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. Progress towards attaining that objective 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 that will increase the peanut producer's profit margin by $50-$100 per acre. 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. Over 1 million pounds of seed were produced in the 2011 growing season for either seed production or commercial sale. Further progress will be made by the development of a superior high oleic Spanish peanut breeding line that has been identified and targeted for release in 2013. Additionally, advanced breeding lines with improved genetics for the high oleic trait as well as resistance to Sclerotinia blight are now in their fourth year of performance trials, and these trials have been expanded to include 4 locations in Oklahoma and the national Uniform Peanut Performance Tests (UPPT). These advanced lines include a high oleic runner type peanut with the highest resistance to Sclerotinia blight reported to date. This breeding line (ARSOK-R35) also has excellent yield and grade potential, along with superior oil and sensory analysis. Also included in this group of advanced breeding lines are two high oleic Virginia type peanuts (ARSOK-V30A and ARSOK-V30B) with enhanced resistance to Sclerotinia blight and pod rot, along with excellent yield and grade potential. When released, one of these lines will be the first high oleic Virginia cultivar adapted for and released for production in the Southwestern US. Further progress was also made toward placing the molecular marker for Sclerotinia blight resistance on the tetraploid peanut map. Genotypic and phenotypic data from one mapping population was gathered and six other populations are currently being generated (now in the F2:F5 stage of development) since the original populations were lost due to natural disaster in the field. Mapping will begin in another year. Placing this molecular marker on the tetraploid peanut map will aid in the identification of a QTL for Sclerotinia blight resistance and in marker-assisted selection in breeding programs.
1. Development of improved advanced breeding lines for variety release. Profitable peanut production relies heavily on the consistent release of improved varieties. Through years of advanced testing, we have identified new lines for release as cultivars. ARSOK-R35 is an advanced runner type breeding line with greatly enhanced resistance to Sclerotinia blight, high oleic acid oil chemistry, superior yield, and excellent grade potential. ARSOK-30A and ARSOK-30B are advanced Virginia type breeding lines with enhanced resistance to Sclerotinia blight and pod rot, high oleic acid oil chemistry, and excellent yield and grade potential. ARSOK-S140-1OL is an advanced Spanish breeding line with enhanced resistance to Sclerotinia blight and Southern blight, high oleic acid oil chemistry, excellent yield and grade, and a seed size preferred for Spanish peanuts by the shelling industry. The release of these breeding lines as varieties available for production will decrease producer inputs per acre and increase their overall profit margin. ARS researchers in Stillwater, Oklahoma, expect all lines to be released within 3 years.
Chamberlin, K.D., Melouk, H.A., Madden, R.D., Dillwith, J.W., Bannore, Y.C., El Rassi, Z., Payton, M.E. 2011. Determining the oleic/linoleic acid ratio in a single peanut seed: A comparison of two methods. Peanut Science. 38(2):78-84.