scholarly journals Overexpressing 7-Hydroxymethyl Chlorophyll a Reductase Alleviates Non-Programmed Cell Death during Dark-Induced Senescence in Intact Arabidopsis Plants

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1143
Author(s):  
Xueyun Hu ◽  
Chu Zeng ◽  
Jinling Su ◽  
Imran Khan ◽  
Ahmad Zada ◽  
...  
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Leaf Senescence ◽  
Pheophorbide A ◽  
Chl A ◽  
Metabolic Intermediates ◽  
Complex Process ◽  
Detached Leaves ◽  
Last Stage ◽  
Whole Plants

Leaf senescence, the last stage of leaf development, is a well-regulated and complex process for investigation. For simplification, dark-induced leaf senescence has frequently been used to mimic the natural senescence of leaves because many typical senescence symptoms, such as chlorophyll (Chl) and protein degradation, also occur under darkness. In this study, we compared the phenotypes of leaf senescence that occurred when detached leaves or intact plants were incubated in darkness to induce senescence. We found that the symptoms of non-programmed cell death (non-PCD) with remaining green coloration occurred more heavily in the senescent leaves of whole plants than in the detached leaves. The pheophorbide a (Pheide a) content was also shown to be much higher in senescent leaves when whole plants were incubated in darkness by analyses of leaf Chl and its metabolic intermediates. In addition, more serious non-PCD occurred and more Pheide a accumulated in senescent leaves during dark incubation if the soil used for plant growth contained more water. Under similar conditions, the non-PCD phenotype was alleviated and the accumulation of Pheide a was reduced by overexpressing 7-hydroxymethyl Chl a (HMChl a) reductase (HCAR). Taken together, we conclude that a high soil water content induced non-PCD by decreasing HCAR activity when whole plants were incubated in darkness to induce senescence; thus, the investigation of the fundamental aspects of biochemistry and the regulation of leaf senescence are affected by using dark-induced leaf senescence.

Programmed cell death during rice leaf senescence is nonapoptotic

2002 ◽  
Vol 155 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Ruey-Hua Lee ◽  
Shu-Chen Grace Chen
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Leaf Senescence ◽  
Rice Leaf

scholarly journals Programmed cell death in diazotrophs and the fate of organic matter in the western tropical South Pacific Ocean during the OUTPACE cruise

2018 ◽  
Vol 15 (12) ◽  
pp. 3893-3908 ◽  
Author(s):  
Dina Spungin ◽  
Natalia Belkin ◽  
Rachel A. Foster ◽  
Marcus Stenegren ◽  
Andrea Caputo ◽  
...  
Keyword(s):  
Cell Death ◽  
Organic Matter ◽  
Pacific Ocean ◽  
Programmed Cell Death ◽  
South Pacific ◽  
Sediment Traps ◽  
Vertical Flux ◽  
Filamentous Cyanobacterium ◽  
Chl A ◽  
South Pacific Ocean

Abstract. The fate of diazotroph (N2 fixers) derived carbon (C) and nitrogen (N) and their contribution to vertical export of C and N in the western tropical South Pacific Ocean was studied during OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment). Our specific objective during OUTPACE was to determine whether autocatalytic programmed cell death (PCD), occurring in some diazotrophs, is an important mechanism affecting diazotroph mortality and a factor regulating the vertical flux of organic matter and, thus, the fate of the blooms. We sampled at three long duration (LD) stations of 5 days each (LDA, LDB and LDC) where drifting sediment traps were deployed at 150, 325 and 500 m depth. LDA and LDB were characterized by high chlorophyll a (Chl a) concentrations (0.2–0.6 µg L−1) and dominated by dense biomass of the filamentous cyanobacterium Trichodesmium as well as UCYN-B and diatom–diazotroph associations (Rhizosolenia with Richelia-detected by microscopy and het-1 nifH copies). Station LDC was located at an ultra-oligotrophic area of the South Pacific gyre with extremely low Chl a concentration (∼ 0.02 µg L−1) with limited biomass of diazotrophs predominantly the unicellular UCYN-B. Our measurements of biomass from LDA and LDB yielded high activities of caspase-like and metacaspase proteases that are indicative of PCD in Trichodesmium and other phytoplankton. Metacaspase activity, reported here for the first time from oceanic populations, was highest at the surface of both LDA and LDB, where we also obtained high concentrations of transparent exopolymeric particles (TEP). TEP were negatively correlated with dissolved inorganic phosphorus and positively coupled to both the dissolved and particulate organic carbon pools. Our results reflect the increase in TEP production under nutrient stress and its role as a source of sticky carbon facilitating aggregation and rapid vertical sinking. Evidence for bloom decline was observed at both LDA and LDB. However, the physiological status and rates of decline of the blooms differed between the stations, influencing the amount of accumulated diazotrophic organic matter and mass flux observed in the traps during our experimental time frame. At LDA sediment traps contained the greatest export of particulate matter and significant numbers of both intact and decaying Trichodesmium, UCYN-B and het-1 compared to LDB where the bloom decline began only 2 days prior to leaving the station and to LDC where no evidence for bloom or bloom decline was seen. Substantiating previous findings from laboratory cultures linking PCD to carbon export in Trichodesmium, our results from OUTPACE indicate that nutrient limitation may induce PCD in high biomass blooms such as displayed by Trichodesmium or diatom–diazotroph associations. Furthermore, PCD combined with high TEP production will tend to facilitate cellular aggregation and bloom termination and will expedite vertical flux to depth.

