NON-YELLOWING2 (NYE2), a Close Paralog of NYE1, Plays a Positive Role in Chlorophyll Degradation in Arabidopsis

Wu, Shouxin; Li, Zhongpeng; Yang, Lifeng; Xie, Zuokun; Chen, Junyi; Zhang, Wei; Liu, Tianqi; Gao, Shan; Gao, Jiong; Zhu, Yihua; Xin, Jiwen; Ren, Guodong; Benke, Kálmán

doi:10.1016/j.molp.2015.12.016

Cited by 49 publications

(52 citation statements)

References 12 publications

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“…There are three SGR genes in the Arabidopsis genome: SGR1 , SGR2 and SGRL (Sakuraba et al ., ; Shimoda et al ., ). SGR1 and SGR2 are expressed during senescence, and the sgr1 / sgr2 double mutant shows a strong stay‐green phenotype (Wu et al ., ). These results indicate that SGR1 and SGR2 are responsible for Chl degradation during senescence.…”

Section: Discussionmentioning

confidence: 97%

Mg‐dechelatase is involved in the formation of photosystem II but not in chlorophyll degradation in Chlamydomonas reinhardtii

et al. 2019

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Summary The STAY‐GREEN (SGR) gene encodes Mg‐dechelatase which catalyzes the conversion of chlorophyll (Chl) a to pheophytin (Pheo) a. This reaction is the first and most important regulatory step in the Chl degradation pathway. Conversely, Pheo a is an indispensable molecule in photosystem (PS) II, suggesting the involvement of SGR in the formation of PSII. To investigate the physiological functions of SGR, we isolated Chlamydomonas sgr mutants by screening an insertion‐mutant library. The sgr mutants had reduced maximum quantum efficiency of PSII (Fv/Fm) and reduced Pheo a levels. These phenotypes were complemented by the introduction of the Chlamydomonas SGR gene. Blue Native polyacrylamide gel electrophoresis and immunoblotting analysis showed that although PSII levels were reduced in the sgr mutants, PSI and light‐harvesting Chl a/b complex levels were unaffected. Under nitrogen starvation conditions, Chl degradation proceeded in the sgr mutants as in the wild type, indicating that ChlamydomonasSGR is not required for Chl degradation and primarily contributes to the formation of PSII. In contrast, in the Arabidopsis sgr triple mutant (sgr1 sgr2 sgrL), which completely lacks SGR activity, PSII was synthesized normally. These results suggest that the Arabidopsis SGR participates in Chl degradation while the ChlamydomonasSGR participates in PSII formation despite having the same catalytic property.

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Section: Discussionmentioning

confidence: 97%

Mg‐dechelatase is involved in the formation of photosystem II but not in chlorophyll degradation in Chlamydomonas reinhardtii

et al. 2019

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“…Because of its physical interaction with Chl catabolic enzymes at light-harvesting complex II, NYE1 was proposed as a recruiter of Chl catabolic enzymes in senescing chloroplasts to promote efficient Chl degradation (Sakuraba et al, 2012). In addition, NYE2/SGR2, a stand-by paralog of NYE1, also was identified as a positive regulator of Chl degradation (Wu et al, 2016). Remarkably, Shimoda et al (2016) recently showed that NYE1 acts as a magnesium dechelatase during senescence in Arabidopsis.…”

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confidence: 99%

Suppressor of Overexpression of CO 1 Negatively Regulates Dark-Induced Leaf Degreening and Senescence by Directly Repressing Pheophytinase and Other Senescence-Associated Genes in Arabidopsis

