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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCING DISEASE RESISTANCE AND OIL QUALITY ATTRIBUTES OF PEANUT
2013 Annual Report


1a.Objectives (from AD-416):
The long-term objective of this project is to improve the genetics of peanut for disease resistance and the oleic acid content of oil. Objective 1. Develop peanut germplasm that is high-oleic in nature with improved resistance to Sclerotinia blight and southern blight. Objective 2. Develop molecular markers for peanut associated with resistance to Sclerotinia blight and southern blight. Objective 3. Develop improved methodology to characterize the reaction of Sclerotinia minor and Sclerotium rolfsii on inoculated peanut germplasm and breeding lines under greenhouse conditions.


1b.Approach (from AD-416):
Parental lines being used in such crosses include Arachis hypogaea L. cultivars, advanced breeding lines, and plant introductions (PIs) with demonstrated Sclerotinia disease resistance and high oleic acid content. New and existing potential parent lines with high oleic acid content are continually tested in the greenhouse and field plots for resistance to Sclerotinia blight and southern blight and are readily available for use in the peanut breeding program. Included in our annual screening of germplasm for disease resistance are cultivars, breeding lines, and germplasm accessions. Also, collaborators include the curator of the U.S. peanut germplasm collection as well as other breeders who are continually evaluating accessions for value added traits. Molecular markers for Sclerotinia resistance will be identified and verified by phonotypic reaction.


3.Progress Report:
The long-term objective of this project is to improve the genetics of peanut for disease resistance and the oleic acid content of oil. This project expired on 2/4/13 and was replaced by 6217-21220-007-00D (2/5/13 – 2/4/18). Over the life of this project we have made significant progress toward that end. Regarding Objectives 1 and 2, we have identified a molecular marker that is linked to Sclerotinia blight in peanut, which has resulted in a reduction in the amount of time spent screening breeding lines and germplasm collections for disease resistance. This marker was used to screen the US Peanut Mini-Core and ICRISAT germplasm collections, and identified a total of 106 new possible sources of Sclerotinia blight resistance. We developed a new technique to determine the concentration of oleic and linoleic acid in a single peanut seed. This accomplishment is important because the method will allow scientists to screen for value-added genetic traits without spending the time and resources to grow the plants in the greenhouse or field first and will avoid the extreme costs of sending numerous samples to quality labs for testing. Progress towards attaining Objective 1 was substantially made when this program officially released a new high oleic runner type cultivar "Red River Runner". This new variety has acceptable resistance to Sclerotinia blight, excellent oil chemistry and sensory attributes, acceptable yield, and superior grade which will increase the peanut producer's profit margin by $50-$100 per acre. A high oleic Spanish germplasm line, ARSOK-S1, was released in 2013 for use in peanut breeding programs. This germplasm exhibits enhanced resistance to pod rot, Sclerotinia blight, and southern blight, and will be an excellent line to incorporate into breeding programs focused on multiple disease resistance. Additionally, breeding lines with improved genetics for the high oleic trait as well as resistance to Sclerotinia blight are now in their 5th year of performance trials. These advanced lines include a high oleic runner type peanut with the highest resistance to Sclerotinia blight reported to date, along with yield, grade, flavor, and shelling characteristics comparable to Red River Runner,and is expected to be released in 2015. We have developed the first high oleic Virginia peanut line with Sclerotinia blight and pod rot resistance adapted for growth in the US Southern Plains. This line is also in its second year as a national Uniform Peanut Performance Test entry. With regard to Objective 3, we defined the post inoculation relative humidity on the infection of peanut with Sclerotinia minor. We determined that under relative humidity of 100% it takes 24 hours to initiate successful infection and normal expansion of lesions caused by S. minor. We also compared inoculation of peanut leaflets with that of stem inoculation to quantify disease reaction of S. minor on Sclerotinia-resistant and s-usceptible peanut entries. Stem inoculation was superior to leaflet inoculation in identifying physiologic resistance in peanut to S. minor based on rate of lesion expansion.


4.Accomplishments
1. Release of "Red River Runner" peanut. Investigators at Stillwater, Oklahoma, developed and released a superior new peanut variety "Red River Runner". This new variety has resistance to Sclerotinia blight, excellent oil chemistry and sensory attributes, good yield, and superior grade. This cultivar is fast becoming the most widely sought runner variety for commercial production, primarily in the Southwestern US production region, but requests for seed have also come from Arkansas and Mississippi. Red River Runner was grown on approximately 20% of runner peanut acreage in 2012 (increasing peanut producer's profits approximately $2M), and its production is limited only by seed availability. This accomplishment is significant because the production of this new peanut variety will increase the peanut producer's profit by $50-$100 per acre, and potentially increase the peanut industry by $5M annually.

2. Release of high oleic Spanish germplasm ARSOK-S1. Investigators at Stillwater, Oklahoma, developed and released a high oleic Spanish germplasm line, ARSOK-S1. This germplasm line exhibits enhanced resistance to pod rot, Sclerotinia blight, and southern blight, and will be an excellent line to incorporate into breeding programs focused on multiple disease resistance. This accomplishment is significant because peanut breeders and researchers can include this disease-resistant germplasm in their breeding programs and easily pyramid these traits with those of superior agronomic performance, reducing the time and effort needed to develop new peanut varieties.


Review Publications
Melouk, H.A., Chamberlin, K.D., Godsey, C., Damicone, J.P., Burow, M.D., Baring, M.R., Simpson, C.E., Dashiell, K.E., Payton, M. 2013. Registration of 'Red River Runner' peanut. Journal of Plant Registrations. 7(1):22-25.

Last Modified: 12/18/2014
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