scholarly journals HCAR Is a Limitation Factor for Chlorophyll Cycle and Chlorophyll b Degradation in Chlorophyll-b-Overproducing Plants

Biomolecules ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1639
Author(s):  
Xuan Zhao ◽  
Ting Jia ◽  
Xueyun Hu
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Metabolic Pathway ◽  
Pivotal Role ◽  
Limiting Factor ◽  
Chlorophyll B ◽  
Green Color ◽  
Chl A ◽  
Cycle Regulation

The chlorophyll (Chl) cycle is the metabolic pathway for Chl a and Chl b inter-conversion. In this pathway, Chl b is synthesized from Chl a by the catalyzing action of chlorophyllide a oxygenase (CAO). In contrast, Chl b is firstly reduced to produce 7-hydroxymethyl Chl (HMChl) a, which is catalyzed by two isozymes of Chl b reductase (CBR), non-yellow coloring 1 (NYC1) and NYC1-like (NOL). Subsequently, HMChl a is reduced to Chl a by HMChl a reductase (HCAR). CAO plays a pivotal role in Chl a/b ratio regulation and plants over-accumulate Chl b in CAO-overexpressing plants. NYC1 is more accumulated in Chl-b-overproducing plants, while HCAR is not changed. To investigate the role of HCAR in Chl cycle regulation, the Chl metabolites of Chl-b-overproducing plants were analyzed. The results showed that HMChl a accumulated in these plants, and it decreased and the Chl a/b ratio increased by overexpressing HCAR, implying HCAR is insufficient for Chl cycle in Chl-b-overproducing plants. Furthermore, during dark-induced senescence, the non-programmed cell death symptoms (leaves dehydrated with green color retained) of Chl-b-overproducing plants were obviously alleviated, and the content of HM pheophorbide (HMPheide) a and Pheide b were sharply decreased by overexpressing HCAR. These results imply that HCAR is also insufficient for Chl degradation in Chl-b-overproducing plants during senescence, thus causing the accumulation of Chl metabolites and non-programmed cell death of leaves. With these results taken together, we conclude that HCAR is not well regulated and it is a limiting factor for Chl cycle and Chl b degradation in Chl-b-overproducing plants.

scholarly journals Necrosis-induced apoptosis promotes regeneration in Drosophila wing imaginal discs

Genetics ◽  
2021 ◽  
Author(s):  
Jacob Klemm ◽  
Michael J Stinchfield ◽  
Robin E Harris
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Tissue Loss ◽  
Similar Response ◽  
Wound Edge ◽  
Jnk Signaling ◽  
Drosophila Wing ◽  
Complex Process ◽  
Induced Apoptosis ◽  
Dying Cells

Abstract Regeneration is a complex process that requires a coordinated genetic response to tissue loss. Signals from dying cells are crucial to this process and are best understood in the context of regeneration following programmed cell death, like apoptosis. Conversely, regeneration following unregulated forms of death such as necrosis have yet to be fully explored. Here we have developed a method to investigate regeneration following necrosis using the Drosophila wing imaginal disc. We show that necrosis stimulates regeneration at an equivalent level to that of apoptosis-mediated cell death and activates a similar response at the wound edge involving localized JNK signaling. Unexpectedly however, necrosis also results in significant apoptosis far from the site of ablation, which we have termed necrosis-induced apoptosis (NiA). This apoptosis occurs independent of changes at the wound edge and importantly does not rely on JNK signaling. Furthermore, we find that blocking NiA limits proliferation and subsequently inhibits regeneration, suggesting that tissues damaged by necrosis can activate programmed cell death at a distance from the injury to promote regeneration.

