Old Enzymes for a New Job (Herbicide Detoxification in Plants)

Kreuz, Klaus; Tommasini, Roberto; Martinoia, Enrico

doi:10.1104/pp.111.2.349

Cited by 278 publications

(208 citation statements)

References 22 publications

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“…The product of this reaction is red chlorophyll catabolite, which, without release from PAO, is site-specifically reduced by red chlorophyll catabolite reductase to yield the primary fluorescent chlorophyll catabolite (FCC), pFCC Rodoni et al, 1997). After export from the chloroplast (Matile et al, 1992), pFCC is modified by reactions reminiscent of detoxification processes widely occurring in plants (Kreuz et al, 1996). Thus, pFCC is hydroxylated and after further (species-specific) modification (Krä utler, 2003;Hö rtensteiner, 2006), the resulting FCCs are imported into the vacuole by a primary active transport process (Hinder et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

et al. 2009

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During leaf senescence, chlorophyll is removed from thylakoid membranes and converted in a multistep pathway to colorless breakdown products that are stored in vacuoles. Dephytylation, an early step of this pathway, increases water solubility of the breakdown products. It is widely accepted that chlorophyll is converted into pheophorbide via chlorophyllide. However, chlorophyllase, which converts chlorophyll to chlorophyllide, was found not to be essential for dephytylation in Arabidopsis thaliana. Here, we identify pheophytinase (PPH), a chloroplast-located and senescence-induced hydrolase widely distributed in algae and land plants. In vitro, Arabidopsis PPH specifically dephytylates the Mg-free chlorophyll pigment, pheophytin (phein), yielding pheophorbide. An Arabidopsis mutant deficient in PPH (pph-1) is unable to degrade chlorophyll during senescence and therefore exhibits a stay-green phenotype. Furthermore, pph-1 accumulates phein during senescence. Therefore, PPH is an important component of the chlorophyll breakdown machinery of senescent leaves, and we propose that the sequence of early chlorophyll catabolic reactions be revised. Removal of Mg most likely precedes dephytylation, resulting in the following order of early breakdown intermediates: chlorophyll / pheophytin / pheophorbide. Chlorophyllide, the last precursor of chlorophyll biosynthesis, is most likely not an intermediate of breakdown. Thus, chlorophyll anabolic and catabolic reactions are metabolically separated.

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Section: Introductionmentioning

confidence: 99%

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

et al. 2009

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“…In phase III, the conjugates are either secreted and deposited in the cell wall, or transported to the vacuole by plasmalemma and tonoplast-localized ATP-binding cassette (ABC) transporters, respectively. Finally, xenobiotic-glutathione conjugates may be further processed, partially degraded or subject to secondary conjugations in phase IV (Kreuz, Tommasini & Martinoia 1996;Davies & Caseley 1999;Yuan et al 2007;Riechers et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Safeners recruit multiple signalling pathways for the orchestrated induction of the cellular xenobiotic detoxification machinery in Arabidopsis

Behringer

Bartsch

Schaller

2011

Plant Cell & Environment

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Safeners enhance herbicide tolerance in crop plants but not in target weeds, thus improving herbicide selectivity. The safeners isoxadifen-ethyl and mefenpyr-diethyl protect cereal crops from sulfonyl urea herbicides in postemergence application. The two safeners were shown here to induce the cellular xenobiotic detoxification machinery in Arabidopsis thaliana when applied to leaves in a way mimicking field application. Gene expression profiling revealed the induction of 446 genes potentially involved in the detoxification process. Transgenic Arabidopsis plants expressing a reporter gene under control of a safenerresponsive maize promoter were used as a model system to study the safener signalling pathway. Reporter gene analysis in the tga2/3/5/6, sid2-2 and npr1 mutants as compared with the wild-type background showed that safener inducibility required TGA transcription factors and salicylic acid (SA) in a NON-EXPRESSOR of PR-1 (NPR1)-independent pathway converging on two as-1 promoter elements. For the majority of the safener-responsive Arabidopsis genes, a similar dependence on TGA transcription factors and/or SA was shown by gene expression profiling in wild-type plants as compared with the tga2/3/5/6 and sid2-2 mutants. Thirty-eight percent of the genes, however, were induced by safeners in a TGA/SA-independent manner. These genes are likely to be controlled by WRKY transcription factors and cognate W-boxes in their promoters.

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“…This yields a primary fluorescent catabolite (pFCC), which is exported from the plastid by a primary active transporter. Further steps in the pathway are reminiscent of detoxification processes widely occurring in plants (Kreuz et al, 1996). Thus, pFCCs are activated by hydroxylation and after further modification they are imported into the vacuole by another primary active transport system.…”

Section: Introductionmentioning

confidence: 99%

Stay-green protein, defective in Mendel’s green cotyledon mutant, acts independent and upstream of pheophorbide a oxygenase in the chlorophyll catabolic pathway

2008

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Old Enzymes for a New Job (Herbicide Detoxification in Plants)

Cited by 278 publications

References 22 publications

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

Pheophytin Pheophorbide Hydrolase (Pheophytinase) Is Involved in Chlorophyll Breakdown during Leaf Senescence in Arabidopsis

Safeners recruit multiple signalling pathways for the orchestrated induction of the cellular xenobiotic detoxification machinery in Arabidopsis

Stay-green protein, defective in Mendel’s green cotyledon mutant, acts independent and upstream of pheophorbide a oxygenase in the chlorophyll catabolic pathway

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