Inheritance of resistance to Plum pox virus in apricot (Prunus armeniaca L.)

Abstract

The inheritance of resistance to Plum pox virus (PPV) has been studied in 1,178 apricot hybrids. Seven hundred and eighteen F1 hybrids, obtained from controlled crosses between the susceptible Greek cultivar "Bebecou" and the resistant PPV cultivars of American origin ("Stark Early Orange," 'NJA2," 'Veecot," "Sunglo," "Harlayne," and "Orangered") were evaluated for resistance to the PPV-M (Marcus) strain, 8 years after artificial inoculation. The inheritance of resistance to PPV has been additionally studied for the first time in a BC 1 population of 95 apricot hybrids for four vegetative periods. Reaction of each hybrid to PPV-M was scored through visual symptoms, indexing onto GF-305 and double-antibody sandwich enzyme-linked immunosorbent assay tests. Segregation within the hybrids, determined by Chisquared analysis, fits a 1:1 ratio (P≤0.05) of the resistant vs susceptible, indicating that resistance to PPV is controlled by a single dominant gene locus and that the above six resistant cultivars are heterozygous for the trait. Plants carrying this gene may initially develop disease symptoms on leaves but eventually recover and no virus can be detected in leaves. Susceptible plants show similar symptoms initially but remain symptomatic. Inheritance of resistance to PPV also has been studied in 365 F1 hybrids by crossing the resistant cultivar "Stella" with the susceptible "Bebecou" and the resistant cultivars "Sunglo" and "NJA2," for 8 years after inoculation. The segregation ratio was 1:0 (resistant/susceptible) suggesting that "Stella" is homozygous for the resistance trait. The purpose of this work was the enhancement of the knowledge of inheritance of resistance to PPV for the selection of new cultivars.

Origin of resistance to plum pox virus in Apricot: what new AFLP and targeted SSR data analyses tell

“…This is most likely due to scoring of the resistant genotype. Several studies suggest that the resistance is conferred by a limited number (1-3) of genes (Dicenta et al 2000;Dosba et al 1992;Krška et al 2002;Karayiannis et al 2007;Soriano et al 2007). Nevertheless, in spite of progress in understanding inheritance of PPV resistance, the unknown pedigree of North American cultivars hampers exploitation of the genetic resources of resistance within apricot germplasm.…”

Reaction of an F1 apricot hybrid population to artificial and natural inoculation of Plum pox virus

“…Recovery in a case of progeny derived from 'Stark Early Orange' x 'Bebecou' has been described by Karayiannis et al (2008) who suggested that 'resistance inherited from parent cv. ''Stark Early Orange'' is not ''hypersensitivityrelated'' or ''immunity'' type, but a ''recovery'' from infection'.…”

“…The theory of at least three genes involved was also expressed (Guillet-Bellanger & Audergon 2001;Salava et al 2005). The monogenic hypothesis of resistance fitted better to the observed data (Dicenta et al 2000;Lambert et al 2007;Rubio et al 2007;Karayiannis et al 2008;Soriano et al 2008).…”

Genetic Apricot Resources and their Utilisation in Breeding

“…Badenes et al were the first to suggest the role of Eastern Asiatic species, particularly P. mandshurica, as a potential source of PPV resistance into North American germ-plasm [32]. The results from Karayiannis et al [31,33] gave more support to this idea, even if not all the progenies of P. mandshurica were PPV resistant [34]. North American selections derived from P. mandshurica were introduced for their cold hardiness in midwinter and spring, late blooming and the ability to set fruit under adverse conditions for pollination [35].…”