The role of vacuole in plant cell death

Abstract

Almost all plant cells have large vacuoles that contain both hydrolytic enzymes and a variety of defense proteins. Plants use vacuoles and vacuolar contents for programmed cell death (PCD) in two different ways: for a destructive way and for a nondestructive way. Destruction is caused by vacuolar membrane collapse, followed by the release of vacuolar hydrolytic enzymes into the cytosol, resulting in rapid and direct cell death. The destructive way is effective in the digestion of viruses proliferating in the cytosol, in susceptible cell death induced by fungal toxins, and in developmental cell death to generate integuments (seed coats) and tracheary elements. On the other hand, the non-destructive way involves fusion of the vacuolar and the plasma membrane, which allows vacuolar defense proteins to be discharged into the extracellular space where the bacteria proliferate. Membrane fusion, which is normally suppressed, was triggered in a proteasome-dependent manner. Intriguingly, both ways use enzymes with caspase-like activity; the membrane-fusion system uses proteasome subunit PBA1 with caspase-3-like activity, and the vacuolar-collapse system uses vacuolar processing enzyme (VPE) with caspase-1-like activity. This review summarizes two different ways of vacuole-mediated PCD and discusses how plants use them to attack pathogens that invade unexpectedly.

Leaf Oil Body Functions as a Subcellular Factory for the Production of a Phytoalexin in Arabidopsis

“…They are responsible for the accumulation of stable phytoalexins in dead tissues and fallen leaves, which are unable to generate active defenses. Little is known about immunity in the perilesional area in plants, although immunity in the infected regions is well characterized (Collins et al, 2003;Hatsugai et al, 2004;Lipka et al, 2005;Jones and Dangl, 2006;Stein et al, 2006;Hatsugai et al, 2009;Narusaka et al, 2009;Shirasu, 2009;Hiruma et al, 2010;Hara-Nishimura and Hatsugai, 2011). This study provides a conceptual advance to our understanding of oil body function by revealing a form of perilesional defense in leaf oil bodies that is designed to block the spread of fungi from dead tissues to healthy tissues.…”

Self-Incompatibility-Induced Programmed Cell Death in Field Poppy Pollen Involves Dramatic Acidification of the Incompatible Pollen Tube Cytosol

“…Vacuolar cell death is one of two major classes of PCD in plants . It is thought that collapse of the vacuole is a key irreversible step in several plant PCD systems, including during tissue and organ formation, such as the classic differentiation of tracheary elements (Hara-Nishimura and Hatsugai, 2011). Exactly how this is achieved and what processes are involved remain unknown.…”

Formation of plant tracheary elements in vitro – a review

“…Programmed cell death is initiated by vacuole rupture. The release into the cytosol of hydrolytic enzymes, including deoxyribonucleases (DNases), ribonucleases (RNases) and proteases, leads to the degradation of TE cell contents (Groover et al 1997;Obara et al 2001;Fukuda 2000;Hara-Nishimura and Hatsugai 2011;Fukuda 1997a). The secondary cell-wall patterning during xylem differentiation and the regulation and function of xylem cell death have been reviewed by Oda and Fukuda (2012) and Bollhöner et al (2012) respectively.…”