Detection and Molecular Characterization of Phytoplasmas Associated with Pome Fruits in Northwest Iran

Phytoplasmas are a group of plant pathogenic mollicutes belonging to the family Acholeplasmataceae, which are limited to phloem in their plant hosts and are associated with a variety of diseases in a wide range of plants. To detect and characterize phytoplasma(s) presence in apple, pear and quince fruits in the main pome fruits producing areas in Northwest Iran (Zanjan, East Azarbayjan and West Azarbaijan provinces), a total of 56 symptomatic samples were collected. Field surveys conducted in 2020 and 2021 identified symptomatic trees showing small leaves, leaf reddening, yellowing, rolling, scorching, witches’ broom, leading to gradual death of the trees. PCR analysis using phytoplasma universal primers showed phytoplasmas presence in surveyed area. The phytoplasmas detected in symptomatic pears were identified as ‘Candidatus Phytoplasma pyri’ and ‘Ca. P. asteris’, members of the apple proliferation subgroup (16SrX-C) and aster yellows subgroup (16SrI), respectively. ‘Ca. P. trifolii’ belonging to the clover proliferation group (16SrVI) and ‘Ca. Phytoplasma prunorum’ (16SrX-B) detected in quince and apple symptomatic samples, respectively. This is the first report of ‘Ca. P. trifolii’ presence in quince, and of ‘Ca. P. prunorum’ in apple in Iran. These findings underscore the critical need for targeted phytoplasma monitoring and management strategies in Iran’s pome fruit orchards to mitigate disease spread and protect agricultural productivity.