Peach rosette, little peach, red suture and western X-disease phytoplasmas are closely related
In the eastern part of USA, 4 different phytoplasma diseases of peach have been reported, differing by their symptomatology:
- peach rosette (localized outbreaks have been reported – EPPO A1 list);
- peach yellows (severe outbreaks were reported in the 19th and early 20th but the disease has not been observed since the last 20 years – EPPO A1 list);
- little peach (occasionally found);
- red suture (also occasionally found).
In the western part of USA, peach is affected by 2 other phytoplasma diseases, western X-disease (EPPO A1 list) and peach yellow leaf roll, which are not reported in the eastern part. Comparison studies were done between peach rosette, little peach, and red suture phytoplasmas. The 16S ribosomal DNA fragments (of one isolate for each phytoplasma) were cloned and sequenced. Comparison between these sequences showed more than 99% similarity. In addition, when compared with the published sequence for 16S rDNA of western X-disease phytoplasma, a similarity of more than 99% was also found. The authors concluded that peach rosette, little peach, red suture were induced by a phytoplasma which is closely related to western X-disease phytoplasma. It is also recalled that earlier studies had shown close relationships between peach yellows and western-X disease.
Sources
Scott SW, Zimmerman MT (2001) Peach rosette, little peach and red suture are diseases induced by a phytoplasma closely related to Western X-disease.
Acta Horticulturae no. 550, 351-354.