Programmed cell death in cereal aleurone

Fath, Angelika; Bethke, Paul C.; Lonsdale, Jennifer E.; Meza-Romero, Roberto; Jones, R. L.

doi:10.1007/978-94-010-0934-8_2

Cited by 63 publications

(89 citation statements)

References 58 publications

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“…Upon seed germination, aleurone cells secrete hydrolytic enzymes that break down and mobilise the reserves accumulated in the dead starchy endosperm. 51,52 Recommendations to Authors, Reviewers and Editors of Scientific Journals…”

Section: Mixed and Atypical Modalities Of Plant Cell Deathmentioning

confidence: 99%

Morphological classification of plant cell deaths

et al. 2011

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Programmed cell death (PCD) is an integral part of plant development and of responses to abiotic stress or pathogens. Although the morphology of plant PCD is, in some cases, well characterised and molecular mechanisms controlling plant PCD are beginning to emerge, there is still confusion about the classification of PCD in plants. Here we suggest a classification based on morphological criteria. According to this classification, the use of the term 'apoptosis' is not justified in plants, but at least two classes of PCD can be distinguished: vacuolar cell death and necrosis. During vacuolar cell death, the cell contents are removed by a combination of autophagy-like process and release of hydrolases from collapsed lytic vacuoles. Necrosis is characterised by early rupture of the plasma membrane, shrinkage of the protoplast and absence of vacuolar cell death features. Vacuolar cell death is common during tissue and organ formation and elimination, whereas necrosis is typically found under abiotic stress. Some examples of plant PCD cannot be ascribed to either major class and are therefore classified as separate modalities. These are PCD associated with the hypersensitive response to biotrophic pathogens, which can express features of both necrosis and vacuolar cell death, PCD in starchy cereal endosperm and during self-incompatibility. The present classification is not static, but will be subject to further revision, especially when specific biochemical pathways are better defined. Research on plant cell death has grown considerably in the past few years, owing to the importance of cell death for plant development and defense. Just as animal cells engage several mechanisms leading to death, the road to cell demise in plants can also vary. The long evolutionary distance and distinct cellular architecture between the two kingdoms may account for the differences between the mechanisms of plant and animal cell death. It is therefore appropriate to assess the relevance of animal cell death nomenclature 1 to plants. At present, there is confusion in cell death terminology in plant biology, which drives our attempt to formulate a more logical classification. Although our molecular understanding of plant cell death regulation and execution is insufficient to create definitive classifications based on precise biochemical pathways, it is possible to begin classifying plant cell death scenarios based on morphological criteria, as was initially the case in animal cell death research 2,3 and is still used for the classification of cell death in animal science. 1 This document attempts to provide a classification of plant cell death. We urge authors, reviewers and editors to follow this classification to facilitate communication between scientists and accelerate research in this field.

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Section: Mixed and Atypical Modalities Of Plant Cell Deathmentioning

confidence: 99%

Morphological classification of plant cell deaths

et al. 2011

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“…Barley LTP1 is synthesized in the aleurone (38), whereas lipids and enzymes are located in the embryo (37). During germination, a cell decompartmentalization occurs, controlled by programmed cell death (39), that allows LTP1 adduction.…”

Section: Barley Ltp1 Specifically Traps the Unstable Allene Oxide 9(smentioning

confidence: 99%

Specific Adduction of Plant Lipid Transfer Protein by an Allene Oxide Generated by 9-Lipoxygenase and Allene Oxide Synthase

Bakan

Hámberg

Perrocheau

et al. 2006

Journal of Biological Chemistry

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Lipid transfer proteins (LTPs) are ubiquitous plant lipidbinding proteins that have been associated with multiple developmental and stress responses. Although LTPs typically bind fatty acids and fatty acid derivatives in a non-covalent way, studies on the LTPs of barley seeds have identified an abundantly occurring covalently modified form, LTP1b, the lipid ligand of which has resisted clarification. In the present study, this adduct was identified as the ␣-ketol 9-hydroxy-10-oxo-12(Z)-octadecenoic acid. Further studies on the formation of LTP1b demonstrated that the ligand was introduced by nucleophilic attack of the free carboxylate group of the Asp-7 residue of the protein at carbon-9 of the allene oxide fatty acid 9(S),10-epoxy-10,12(Z)-octadecadienoic acid. This reactive oxylipin was produced in barley seeds by oxygenation of linoleic acid by 9-lipoxygenase followed by dehydration of the resulting hydroperoxide by allene oxide synthase. The generation of protein-oxylipin adducts represents a new function for plant allene oxide synthases, enzymes that have earlier been implicated mainly in the biosynthesis of the jasmonate family of plant hormones. Additionally, the LTP-allene oxide synthase interaction opens new perspectives regarding the roles of LTPs in the signaling of plant defense and development.

