Genetic characterization and mapping of major gene resistance to potato leafroll virus in Solanum tuberosum ssp. andigena

Abstract

Major gene inheritance of resistance to Potato leafroll virus (PLRV) was demonstrated in a parthenogenic population derived from the highly resistant tetraploid andigena landrace, LOP-868. This major gene or chromosome region seems to control a single mechanism for resistance to infection and virus accumulation in this source. About 149 dihaploid lines segregated in a ratio of 107 resistant to 32 susceptible, fitting the expected ratio for inheritance of a duplex gene under random chromatid segregation. A tetraploid AFLP map was constructed using as reference the ultra high density (UHD) map. All AFLP markers associated with PLRV resistance mapped to the same linkage group. Map position was confirmed by analysis of previously-mapped SSR markers. Rl (adg) is located on the upper arm of chromosome V, at 1 cM from its most closely linked AFLP marker, E35M48.192. This marker will be used to develop allele-specific primers or a pair of flanking PCR-based markers for their use in marker assisted selection.

Introgression of the Rl adg allele of resistance to potato leafroll virus in Solanum tuberosum L.

“…The cultivars Perricholi and LOP-868 have been used as controls to evaluate resistance to PLRV due to the absence or presence of the Rl adg allele, respectively (Velásquez et al 2007, Mihovilovich et al 2014.…”

“…Other works, such as that of Velásquez et al (2007) and Mihovilovich et al (2014), who used PLRV inoculation by means of viruliferous aphids, adopted the DAS-ELISA serological test only at 40 DAI, which is enough time for the test to accurately detect the presence or absence of PLRV in the plant. Beekman (1987) states that resistance to infection is highly dependent on inoculum pressure, which is governed by the population levels of vector aphids.…”

“…This was the case of some treatments identified as possible false positives in the work of Mihovilovich et al (2014). Even with the Rl adg allele, PLRV infection can occur and reach levels of up to 20% in LOP 868 when virus pressure is high (Velásquez et al 2007). …”

“…However, even with the polygenic control, Velásquez et al (2007) have demonstrated the existence of a major gene or a genomic region, Rl adg , which controls a single mechanism of resistance to the infection and to PLRV accumulation. The cultivar LOP-868 (S. tuberosum ssp.…”

“…The cultivar LOP-868 (S. tuberosum ssp. andigena) has been mentioned in countless studies as an interesting source of resistance to PLRV, presenting the Rl adg gene in the duplex condition , Velásquez et al 2007, Mihovilovich et al 2014). Nevertheless, due to the binding of genes that confer resistance to PLRV to undesirable traits, such as irregular shape, small tubers, and low yield (Barker and Harrison 1985), the commercialization of the tubers of this cultivar becomes impracticable.…”