TheArabidopsispeptide kiss of death is an inducer of programmed cell death

Abstract

Programmed cell death (PCD) has a key role in defence and development of all multicellular organisms. In plants, there is a large gap in our knowledge of the molecular machinery involved at the various stages of PCD, especially the early steps. Here, we identify kiss of death (KOD) encoding a 25-amino-acid peptide that activates a PCD pathway in Arabidopsis thaliana. Two mutant alleles of KOD exhibited a reduced PCD of the suspensor, a single file of cells that support embryo development, and a reduced PCD of root hairs after a 55°C heat shock. KOD expression was found to be inducible by biotic and abiotic stresses. Furthermore, KOD expression was sufficient to cause death in leaves or seedlings and to activate caspase-like activities. In addition, KOD-induced PCD required light in leaves and was repressed by the PCD-suppressor genes AtBax inhibitor 1 and p35. KOD expression resulted in depolarization of the mitochondrial membrane, placing KOD above mitochondria dysfunction, an early step in plant PCD. A KOD∷GFP fusion, however, localized in the cytosol of cells and not mitochondria.

Plantation Forestry under Global Warming: Hybrid Poplars with Improved Thermotolerance Provide New Insights on the in Vivo Function of Small Heat Shock Protein Chaperones

“…To protect cell function, plants have evolved a complex metabolic adjustment process known as the heat shock response (HSR; Kotak et al, 2007;Mittler at al., 2012). Alternatively, programmed cell death is activated in specific cells, resulting in leaf shedding or abortion of reproductive organs (Qu et al, 2009;Blanvillain et al, 2011). Whereas research in forest trees remains scarce, the ubiquitous and conserved HSR has been thoroughly studied in herbaceous plants (Larkindale and Vierling, 2008;Hu et al, 2009;Finka et al, 2011;Mittler et al, 2012).…”

Mechanical stress mediated by both endosperm softening and embryo growth underlies endosperm elimination in Arabidopsis seeds

“…Cell death markers show ZOU-dependent expression in the developing endosperm during seed development Cell death in the developing Arabidopsis seed is not restricted to the endosperm, and is also known to occur in the developing seed coat (Andeme Ondzighi et al, 2008;Nakaune et al, 2005) and the embryonic suspensor (Blanvillain et al, 2011). To identify cell death markers with relative specificity for the endosperm, we therefore interrogated available in silico resources and the literature.…”

The Plant Peptidome: An Expanding Repertoire of Structural Features and Biological Functions

“…In vivo translational GFP fusions showed that the initiation codon of KOD can be recognized for translation in planta, though it remains unclear how the KOD peptide is translated, similar as for PLS (Figure 4). Nevertheless, NMR studies on synthetic KOD peptide pointed out that it adopts an a-helix (from Pro-9 to Arg-21), whereas the N-terminal region is disordered (Blanvillain et al, 2011).…”

“…KOD is encoded by the longest and last ORF in a short KOD-transcript containing three sORFs in sense. Experiments using knockout mutants, carrying a T-DNA insertion and a point mutation (Pro-9 to Ser), respectively, and transient assays in onion (Allium cepa) using mutated and truncated variants of KOD indicate that KOD functions as a peptide rather than as RNA (Blanvillain et al, 2011). In vivo translational GFP fusions showed that the initiation codon of KOD can be recognized for translation in planta, though it remains unclear how the KOD peptide is translated, similar as for PLS (Figure 4).…”

“…KOD is a 25-amino acid peptide unique in Arabidopsis and involved in programmed cell death regulation (Blanvillain et al, 2011). More specifically, it modulates suspensor elimination during embryogenesis and root hair programmed cell death.…”