Prevalence and distribution of peach yellow leaf roll in north of Iran.

Abstract

In the growing season of 2012, a phytoplasma-like disease was observed on peach and nectarine plants (Prunus persica) in several locations in the Iranian provinces of Mazandaran and Golestan. Affected trees were stunted, had upward curled and thickened leaves with purple-colored margins of their adaxial surface, and showed also a weak shoot growth. Vegetating shoots were collected from 25 symptomatic and three symptomless trees from whose leaf midribs and petioles DNA was extracted following the procedure of Zhang et al. (1998). Fragments of the rRNA operon were amplified using the phytoplasma primer pair P1/P7 followed by R16F2n/R16R2 for nested PCR (Gundersen and Lee 1996). A 1200 bp product was amplified from all symptomatic samples but not from any of the symptomless trees. PCR products of four isolates were sequenced and deposited in GenBank with accession Nos. KC751538, KF739407, KF739408 and KF923872. Blast comparison of these sequences revealed the highest identity of all four isolates (99%) with those of members of the 16SrXII group 'Candidatus Phytoplasma solani' (Quaglino et al., 2013). This phytoplasma has previously been reported, along with 'Ca. P. aurantifolia' and 'Ca. P. trifolii', as the agent associated with yellow leaf roll-diseased peach in the central provinces of Iran (Zirak et al., 2010). The distribution of 'Ca. P. solani' is now extended to the three major northern Iranian provinces, where it appears to be the prevailing phytoplasma species