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Sieńko K, Poormassalehgoo A, Yamada K, Goto-Yamada S. Microautophagy in Plants: Consideration of Its Molecular Mechanism. Cells 2020; 9:cells9040887. [PMID: 32260410 PMCID: PMC7226842 DOI: 10.3390/cells9040887] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 02/06/2023] Open
Abstract
Microautophagy is a type of autophagy. It is characterized by direct enclosing with the vacuolar/lysosomal membrane, which completes the isolation and uptake of cell components in the vacuole. Several publications present evidence that plants exhibit microautophagy. Plant microautophagy is involved in anthocyanin accumulation in the vacuole, eliminating damaged chloroplasts and degrading cellular components during starvation. However, information on the molecular mechanism of microautophagy is less available than that on the general macroautophagy, because the research focusing on microautophagy has not been widely reported. In yeast and animals, it is suggested that microautophagy can be classified into several types depending on morphology and the requirements of autophagy-related (ATG) genes. This review summarizes the studies on plant microautophagy and discusses possible techniques for a future study in this field while taking into account the information on microautophagy obtained from yeast and animals.
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Zhou S, Hong Q, Li Y, Li Q, Li R, Zhang H, Wang M, Yuan X. Macroautophagy occurs in distal TMV-uninfected root tip tissue of tomato taking place systemic PCD. PROTOPLASMA 2018; 255:3-9. [PMID: 28551700 DOI: 10.1007/s00709-017-1125-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 05/12/2017] [Indexed: 06/07/2023]
Abstract
Autophagy is an important mechanism for recycling cell materials upon encountering stress conditions. Our previous studies had shown that TMV infection could lead to systemic PCD in the distal uninfected tissues, including root tip and shoot tip tissues. But it is not clear whether there is autophagy in the distal apical meristem of TMV-induced plants. To better understand the autophagy process during systemic PCD, here we investigated the formation and type of autophagy in the root meristem cells occurring PCD. Transmission electron microscopy assay revealed that the autophagic structures formed by the fusion of vesicles, containing the sequestered cytoplasm, multilamellar bodies, and degraded mitochondria. In the PCD progress, many mitochondria appeared degradation with blurred inner membrane structure. And the endoplasmic reticulum was broke into small fragments. Finally, the damaged mitochodria were engulfed and degraded by the autophagosomes. These results indicated that during the systemic PCD process of root tip cells, the classical macroautophagy occurred, and the cell contents and damaged organelles (mitochondria) would be self-digested by autophagy.
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Affiliation(s)
- Shumin Zhou
- Lab of Plant Development Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai, China
| | - Qiang Hong
- Lab of Plant Development Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai, China
| | - Yang Li
- Lab of Plant Development Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai, China
- School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Qi Li
- School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Ruisha Li
- Lab of Plant Development Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai, China
- School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Hongli Zhang
- Lab of Plant Development Biology, Shanghai Key Laboratory of Bio-Energy Crops, School of Life Sciences, Shanghai University, Shanghai, China
- School of Life Sciences, Shanghai University, Shanghai, 200444, China
| | - Mao Wang
- College of Biology, China Agriculture University, Beijing, 100094, China.
| | - Xiaojun Yuan
- School of Life Sciences, Shanghai University, Shanghai, 200444, China.
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Shibuya K, Yamada T, Ichimura K. Morphological changes in senescing petal cells and the regulatory mechanism of petal senescence. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:5909-5918. [PMID: 27625416 DOI: 10.1093/jxb/erw337] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Petal senescence, or programmed cell death (PCD) in petals, is a developmentally regulated and genetically programmed process. During petal senescence, petal cells show morphological changes associated with PCD: tonoplast rupture and rapid destruction of the cytoplasm. This type of PCD is classified as vacuolar cell death or autolytic PCD based on morphological criteria. In PCD of petal cells, characteristic morphological features including an autophagy-like process, chromatin condensation, and nuclear fragmentation are also observed. While the phytohormone ethylene is known to play a crucial role in petal senescence in some plant species, little is known about the early regulation of ethylene-independent petal senescence. Recently, a NAC (NAM/ATAF1,2/CUC2) transcription factor was reported to control the progression of PCD during petal senescence in Japanese morning glory, which shows ethylene-independent petal senescence. In ethylene-dependent petal senescence, functional analyses of transcription factor genes have revealed the involvement of a basic helix-loop-helix protein and a homeodomain-leucine zipper protein in the transcriptional regulation of the ethylene biosynthesis pathway. Here we review the recent advances in our knowledge of petal senescence, mostly focusing on the morphology of senescing petal cells and the regulatory mechanisms of PCD by senescence-associated transcription factors during petal senescence.
