Colonization and histopathology of susceptible and resistant carnation cultivars infected with Fusarium oxysporum f. sp. dianthi

R.P. Baayen*, D.M. Elgersma

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

42 Citations (Scopus)

Abstract

Stems of the susceptible 'Early Sam' and resistant 'Novada' carnations were inoculated with a conidial suspension of Fusarium oxysporum f. sp. dianthi. Stem segments of either cultivar were sampled regularly and used for determination of fungal growth and for microscopical investigation. 'Early Sam' showed typical Fusarium wilt symptoms and its stems were colonized intensively. The observed vascular browning appeared to be caused by discolouration of primary walls of infected vessels and surrounding cells. Vessels were rarely occluded with gel. Cell wall degradation led to the formation of stem cavities. Hyperplasia of xylem parenchyma was not seen. In 'Novada', fungal colonization remained low throughout the experiment. Macroscopic symptoms were absent except for longitudinal bursts in the stem, which appeared to be caused by hyperplasia of xylem parenchyma bordering infection. Vascular gelation occurred in the infected tissues, causing some vascular browning also. Xylem vessel regeneration was observed in the hyperplastic layer. Cavities were not formed, and wall discolouration was rare. Vascular gelation is considered part of the Fusarium wilt resistance mechanism. It is followed by xylem vessel regeneration, which expresses a general plant response to vascular dysfunction rather than being part of the resistance mechanism. Although of different origin, vascular browning as such occurs in both susceptible and resistant interactions. In breeding for resistance, care should hence be taken with the current use of browning as an indication of disease.

Original languageEnglish
Pages (from-to)119-135
Number of pages17
JournalNetherlands Journal of Plant Pathology
Volume91
Issue number3
DOIs
Publication statusPublished - May 1985
Externally publishedYes

Keywords

  • Dianthus caryophyllus
  • gel formation
  • resistance mechanism
  • vascular browning
  • vessel regeneration

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