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“…The conversion of storage triacylglycerols by ␤-oxidation provides metabolic energy and carbon skeletons for germination and early post-germinative seedling growth in oil seed plants (5) and metabolic energy and carbon for the production of hydrolytic enzymes in cereals (6). It is a salvage pathway for fatty acids during foliar senescence (7), supplies respiratory substrates to carbohydrate-deprived tissue (8), and at a lower level, is a constitutive property of all plant tissues most likely involved with membrane lipid turnover (7).…”

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confidence: 99%

“…Acyl-CoA oxidase (ACX) 6 oxidizes acyl-CoA to 2-trans-enoyl-CoA using FAD as co-enzyme. A multifunctional protein (MFP) adds water over the 2-trans-enoyl-CoA double bond and oxidizes the resultant L-3-hydroxyacylCoA using NAD ϩ to 3-keto-acyl-CoA.…”

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confidence: 99%

The Multifunctional Protein in Peroxisomal β-Oxidation

Arent¹,

Christensen²,

Pye³

et al. 2010

Journal of Biological Chemistry

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Plant fatty acids can be completely degraded within the peroxisomes. Fatty acid degradation plays a role in several plant processes including plant hormone synthesis and seed germination. Two multifunctional peroxisomal isozymes, MFP2 and AIM1, both with 2-trans-enoyl-CoA hydratase and L-3-hydroxyacyl-CoA dehydrogenase activities, function in mouse ear cress (Arabidopsis thaliana) peroxisomal ␤-oxidation, where fatty acids are degraded by the sequential removal of two carbon units. A deficiency in either of the two isozymes gives rise to a different phenotype; the biochemical and molecular background for these differences is not known. Structure determination of Arabidopsis MFP2 revealed that plant peroxisomal MFPs can be grouped into two families, as defined by a specific pattern of amino acid residues in the flexible loop of the acylbinding pocket of the 2-trans-enoyl-CoA hydratase domain. This could explain the differences in substrate preferences and specific biological functions of the two isozymes. The in vitro substrate preference profiles illustrate that the Arabidopsis AIM1 hydratase has a preference for short chain acyl-CoAs compared with the Arabidopsis MFP2 hydratase. Remarkably, neither of the two was able to catabolize enoyl-CoA substrates longer than 14 carbon atoms efficiently, suggesting the existence of an uncharacterized long chain enoyl-CoA hydratase in Arabidopsis peroxisomes.Fatty acids are degraded by the sequential removal of two carbon units in a process known as ␤-oxidation (Fig. 1). This process is ubiquitous and takes its name from the oxidation taking place at the carbon atom ␤ to the carboxyl group. The discovery of a peroxisomal ␤-oxidation system was made in plants (1), and whereas peroxisomal ␤-oxidation in animals appears to be merely a fatty acid chain-shortening machine feeding mitochondrial ␤-oxidation, plant and fungal ␤-oxidation takes place almost entirely in the peroxisomes. The products of the reaction are H 2 O 2 , acetyl-CoA, reducing equivalents, and a variety of chain length-shortened acyl-containing molecules like the plant hormones jasmonic acid (2) and indole-3-acetic acid (3, 4).The conversion of storage triacylglycerols by ␤-oxidation provides metabolic energy and carbon skeletons for germination and early post-germinative seedling growth in oil seed plants (5) and metabolic energy and carbon for the production of hydrolytic enzymes in cereals (6). It is a salvage pathway for fatty acids during foliar senescence (7), supplies respiratory substrates to carbohydrate-deprived tissue (8), and at a lower level, is a constitutive property of all plant tissues most likely involved with membrane lipid turnover (7).Three proteins (each present as several isozymes) that host a total of four enzyme activities constitute the core of peroxisomal ␤-oxidation. Acyl-CoA oxidase (ACX) 6 oxidizes acyl-CoA to 2-trans-enoyl-CoA using FAD as co-enzyme. A multifunctional protein (MFP) adds water over the 2-trans-enoyl-CoA double bond and oxidizes the resultant L-3-hydroxyacylCoA usin...

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Programmed cell death in cereal aleurone

Cited by 63 publications

References 58 publications

Morphological classification of plant cell deaths

Morphological classification of plant cell deaths

Specific Adduction of Plant Lipid Transfer Protein by an Allene Oxide Generated by 9-Lipoxygenase and Allene Oxide Synthase

The Multifunctional Protein in Peroxisomal β-Oxidation

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