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Affiliation(s)
- Kenichi Shibuya
- Institute of Vegetable and Floriculture Science, NARO, Tsukuba 305-0852, Japan
| | - Tetsuya Yamada
- Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | - Kazuo Ichimura
- Institute of Vegetable and Floriculture Science, NARO, Tsukuba 305-0852, Japan
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Kamdee C, Kirasak K, Ketsa S, van Doorn WG. Vesicles between plasma membrane and cell wall prior to visible senescence of Iris and Dendrobium flowers. JOURNAL OF PLANT PHYSIOLOGY 2015; 188:37-43. [PMID: 26454639 DOI: 10.1016/j.jplph.2015.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 02/02/2015] [Accepted: 02/25/2015] [Indexed: 05/28/2023]
Abstract
Cut Iris flowers (Iris x hollandica, cv. Blue Magic) show visible senescence about two days after full opening. Epidermal cells of the outer tepals collapse due to programmed cell death (PCD). Transmission electron microscopy (TEM) showed irregular swelling of the cell walls, starting prior to cell collapse. Compared to cells in flowers that had just opened, wall thickness increased up to tenfold prior to cell death. Fibrils were visible in the swollen walls. After cell death very little of the cell wall remained. Prior to and during visible wall swelling, vesicles (paramural bodies) were observed between the plasma membrane and the cell walls. The vesicles were also found in groups and were accompanied by amorphous substance. They usually showed a single membrane, and had a variety of diameters and electron densities. Cut Dendrobium hybrid cv. Lucky Duan flowers exhibited visible senescence about 14 days after full flower opening. Paramural bodies were also found in Dendrobium tepal epidermis and mesophyll cells, related to wall swelling and degradation. Although alternative explanations are well possible, it is hypothesized that paramural bodies carry enzymes involved in cell wall breakdown. The literature has not yet reported such bodies in association with senescence/PCD.
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Affiliation(s)
- Channatika Kamdee
- Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
| | - Kanjana Kirasak
- Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand
| | - Saichol Ketsa
- Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok 10900, Thailand; Academy of Science, The Royal Society, Dusit, Bangkok 10300, Thailand.
| | - Wouter G van Doorn
- Mann Laboratory, Department of Plant Sciences, University of California, Davis, CA 95616, USA
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van Doorn WG, Kirasak K, Ketsa S. Macroautophagy and microautophagy in relation to vacuole formation in mesophyll cells of Dendrobium tepals. JOURNAL OF PLANT PHYSIOLOGY 2015; 177:67-73. [PMID: 25666541 DOI: 10.1016/j.jplph.2015.01.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/09/2015] [Accepted: 01/09/2015] [Indexed: 05/04/2023]
Abstract
Prior to flower opening, mesophyll cells at the vascular bundles of Dendrobium tepals showed a large increase in vacuolar volume, partially at the expense of the cytoplasm. Electron micrographs indicated that this increase in vacuolar volume was mainly due to vacuole fusion. Macroautophagous structures typical of plant cells were observed. Only a small part of the decrease in cytoplasmic volume seemed due to macroautophagy. The vacuoles contained vesicles of various types, including multilamellar bodies. It was not clear if these vacuolar inclusions were due to macroautophagy or microautophagy. Only a single structure was observed of a protruding vacuole, indicating microautophagy. It is concluded that macroautophagy occurs in these cells but its role in vacuole formation seems small, while a possible role of microautophagy in vacuole formation might be hypothesized. Careful labeling of organelle membranes seems required to advance our insight in plant macro- and microautophagy and their roles in vacuole formation.
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Affiliation(s)
- Wouter G van Doorn
- Mann Laboratory, Department of Plant Sciences, University of California, Davis, CA 95616, USA.
| | - Kanjana Kirasak
- Khon Kaen Field Crops Research Center, Amphur Muang, Khon Kaen 40000, Thailand
| | - Saichol Ketsa
- Department of Horticulture, Faculty of Agriculture, Kasetsart University, Bangkok Campus, Bangkok 10900, Thailand; Academy of Science, The Royal Institute, Dusit, Bangkok 10300, Thailand.
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