Reduction of pith maceration by erwinia chrysanthemi in chrysanthemum cuttings infected with chrysanthemum stunt viroid chrysanthemum morifolium cultivar bonnie jean
Silvergate, A.F.; Dickey, R.S.; Horst, R.K.
Phytopathology 70(2): 135-139
ISSN/ISBN: 0031-949X Accession: 006279953
Cuttings of C. morifolium 'Bonnie Jean,' either healthy or artificially infected with chrysanthemum stunt viroid (CSV), were dip-inoculated with E. chrysanthemi strain 159. Infection by CSV reduced the amount of bacterial pith maceratin, which was determined by measuring the length of maceration from the base of the cutting. A decrease in maceration coincided with the occurrence of viroid symptoms on the leaves and/or the detection of CSV RNA by polyacrylamide gel electrophoresis. Differences between healthy and CSV-infected stems were not noted by histological examination 10-41 days after inoculation with CSV. E. chrysanthemi was restricted to xylem vessel elements in CSV-infected cuttings 5 days after inoculation with the bacterium, whereas bacteria spread from the vessel elements to the adjacent vascular cells and into the pith tissue of healthy cuttings.