Citrus psorosis and citrus ringspot diseases could be associated with strains of a common virus
Studies have been carried out in Spain on the possible relationships between citrus psorosis (A and B) and citrus ringspot diseases (EU II/A1). It may be noted that some authors already consider that citrus psorosis B and citrus ringspot are synonyms. By using serologically specific electron microscopy (SSEM - with an antiserum to citrus ringspot), filamentous particles of unusual morphology, previously associated with several ringspot isolates, have also been detected for the first time in psorosis A and psorosis B isolates. In addition, purification studies were carried out with several isolates (15) of citrus ringspot, psorosis A and B, and showed that a specific protein of 47 kDa was detected in most cases, but two isolates (one psorosis A and one ringspot) had a 46 and 48 kDa-protein respectively. However, the three types of protein were serologically related in Western blot. The authors felt that despite some variation in size, the detection a specific protein associated with psorosis and ringspot diseases supports the idea that such protein could be the capsid protein of a virus involved in both diseases. This idea is also supported by the similarity of symptoms induced by psorosis and ringspot, and the detection of unusual particles in all cases. However, biological diversity observed among isolates, difference in the number of particles detected by SSEM, size variation of the putative coat protein strongly suggest that different virus strains may be involved in the citrus psorosis and ringspot diseases.
Sources
Navas-Castillo, J.; Moreno, P. (1995) Filamentous flexuous particles and serologically related proteins of variable size associated with citrus psorosis and ringspot diseases.
European Journal of Plant Pathology, 101(3), 343-348.