ARS | Publication request: Identification of putative peanut TSWV resistance gene(s) and development of markers for breeding

Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: June 15, 2009
Publication Date: July 5, 2009
Citation: Chen, X. Culbreath, A. Brenneman, T. Holbrook, Jr. C.C. Guo, B. 2009. Identification of putative peanut TSWV resistance gene(s) and development of markers for breeding. American Peanut Research and Education Society Abstracts. Presented at the APRES annual meeting, July 14-17, 2009 in Raleigh, N.C.

Technical Abstract: The most promising solution for managing tomato spotted wilt virus (TSWV) is development of resistant cultivars. However, practicable markers and resistance genes in peanut have not been identified yet due to lack of genomic resources. Resistance genes to TSWV have been found in tomato and pepper, named Sw-5 and Tsw, respectively. We have discovered 41 gene fragments originally from peanut expressed sequence tags (ESTs) with significant homology to two tomato BAC sequences (AY007366 and AY007367), which spanned 5 different resistance candidate sequences. Reverse northern-blots have identified eighteen clones with significant levels of expression. Out of these clones, we identified one, named Ahsw, with approximately 37% of amino acid identity to tomato Sw-a. Southern blot indicated that there are at least 4 copies of Ahsw gene in the cultivated peanut genome. Two full-length Ahsw cDNAs, Ahsw-a (1827 bp) and Ahsw-b (2193 bp) with 94% of similarity to each other, have been identified using 5’- and 3’-RACE (Rapid Amplification of cDNA Ends). Using a fragment of Ahsw as probe, three restriction enzymes, HindIII, EcoRI and RsaI, were used to examine the Restriction Fragment Length Polymorphism (RFLP). The results showed that different number and length of restriction fragments were observed in different genotypes (Tifrunner, GT-C20, SunOleic 97R, NC94022), suggesting its potential use as a marker. Two mapping populations have been developed. A total of 96 leaf DNA samples of F4s from the two populations were used for RFLP analysis with HindIII. The results showed that segregation really occurred for both of the two populations. The RFLP will be converted to PCR-based markers. Northern blots revealed different expression patterns of Ahsw, but further experiments are needed to confirm an association of this gene with resistance to TSWV.