EFFECT OF TMV INDUCED SYSTEMIC ACQUIRED-RESISTANCE AND REMOVAL OF THE TERMINAL BUD ON MEMBRANE-LIPIDS OF TOBACCO-LEAVES

Significant alterations in lipid composition of leaf tissues occured only as a consequence of depletion. In the remaining leaves of decapitated plants an increase in phospholipid content and in the phospholipid/sterol molar ratio as well as an enhanced resistance to a non-host-specific toxin (fusaric acid) in ion leakage test suggest that the induction of resistance to TMV coincides with rejuvenation of leaf tissue. The phospholipid/sterol vesicles obtained from decapitated plants were more fluid than those from control plants, as measured by the diphenylhexatriene (DPH) fluorescence polarization technique (PDPH). In contrast, the changes in membrane lipids in leaves with SAR were statistically not significant. The degree of unsaturation of fatty acids in polar lipids did not change either in decapitated or in plants with SAR. The possible significance of these results is discussed in terms of oxyradical mediated mechanisms leading to tissue necrosis during hypersensitive reaction (HR). © 1990.