Identification of QTL for resistance to plum pox virus strains M and D in Lito and Harcot apricot cultivars

Abstract

Sharka is a severe apricot viral disease caused by the plum pox virus (PPV) and is responsible for large crop losses in many countries. Among the known PPV strains, both PPV-D (Dideron) and PPV-M (Marcus) are virulent in apricot, the latter being the most threatening. An F1 apricot progeny derived from Lito, described in the literature as resistant, crossed to the susceptible selection BO81604311 (San Castrese 9 Reale di Imola) was used to study the genetic control of resistance to PPV. A population of 118 individuals was phenotyped by inoculating both PPV-D and PPV-M strains in replicated seedlings and scored for 3 years. An additional set of 231 seedlings from the same cross was also phenotyped for 2 years. SSRbased linkage maps were used for quantitative trait locus (QTL) analysis. A major QTL of resistance to both PPV-M and PPV-D strains was found in the top half of the Lito linkage group 1, where a QTL was previously described in Stark Earli-Orange, the donor of Lito resistance. The LOD score was considerably enhanced when the recovery of plants from infection was taken into account. The results obtained in Lito were compared with those observed in a second apricot cross progeny (Harcot 9 Reale di Imola) in which QTL of resistance to sharka were also mapped in the same linkage group 1 for both PPV strains. Several models of resistance to sharka disease are discussed considering the segregation frequencies, the QTL alignment in the two maps and the information gathered from the literature.

Evaluation of Turkish apricot germplasm using SSR markers: Genetic diversity assessment and search for Plum pox virus resistance alleles

“…Several molecular markers were placed close to the major locus (Dondini et al, 2011;Vera-Ruiz et al, 2011;Soriano et al, 2012). The SSRs close to PPVres loci does not guarantee the resistance behavior of the apricot cultivar although they are located close to the PPVres loci.…”

“…Due to the difficulties associated with woody plant breeding, the development of resistance-related molecular markers to be used in marker-assisted selection (MAS) has become of vital importance. Genetics maps of apricots have been developed for PPV resistance (Hurtado et al, 2002;Lambert et al, 2007;Soriano et al, 2008;Lalli et al, 2008;Marandel et al, 2009;Pilarová et al, 2010;Dondini et al, 2011;Vera Ruiz et al, 2011) and resistance-related molecular markers were searched. A http://dx.doi.org/10.1016/j.scienta.2015.07.012 0304-4238/© 2015 Elsevier B.V. All rights reserved.…”

Genetic Apricot Resources and their Utilisation in Breeding

“…LG1 (just like in "Stark Early Orange") and when the resistant, tolerant and recovered seedlings were pooled together, the ratio of these to susceptible plants was fixed as 1:1, explaining why such a large part of the phenotypic variability is accounted for by a single QTL in the LG1 [45].…”

“…Dodini et al [45] introduced a potentially different QTL which either explained a very small part of the variance or was below the LOD threshold. The markers closer to the QTL peaks would already be suitable for marker-assisted breeding.…”

Identification of a major QTL for Xanthomonas arboricola pv. pruni resistance in apricot

“…Resistance against sharka in peach, apricot, and Prunus davidiana has been extensively investigated and a major QTL has been found on linkage group (LG) 1 Decroocq et al 2005;Sicard et al 2008;Soriano et al 2008;Dondini et al 2010;Vera Ruiz et al 2011). Other resistance QTLs from P. davidiana have been detected for powdery mildew in peach × P. davidiana crosses on LG1, LG2, LG3, LG5, LG6, and LG8 (Dirlewanger et al 1996;Foulongne et al 2003) and for leaf curl caused by Taphrina deformans in a peach × P. davidiana cross on six linkage groups .…”