et al. 2017

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Although the biochemical pathway of chlorophyll (Chl) degradation has been largely elucidated, how Chl is rapidly yet coordinately degraded during leaf senescence remains elusive. Pheophytinase (PPH) is the enzyme for catalyzing the removal of the phytol group from pheophytin , and expression is significantly induced during leaf senescence. To elucidate the transcriptional regulation of , we used a yeast () one-hybrid system to screen for its trans-regulators. SUPPRESSOR OF OVEREXPRESSION OF CO 1 (SOC1), a key flowering pathway integrator, was initially identified as one of the putative trans-regulators of After dark treatment, leaves of an knockdown mutant () showed an accelerated yellowing phenotype, whereas those of -overexpressing lines exhibited a partial stay-green phenotype. and expression showed a negative correlation during leaf senescence. Substantially, SOC1 protein could bind specifically to the CArG box of the promoter in vitro and in vivo, and overexpression of significantly inhibited the transcriptional activity of the promoter in Arabidopsis () protoplasts. Importantly, (a knockout mutant) double mutant displayed a stay-green phenotype similar to that of during dark treatment. These results demonstrated that SOC1 inhibits Chl degradation via negatively regulating expression. In addition, measurement of the Chl content and the maximum photochemical efficiency of photosystem II of and leaves after dark treatment suggested that SOC1 also negatively regulates the general senescence process. Seven () were thereafter identified as its potential target genes, and and were experimentally confirmed. Together, we reveal that SOC1 represses dark-induced leaf Chl degradation and senescence in general in Arabidopsis.

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“…In Arabidopsis, three SGR genes are present, i.e. SGR1, SGR2 and SGR-like (SGRL) (Hörtensteiner 2009;Sakuraba et al 2014;Wu et al 2016). Dephytylation, i.e.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the pheophorbide a oxygenase/phyllobilin pathway of chlorophyll breakdown in grasses

Das

Christ

Hörtensteiner

2018

Planta

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Although the PAO/phyllobilin pathway of chlorophyll breakdown is active in grass leaf senescence, the abundance of phyllobilins is far below the amount of degraded chlorophyll. The yellowing of fully developed leaves is the most prominent visual symptom of plant senescence. Thereby, chlorophyll is degraded via the so-called pheophorbide a oxygenase (PAO)/phyllobilin pathway to a species-specific set of phyllobilins, linear tetrapyrrolic products of chlorophyll breakdown. Here, we investigated the diversity and abundance of phyllobilins in cereal and forage crops, i.e. barley, rice, ryegrass, sorghum and wheat, using liquid chromatography-mass spectrometry. A total of thirteen phyllobilins were identified, among them four novel, not yet described ones, pointing to a rather high diversity of phyllobilin-modifying activities present in the Gramineae. Along with these phyllobilins, barley orthologs of known Arabidopsis thaliana chlorophyll catabolic enzymes were demonstrated to localize in the chloroplast, and two of them, i.e. PAO and pheophytin pheophorbide hydrolase, complemented respective Arabidopsis mutants. These data confirm functionality of the PAO/phyllobilin pathway in grasses. Interestingly, when comparing phyllobilin abundance with amounts of degraded chlorophyll in senescent leaves, in most analyzed grass species only minor fractions of chlorophyll were recovered as phyllobilins, opposite to A. thaliana where phyllobilin quantities match degraded chlorophyll rather well. These data show that, despite the presence and activity of the PAO/phyllobilin pathway in barley (and other cereals), phyllobilins do not accumulate stoichiometrically, implying possible degradation of chlorophyll beyond the phyllobilin level.

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NON-YELLOWING2 (NYE2), a Close Paralog of NYE1, Plays a Positive Role in Chlorophyll Degradation in Arabidopsis

Cited by 49 publications

References 12 publications

Mg‐dechelatase is involved in the formation of photosystem II but not in chlorophyll degradation in Chlamydomonas reinhardtii

Mg‐dechelatase is involved in the formation of photosystem II but not in chlorophyll degradation in Chlamydomonas reinhardtii

Suppressor of Overexpression of CO 1 Negatively Regulates Dark-Induced Leaf Degreening and Senescence by Directly Repressing Pheophytinase and Other Senescence-Associated Genes in Arabidopsis

Characterization of the pheophorbide a oxygenase/phyllobilin pathway of chlorophyll breakdown in grasses

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