Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2008
Publication Date: 5/4/2009
Publication URL: www.actahort.org/books/825/825_21.htm
Citation: Karayiannis,, I., Ledbetter, C.A. 2009. Susceptibility of certain apricot and plumcot cultivars to plum pox virus infection. Acta Horticulturae. (ISHS)825:153-156. Interpretive Summary: Sharka disease, caused by Plum pox potyvirus (PPV), has caused a devastating economic impact for apricot and plum growers as it spread throughout the European and Mediterranean growing regions during the 20th century. PPV has been further introduced to apricot and plum growing regions far from the European continent through as yet undetermined means. Research has now demonstrated that specific apricot cultivars of American origin are resistant to PPV, and the PPV resistance can be transmitted to new apricot varieties through classical breeding. While PPV resistance in plums is very rare, it is possible to hybridize apricots with plums through cross-pollination. PPV resistant plum-apricot hybrids would be possible, given that the apricot used in the pollinations was PPV resistant. We examined numerous previously untested apricots and plum-apricot hybrids for their reaction to both artificial and natural inoculation with PPV. During five years of successive symptom evaluations, we demonstrated that all of the examined plum-apricot hybrids and the majority of the apricots were susceptible to PPV. Apricot cultivar Robada remained free of PPV symptoms 5 years after planting in an orchard with severe PPV pressure. These results will impact positively with California’s growers of Robada apricot, as they will be prepared with a PPV resistant orchard when and if PPV arrives in the California growing regions.
Technical Abstract: The purpose of this research was to investigate new genetic resources for resistance to Sharka disease, which is caused by Plum pox potyvirus (PPV). Sharka disease is threatening the apricot and plum industries of most European and Mediterranean countries. In apricot, PPV resistance to date has only been identified in a small number of cultivars of American origin, which have been used in Greece as parents in crosses with local cultivars. New genetic material created at the USDA/Agricultural Research Service in Parlier, California was examined for reaction to PPV after artificial inoculations by grafting and in conditions of natural virus transmission by the aphid vectors present in the field. Four trees from each of seven apricot cultivars, seven plumcots, one Pluot and one Aprium were planted at the NAGREF-Pomology Institute experimental orchard, where Sharka disease is endemic, in February 1994. All plumcot accessions were found heavily PPV infected by the third year after planting, with very severe disease symptoms. The Aprium and Pluot also demonstrated a severe susceptibility to the disease. Among the apricots examined, only Robada and Havecot have escaped disease in the field.