Quantitative trait loci meta‐analysis of Plum pox virus resistance in apricot (Prunus armeniaca L.): new insights on the organization and the identification of genomic resistance factors

Abstract

Plum pox virus (PPV) is responsible for sharka disease, one of the most detrimental stone fruit diseases affecting Prunus trees worldwide. Only a few apricot cultivars have been described as resistant, most originating from North American breeding programmes. Several PPV resistance quantitative trait loci (QTLs) have been mapped in various progenies, consistently highlighting the contribution to the resistance of the upper part of linkage group 1 (LG1). However, to date, no consensus has been reached on the precise number of QTLs linked to the resistance to PPV in apricot and P. davidiana or on their accurate position on the genetic linkage map. In the present study, the quantitative resistance of cultivar 'Harlayne' was analysed over five growth periods in a large F1 population. Four QTLs were identified, three mapping on LG1, explaining between 5% and 39% of the observed phenotypic variance. In an effort to further this analysis of PPV resistance in apricot, these results were merged in a single QTL meta-analysis with those of five other PPV resistance analyses available in the literature. Three consensus QTL regions were identified on LG1 and a putative fourth region on LG3. QTL meta-analysis also revealed the contribution of each resistant cultivar to metaQTLs, providing interesting comparative data on the resistance factors shared between the resistance sources used in the various studies. Finally, it was shown that one of the metaQTLs co-localizes with the eukaryotic translation initiation factor eIF4E, thus providing new hypotheses on the mechanisms of PPV resistance in apricot.

Meta-analysis of QTLs Involved in Pre-harvest Sprouting Tolerance and Dormancy in Bread Wheat

“…Meta-QTL analysis has also been successfully conducted in several other crops like maize Truntzler et al, 2010;Hao et al, 2010;Li et al, 2011;Wang et al, 2006;Coque et al, 2008), cotton (Rong et al, 2007), rice (Ballini et al, 2008;Norton et al, 2008;Khowaja et al, 2009), rapeseed (Shi et al, 2009), potato (Danan et al, 2011), cocoa (Lanaud et al, 2009), soybean (Guo et al, 2006;Sun et al, 2012) and apricot (Marandel et al, 2009). …”

Biological evidence for practical immunity of apricot cultivar Harlayne to Plum pox virus

“…Harlayne four distinct dominant resistance QTLs, three on linkage group 1 (LG 1) and one QTL on LG 3. Molecular studies of Marandel et al (2009) proved different PPV behaviour of cv. Harlayne from other PPV resistant apricot cultivars.…”

“…This conclusion is in agreement with the fact that Sicard et al (2008) experimented with apricot cv. Goldrich, susceptible to PPV-M. Only Marandel et al (2009) used in molecular studies of PPV resistance quantitative trait loci (QTLs) not only apricot cvs SEO and Goldrich but also cv. Harlayne.…”

Genetic Apricot Resources and their Utilisation in Breeding

“…Four quantitative trait loci (QTLs) were identified of which three mapped on linkage group 1 (LG1) which explained between 5 and 39% of the phenotypic variance. This happened when analyzing quantitative resistance of Harlayne cultivar in a large F1 population [44]. Dondini et al established that a major QTL for resistance to both PPV-M and PPV-D strains was found in the top half of "Lito"…”

“…The main QTL on LG1 was upheld by Sicard et al [51] establishing new microsatellite (SSR) markers flanking the QTL and by Lalli et al [52] in a backcross population of SEO 9 Vestar and was again confirmed by Soriano et al [46] in the extended F2 Lito selfed progeny. Most of the resistance determinants shown above were characterized using the PPV-D strain as a source of inoculum and, at present, the only resistances specific to the PPV-M strain are those endorsed in the BC1 SEO xVestar [52] and in P. davidiana [44].…”