Incidence and distribution of Apple chlorotic leaf spot virus in the main fruit growing areas of Iran.
A survey for the presence of Apple chlorotic leaf spot virus (ACLSV) in apple (Malus pumila), pear (Pyrus communis) and quince (Cydonia oblonga) was conducted in the provinces of Tehran, Isfahan, Khorasan, East and West Azerbaijan, the main pome fruit growing areas in Iran. Samples were taken from 1078 apple, 92 pear and 23 quince trees and tested by double antibody sandwich-ELISA for the presence of ACLSV using commercial kits (Bioreba, Switzerland). ACLSV was detected in 200 apple samples (18.55%) but in none of the other samples. Some of the positive samples came from trees bearing small and malformed leaves with necrotic lesions, whereas others were from symptomless plants. The highest incidence of ACLSV was in the province of Isfahan (30.9%), followed by West Azerbaijan (17.78%), Tehran (14.1%) and East Azerbaijan (11.68%). To confirm virus identification, total RNA was extracted from leaf samples and subjected to reverse transcription polymerase chain reaction using primers specific for a region of the ACLSV genome that encodes part of the coat protein (CP). A 358 bp DNA fragment corresponding to a fragment of the ACLSV CP gene was amplified from extracts of infected trees but not from those of healthy trees.