Secretory Activities in Vessel Contact Cells

Secretory activity is triggered off in xylem contact cells when the neighbouring vessels are stressed. The nature and intensity of the secretion depend upon the nature of the stress (wounding, infection with a pathogenic or non-pathogenic vascular parasite). Various metabolites are synthesized, among which carbohydrates and polyphenols are conspicuous. These products can be discharged through the pits into the lining vessels where they produce considerable gummosis. Secretion dynamics were studied in detail in carnation plants.