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United States Department of Agriculture

Agricultural Research Service

Research Project: PHYSIOLOGICAL MECHANISMS THAT DETERMINE CROP RESPONSE TO IRRIGATION, DISEASE AND PRODUCTION PRACTICES
2011 Annual Report


1a.Objectives (from AD-416)
1. Identify physiological drought responses to quantify water-use efficiency and other physiological characteristics that influence peanut yield and quality(aflatoxin contamination, flavor, maturity) and how these traits may differ among resistant and susceptive cultivars.

2. Characterize the physiological processes and genetic expression changes that impact a level of disease tolerance to Tomato spotted wilt virus in peanuts.


1b.Approach (from AD-416)
The effectiveness of most production practices is evaluated at harvest by examining final yield. However, an understanding of the mechanisms that drive these final yield numbers is vital in determining the efficacy of production strategies and technologies. Most causal mechanisms are physiologically based; therefore, an examination of the physiological response to the production environment can help determine how production practices succeed or fail. Research will be conducted to investigate and improve the understanding of the physiological responses to environment, climate, and production practices that ultimately determine peanut yield and quality. Major emphasis will be directed towards examining the effects of irrigation type and amount on peanut physiological water use and evaluating wateruse efficiency under varying water environments. Emphasis will also be placed on plant and kernel susceptibility to aflatoxin contamination and tomato spotted wilt virus, and their effects on water use and other plant and kernel physical characteristics. A quality natural resource base is a vital factor in the viability of rural economies to sustain agricultural productivity. Available water supply is being stretched by rapidly growing demands for water by urban populations, irrigated agriculture, industry/energy sectors, and in-stream flow requirements. The dilemma for producers and local economies is finding solutions that help reduce irrigation and natural resource consumption while at the same time maintaining and or enhancing producer net returns.


3.Progress Report
Research plots were established on controlled rainout shelter to determine the level of drought resistance in different peanut germplasms. Plants were subjected to water deficit at various times during peanut development to determine critical stages of peanut growth that will affect peanut yield and quality. Ongoing evaluations of peanut breeding lines are being conducted. For the current crop year: 560 breeding progeny lines arranging from F2 to F7 are being grown in Headland, AL. Advanced line tests have been conducted at two locations in AL and GA in southeastern region. The cross between ‘C76-16’ and ‘Georgia Green’, two lines indentified as drought tolerant germplasm and supposed to have different alleles with different drought tolerant mechanisms, has been made in the greenhouse in 2011. The cross will provide a F2 progeny to proof our hypotheses and eventually to breed a new line with genes stacked. A mapping population is also grown in Headland, AL in 2011 for genotyping tomato spotted wilt virus, leaf spot, and other important agronomic traits. The data will be used to identify molecular markers associated with desirable traits that can be applied in peanut breeding program and to isolate the genes that can be used in peanut genetically-modified project.


4.Accomplishments
1. In March 2011, ‘AU-1101’ (Reg. No. CV-xxx, PI 661498), a large-seeded Virginia-type peanut, was released. Besides high yield, uniform pod size and shape, high grade, superior shelling characters, low oil content, and good flavor, AU-1101 is an early-medium maturity peanut cultivar. Early maturity and drought tolerance are the ways of reducing the amount of irrigation required.

2. Antibody testing is available for Tomato spotted wilt virus that attacks peanuts; however, its accuracy compared to a more sensitive method (polymerase chain reaction) was in question. Utilizing field collected samples, two methods were compared which showed no statistical difference between the two methods to detect the virus. This result translates to time saving and reduces cost since antibody testing can confidently be utilized for the testing of the virus in peanut.

3. Molecular markers are important in breeding programs and there is a need to identify and validate more markers in peanuts. A total of 138 novel molecular markers were discovered and tested to be functional. This new resource will help to map important traits in peanuts.

4. Aphid is a pest in many crops and carries diseases. As an international collaborative effort to understand the genome of the pea aphid, the genome was sequenced and annotated and will be utilized by the international research community. This resource will benefit many levels from farmers to researchers and industries.


Review Publications
Li, Y., Chen, C.Y., Knapp, S.J., Culbreath, A.K., Holbrook Jr, C.C., Guo, B. 2011. Characterization of simple sequence repeat (SSR) markers and genetic relationships within cultivated peanut (Arachis hypogaea L.). Peanut Science. 38:1-10.

Grey, T.L., Beasley, J.P., Webster, T.M., Chen, C.Y., Bridges, D.C. 2011. Peanut seed vigor elavuation using a thermal gradient. International Journal of Agronomy. DOI: 10/1155/2011/202341.

Hunter, W.B., Shelby, K., Boykin, L.M., Dang, P.M., Weathersbee III, A.A. 2009. Ribosomal proteins and expressed sequence tags from Lysiphlebus testaceipes (Hymenoptera: Aphidiidae). Florida Scientist. 72(3):196-207.

Richards, S., Gibbs, R., Stern, D., Tagu, D., Hunter, W.B., Dang, P.M., Evans, J.D. 2010. Genome sequence of the Pea Aphid Acyrthosiphon pisum. International Aphid Genomics Consortium: Pea Aphid Genome Annotation Workshop. DOI: 10.1037?journal.pbio.1000313.

Yuan, M., Gong, L., Meng, R., Li, S., Dang, P.M., Guo, B., He, G. 2010. Development of trinucleotide (GGC)n SSR markers in peanut (Arachis hypogaea L.). Electronic Journal of Biotechnology. 13:6. DOI: 10.2225/vol13-issue6-fulltext-6.

Dang, P.M., Rowland, D., Faircloth, W.H. 2009. Comparison of ELISA and RT-PCR assays for the detection of Tomato spotted wilt virus in peanut. Peanut Sci. 36:133-137.

Wang, M.L., Sukumaran, S., Barkley, N.L., Chen, Z., Chen, C.Y., Guo, B., Pittman, R.N., Stalker, H., Holbrook Jr, C.C., Pederson, G.A., Yu, J. 2011. Population structure and marker-trait association analysis of the U.S. Peanut (Arachis hypogaea L.) mini-core collection. Journal of Theoretical and Applied Genetics. 123:1307-1317.

Zhang, L., Kyei-Boahen, S. 2011. Effects of spring post-planting flooding on early soybean production systems in Mississippi. Crop Management. DOI: 10.1094/CM-2011-0722-01RS.

Last Modified: 12/22/2014
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