First report of Peach Latent Mosaic Viroid in symptomatic peach orchards in Southern Bulgaria
Viroids are plant infectious agents whose genome is represented by a small (246 to 401 bp), single-stranded, circular, non-coding RNA capable of autonomous replication in susceptible hosts. Peach latent mosaic viroid (PLMVd) causes a wide variety of peach symptoms, some of which are barely noticeable, while others such as mosaic or chlorotic spots on leaves or fruit tissue, even more severe like albino phenotype (calico peach) are well distinguishable. Changes in the appearance of the fruit and
... the reduction in the lifespan of peach trees cause serious economic losses. In the present work, we study the occurence of PLMVd in peach orchards, located in Plovdiv region. In two successive vegetations (2019-2020) leaf samples from 4-10-years-old peach trees of cvs. 'Royal Gem' and 'Gergana', manifesting chlorosis or mosaic on leaves and/or pale areas on the skin of ripe fruits, symptoms potentially caused by PLMVd, were selected for RT-PCR analysis. PLMVd specific amplification product of approximately 348 bp was obtained from cv. Royal Gem. The amplicon was directly sequenced and presence of PLMVd was proved. Buds of PLMVd infected peach were grafted on the indicator GF 305, peach cultivar "Summerset" (Prunus persica) and myrobalan (Prunus cerasifera). Prior to grafting, the experimental plants were serologically tested by ELISA for the presence of ACLSV, PPV, PNRSV and PDV. Four weeks post inoculation, the grafted plants developed a PLMVd-specific phenotype. The presence of PLMVd in the inoculated plants was confirmed. To our knowledge, this is the first report of PLMVd on peach in Bulgaria.