Acta Univ Latv (2003) 662: 51–58

Changes of the secretory system of leaf epidermal and mesophyll cells during stress and programmed cell death

Abstract

Comparison was made between the effects of ethylene-induced programmed cell death and leaf senescence-caused programmed cell death on the Golgi apparatus and secretory pathway in tobacco leaves. Transgenic tobacco (Nicotiana tabacum L.) plants containing jellyfish green fluorescent protein (GFP) fused to rat sialyltransferase located in Golgi bodies and endoplasmic reticulum were used. Forty-day old plants were sprayed with Ethephon at concentrations of 5 × 10-3 M or 5 × 10-2 M. We observed cells from intact leaves and leaf sections cultivated in medium. Intact control plants and sections from expanding and mature leaves cultivated in Murashige and Skoog basal medium showed a high number of vectorially moving and oscillating Golgi bodies. Programmed cell death caused by leaf senescence or induced by Ethephon treatment caused a decrease of GFP fluorescence. Golgi bodies were located in the basal part of palisade parenchyma cells in senescent leaves but Ethephon treatment caused an increase of the number of Golgi bodies in the apical part of palisade parenchyma cells.