ISHS Acta Horticulturae 482: International Symposium on Cut Flowers in the Tropics
STUDY OF VASCULAR ROOT RESPONSES AS DEFENSE MECHANISMS IN CARNATION RESISTANT OR SUSCEPTIBLE TO FUSARIUM OXYSPORUM F. SP. DIANTHI BY TRANSMISSION ELECTRON MICROSCOPY |
| Authors: | B.L. Higuera, F. Ebrahim-Nesbat |
| Keywords: | Dianthus caryophyllus, vascular wilting, resistance |
| Abstract:
Roots of carnation (Dianthus caryophyllus L.) seedlings cv. Rosana (susceptible) and cv. Candy (resistant) were inoculated with Fusarium oxysporum f. sp. dianthi. One, two, and 18 days after inoculation (dpi) the infected root tissues were examined by light and electron microscopy and compared with water-treated controls. The study of thin sections of susceptible and resistant cultivars showed numerous fungal hyphae in vascular vessels (xylem) 18 dpi. In control sections the xylem tissue was contaminated with bacteria in both cvs. Rosana and Candy. At ultrastructural level, no defense reaction could be seen in susceptible cv. Rosana. Host reaction of the resistant cv. Candy consisted of an accumulation of osmiophilic material and deposition of electron dense material in the xylem tissue, separation of plasma membranes from the cell walls of adjacent cells and breakdown of the plasma membrane, indicating the expression of an induced defense mechanism in cv. Candy infected with Fusarium oxysporum f. sp. dianthi. | |
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