|El Rassi, Ziad|
Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/9/2011
Publication Date: 7/15/2011
Citation: 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. Interpretive Summary: Tomato Spotted Wilt Virus (TSWV) is a virus that infects peanuts, primarily in the southeastern United States, and is spread by the insect thrips. The virus causes millions of dollars in profit loss to peanut producers each year. In the last decade, the virus has spread to the southern region of Texas, causing loss in profit there as well, and has recently been consistently reported in peanut production regions of Oklahoma. At present time, the only tool that is available to manage TSWV in the peanut field is that of resistant cultivars. Insecticide application is not effective in preventing the spread of thrips due to the fact that they are primarily dispersed by the wind. There is limited information concerning the diversity of TSWV in Southwestern U.S. states and such information is necessary for the development of new TSWV resistant peanut cultivars. Therefore, the objective of this study was to molecularly characterize TSWV-isolates infecting peanut in Texas and Oklahoma. Molecular characterization of the Texas and Oklahoma TSWV isolates indicated that they are distinct from those found in the southeastern United States. Therefore, it is possible that sources of TSWV resistance used to develop cultivars in the southeast may not be effective in the southwest. This knowledge of the diversity of TSWV-isolates in particular region will aid benefit plant breeders in developing new resistant cultivars which can be grown by farmers. Such cultivars will lead to minimal yield losses due to viral infection.
Technical Abstract: Tomato Spotted Wilt Virus (TSWV) is among the greatest yield-reducing viruses affecting peanut (Arachis hypogaea L.) in all peanut-producing states in US. Due to the lack of molecular information on TSWV-isolates that are associated with peanut in the Southwestern states, the aim of this study was to explore their diversity. Symptomatic peanut samples were collected from peanut fields and the virus isolates were characterized. Nonstructural NSm genes and nucleocapsid N genes were amplified by reverse transcriptase–polymerase chain reaction (RT-PCR), cloned, and sequenced, and their phylogenetic relationship was determined. The Clustal W program was used for sequence comparison among TSWV-isolates. Based on nucleotide and amino acid sequences of NSm and N gene proteins, phylogenetic analysis revealed that TSWV isolates from Southwestern U.S. formed close clusters that were distinct from other TSWV isolates reported previously.