Marker assisted identification of tospovirus resistant tomato genotypes in segregating progenies

Abstract

The SCAR (Sequence Characterized Amplified Region) 'Sw-421' molecular marker is located at 1.0 cM from the Sw-5 allele, originated from Lycopersicon peruvianum (L.), which confers resistance to the tomato spotted wilt virus (TSWV). However, it had not been tested yet in advanced tomato populations. The goal of this study was to distinguish resistant homozygotes (Sw-5/Sw-5) and heterozygotes (Sw-5/Sw-5 + ) from susceptible (Sw-5 + /Sw-5 + ) plants in crossing populations with the Stevens cultivar and advanced backcrossing populations by using 'Sw421' SCAR marker. The amplification of 940 bp and 900 bp bands characterized the resistant homozygotes and susceptible controls, respectively. A two band pattern (900 bp and 940 bp) was observed in heterozygote genotypes (Sw-5/Sw-5 + ), which confirmed the co-dominant inheritance mechanism of the marker. Fifty seven plants from the isogenic progenies were characterized based on bands pattern: 18 plants (31.6%) were identified as resistant homozygotes, 8 plants (14.0%) as resistant heterozygotes and 31 plants (54.4%) were characterized as susceptible. The SCAR 'Sw-421' marker is an important tool for selection and pyramid resistance alleles, mainly when other resistance sources to the TSWV are available, such as the Rey de los Tempranos source.

A heuristic method of searching for interesting markers in terms of quantitative traits

“…One of the important differences between these two approaches is the inability to localise the interesting marker on a linkage map. Nevertheless, such markers are sufficient for efficiently selecting genotypes with desirable traits, which is the main goal of marker- assisted selection (Martin et al 2008;Pawłowicz et al 2008;do Nascimento et al 2009). Repeatability of the results for a marker across environments suggests its usefulness in a breeding programme.…”