THE INHIBITION OF THE HYPERSENSITIVE RESPONSE OF POTATO-TUBER TISSUESBY CYTOKININS - SIMILARITIES BETWEEN SENESCENCE AND PLANT DEFENSE RESPONSES (VOL 44, PG 33, 1994)
Kb. Beckman et Ds. Ingram, THE INHIBITION OF THE HYPERSENSITIVE RESPONSE OF POTATO-TUBER TISSUESBY CYTOKININS - SIMILARITIES BETWEEN SENESCENCE AND PLANT DEFENSE RESPONSES (VOL 44, PG 33, 1994), Physiological and molecular plant pathology, 45(3), 1994, pp. 229-246
It has been found that cytokinins (CKs) are able to inhibit the hypers
ensitive response (HR) and to induce susceptibility in plants. It has
also been argued that the ability of CKs to delay the senescence of de
tached leaves and flowers may be due to an inhibition of the peroxidat
ion of lipids observed during senescence. Recently, the work of numero
us groups has implicated the peroxidation of lipids in the HR. Therefo
re, it was of interest to investigate the effect of CKs on plant defen
ces further. In this work, the effect of 6-furfurylaminopurine (kineti
n) on the HR of potato tubers challenged with Phytophthora infestans w
as investigated. The characterization of the host-pathogen interaction
was achieved via the measurement of hypersensitive cell death (electr
olyte leakage), secondary defences (phytoalexin accumulation), and fun
gal growth in planta (fungal biomass measured by enzyme-linked immunos
orbent assay). Kinetin inhibited electrolyte leakage at concentrations
from 15-240 mu M, depressed phytoalexin accumulation al 120-240 mu M,
and induced susceptibility at concentrations greater than 60 mu M. In
this regard, kinetin mimics the action of salicylhydroxamic acid, an
inhibitor of CN--insensitive respiration and lipoxygenase. A hypotheti
cal model linking senescence and HR physiology via oxidative damage is
briefly presented.