Calcium inhibition halts developmental programmed cell death in the lace plant, Aponogeton madagascariensis?

Botany ◽  
2010 ◽  
Vol 88 (2) ◽  
pp. 206-210 ◽  
Author(s):  
Anna Elliott ◽  
Arunika H.L.A.N. Gunawardena
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Leaf Growth ◽  
Indirect Evidence ◽  
Ruthenium Red ◽  
Leaf Length ◽  
Leaf Morphogenesis ◽  
Whole Plants

This study examined the effect of the calcium channel blocker ruthenium red (RR) on developmental programmed cell death (PCD) and perforation formation in leaves of the aquatic lace plant ( Aponogeton madagascariensis (Mirbel) H. Bruggen). Plant immersion experiments were conducted using various concentrations (0, 10, 20, 30, and 40 µmol·L–1) of RR applied to whole plants over a 3 to 4 week period. The ratio of number of leaf perforations per centimetre of leaf length along with leaf length were used to assess treatment effect. While the ratio of number of perforations per centimetre of leaf length was significantly reduced with RR treatment, leaf length was not, overall, significantly affected by RR. Therefore, it was concluded that RR was able to inhibit calcium movement and halt PCD, thus reducing perforation formation without having detrimental effects on leaf growth. The present research provides indirect evidence of the possible role of calcium in developmental PCD in vivo during leaf morphogenesis in the lace plant. Furthermore, it suggests the usefulness of the lace plant as a model system for pharmacological studies involving developmental PCD.

Plant oxylipins: role of jasmonic acid during programmed cell death, defence and leaf senescence

FEBS Journal ◽  
2009 ◽  
Vol 276 (17) ◽  
pp. 4666-4681 ◽  
Author(s):  
Christiane Reinbothe ◽  
Armin Springer ◽  
Iga Samol ◽  
Steffen Reinbothe
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Jasmonic Acid ◽  
Leaf Senescence

Aspects of programmed cell death during leaf senescence of mono- and dicotyledonous plants

PROTOPLASMA ◽  
2000 ◽  
Vol 214 (1-2) ◽  
pp. 93-101 ◽  
Author(s):  
E. Simeonova ◽  
A. Sikora ◽  
M. Charzyńska ◽  
A. Mostowska
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Leaf Senescence ◽  
Dicotyledonous Plants

scholarly journals Hsp70 plays a role in programmed cell death during the remodelling of leaves of the lace plant (Aponogeton madagascariensis)

2019 ◽  
Author(s):  
Nathan M Rowarth ◽  
Adrian N Dauphinee ◽  
Georgia L Denbigh ◽  
Arunika Hlan Gunawardena
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Leaf Development ◽  
Anthocyanin Content ◽  
Plant Leaves ◽  
Antioxidant Treatment ◽  
Plant Leaf ◽  
Whole Plants ◽  
Shock Proteins

Abstract Lace plant leaves utilize programmed cell death (PCD) to form perforations during development. The role of heat shock proteins (Hsps) in PCD during lace plant leaf development is currently unknown. Hsp70 amounts were measured throughout lace plant leaf development, and the results indicate that it is highest before and during PCD. Increased Hsp70 amounts correlate with raised anthocyanin content and caspase-like protease (CLP) activity. To investigate the effects of Hsp70 on leaf development, whole plants were treated with either of the known regulators of PCD [reactive oxygen species (ROS) or antioxidants] or an Hsp70 inhibitor, chlorophenylethynylsulfonamide (PES-Cl). ROS treatment significantly increased Hsp70 2-fold and CLP activity in early developing leaves, but no change in anthocyanin and the number of perforations formed was observed. Antioxidant treatment significantly decreased Hsp70, anthocyanin, and CLP activity in early leaves, resulting in the fewest perforations. PES-Cl (25 μM) treatment significantly increased Hsp70 4-fold in early leaves, while anthocyanin, superoxide, and CLP activity significantly declined, leading to fewer perforations. Results show that significantly increased (4-fold) or decreased Hsp70 amounts lead to lower anthocyanin and CLP activity, inhibiting PCD induction. Our data support the hypothesis that Hsp70 plays a role in regulating PCD at a threshold in lace plant leaf development. Hsp70 affects anthocyanin content and caspase-like protease activity, and helps regulate PCD during the remodelling of leaves of lace plant, Aponogeton madagascariensis.

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