Plant cells show an acquired insensitivity to Brefeldin A

Abstract

Hawes, 1993). Often these compartments are surrounded by remnants of Golgi stacks, where the trans-cisternum The parameters of Brefeldin A (BFA) action in plant faces into the BFA compartment, suggesting that vesiculacells have been further investigated in maize root tips. tion of the stack is a controlled event. These BFA Incubation of maize root tip cells with 100 m gm l’1 BFA compartments can be specifically and heavily stained for for 2 h induces the vesiculation and aggregation of secretory products, indicating an accumulation of secretGolgi membrane to form BFA compartments; an effect ory products at the Golgi after BFA treatment (Satiatthat is reversed by incubation of the cells in BFA-free Jeunemaitre and Hawes, 1993). medium. In this paper, the effects of prolonged incuba- For the majority of plant cell types investigated, a tion with BFA are reported, revealing that Golgi stacks response to BFA has been observed. Reported ultrastrucspontaneously re-form in the presence of this drug tural eVects include an increase in cisternal length after incubation for 12 h or 24 h. The observation that ( Kimura et al., 1993; Yasuhara et al., 1995), or reduction the same BFA solution is still able to induce the forma- in the number of cisternae per stack (Schindler et al., tion of BFA compartments in fresh roots suggests that 1994), and vesiculation of the trans -o rcis-cisternae this recovery is not due to metabolism, detoxification (Satiat-Jeunemaitre and Hawes, 1992; Driouich et al., or depletion of the drug. Furthermore, incubation of 1993; Kimura et al., 1993; Rutten and Knuiman, 1993; maize roots with a fresh 100 m gm l’1 BFA solution for Schindler et al., 1994; Dairman et al., 1995). The well2 h following 24 h BFA treatment fails to induce the documented response of mammalian cells to BFA, the reformation of BFA compartments. Thus, an acquired retrograde adsorption of Golgi proteins into the endoinsensitivity to BFA in plant cells, that has not been plasmic reticulum (Lippincot-Schwartz et al., 1989) may observed in mammalian cells to date, is indicated. occur in some plant cell types. ER-Golgi connections