic factors responsible for pathogenicity of Sclerotinia sclerotiorum using a variety of genetic and genomic tools. Sub-objective 3C: Determine the role of solanapyrone phytotoxins produced by A. rabiei during the development of Ascochyta blight disease in chickpea. This research will result in several products, including new varieties of peas, lentils, and chickpeas along with improved methods for controlling diseases of these crops.

Approach:
New varieties and germplasm will be developed from pure lines selected from among segregating populations of peas, lentils, and chickpeas. Cyclical hybridization will be conducted to combine favorable alleles for traits of interest. Parental lines will include adapted germplasm, commercial cultivars and accessions from the various international breeding programs. Promising breeding lines will be released as either germplasm or varieties based on a rigorous comparison of their performance relative to that of commercial check varieties. Linkage analysis and the detection of associations between markers and different traits will be done using simple sequence repeats (SSRs), expressed sequence tagged- SSRs, and single nucleotide polymorphisms (SNPs). Pea recombinant inbred line (RIL) populations will be developed from a cross between Aragorn and Kiflica to identify markers associated with seed mineral concentrations. RILs from a cross between the pea cultivars Medora and Melrose will be used to identify markers associated with cold tolerance. Molecular markers associated with seed size and early maturity in chickpea will be detected using a RIL population developed from an interspecific cross between C. arientinum line Flip 90-27 and PI599072 (C. reticulatum). Associations between markers and quantitative trait loci (QTL) conditioning traits of interest will be detected by composite interval mapping. Improved methods will be developed to screen chickpea for reaction to Ascochyta blight. Toxins will be purified from liquid cultures of A. rabiei. Toxins will be adjusted to various concentrations and applied to detached chickpea leaflets. Leaflets treated with water will be used as controls. The speed of lesion development and final lesion size will be used to compare the reactions of different chickpea genotypes. The relationship between field disease scores of the chickpea genotypes and their sensitivity to the toxin will be determined. Studies to develop more efficient methods to screen peas and lentils for reaction to Sclerotinia white mold will initially examine resistant and susceptible materials reported in prior studies. Plants will be grown in the greenhouse and inoculated with agar plugs containing mycelia of S. sclerotiorum. Disease reaction will be scored by measuring the length of the lesion produced by the fungus over different time points. Two approaches will be taken to investigate the genetic factors responsible for pathogenicity and virulence of S. sclerotiorum. One approach will be to use Agrobacterium mediated transformation (AMT) to generate random mutations that will be screened to detect mutants with reduced virulence. The other approach will be to identify genes of S. sclerotiorum that are differentially expressed during the processes of infection and disease development.

Last Modified: 7/28/2014
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