Detection of Prunus Necrotic Ringspot and Prune Dwarf Viruses inPrunusSeed and Seedlings by Enzyme-Linked Immunosorbent Assay

Abstract

Enzyme-linked immunosorbent assay (ELISA) was used to determine the incidence of Prunus necrotic ringspot (NRSV) and prune dwarf (PDV) viruses, in lots of Prunus seed and seedlings used by commercial nurseries in Washington and Montana [USA], in 1981-1983. These viruses were found rarely, if ever, in seed or seedlings of P. armeniaca, P. besseyi, P. salicina, P. serotina and P. tomentosa. The incidence of both viruses in noncertified P. mahaleb seed lots (both foreign and domestic) was below the 5% tolerance limit allowed by the tree fruit virus certification programs of both states. Although NRSV was rarely detected in P. cerasifera seed, the incidence of PDV in noncertified seed lots ranged 1-53%. PDV was detected in only 2 of 1000 P. cerasifera seedlings, however, indicating that most PDV-infected seed did not germinate. In noncertified P. avium seed lots, the incidence of PDV ranged 0-58% and the incidence of NRSV ranged 0-28%. The incidence of either virus in P. avium seedlings was dependent on the incidence found in the seed lots. Only an occasional virus-infected seed was found in noncertified P. persica seed lots from Europe, whereas the average incidence of PDV and NRSV in domestic seed lots was 10 and 17%, respectively. Although NRSV was detected in P. persica seedlings of various size classes and in ungerminated seed, PDV was detected only in ungerminated or partially germinated seed. Use of ELISA to monitor virus incidence in Prunus seed and seedlings provides nurseries with a valuable tool for reducing the incidence of seed-borne viruses in Prunus rootstocks.