Ultrastructure of Citrus Chlorotic Dwarf-Infected Leaves and Bark

D Howd, J Hartung, R Brlansky
2002 unpublished
Citrus chlorotic dwarf (CCD) is a virus-like disease discovered in Turkey in the mid 1980s. Infected plant material was sent to the USDA, ARS exotic citrus quarantine facility in Beltsville, MD and was grafted into Citrus macrophylla seedlings. Symptoms of CCD include various chlorotic patterns and leaf crinkling or other types of distortion. Leaves are small and often have a notch near the apex. Leaves showing symptoms of chlorosis, leaf crinkling and distortion, and bark from the symptomatic
more » ... om the symptomatic shoots were collected and prepared for ultrathin sectioning and transmission electron microscopy. In sections of tissue, high numbers of ribosomes and endoplas-mic reticulum (ER), especially rough ER, were observed in both leaf and bark tissues. Chloro-plasts showed partial to complete breakdown of the grana in all tissues and very little starch was observed. Cellular membranes and cell walls remained intact and most cell contents were recognizable. In bark sections, there were numerous membrane-bound vesicles and some phloem cells were found to contain an unknown filamentous material, which appeared virus-like.