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Nogueira FM, Nogueira PVF, Vanzela ALL, Rocha DM. Ultrastructural analysis of Rhynchospora ovules: The first record of Cyperaceae megagametophyte on transmission electron microscope. Micron 2020; 140:102962. [PMID: 33099208 DOI: 10.1016/j.micron.2020.102962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 10/05/2020] [Accepted: 10/06/2020] [Indexed: 11/28/2022]
Abstract
Microsporogenesis and microgametogenesis are unusual in sedges (Cyperaceae), the third largest monocotyledonous family, as three microspores are aborted in favor of a single functional microspore. However, studies using light microscopy show that megasporogenesis and megagametogenesis occur normally. Nevertheless, the lack of ultrastructural details limits our knowledge of female gametophyte development in this family. Given the importance of morphological studies of reproductive structures, ovules and megagametophytes of Rhynchospora pubera were analyzed under transmission electron microscopy for the first time. Overall, ovules presented features similar to those described for the family, but ultrastructural details revealed an absence of a clear boundary between the egg cell and the central cell cytoplasm. Most interestingly, antipodal and nucellar cells showed several signs of vacuolar cell death, which suggest that programmed autolysis in sporogenous and gametophytic tissue is common in gametophyte development in the Cyperaceae. This may be related to the reproductive success of this family.
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Affiliation(s)
- Fernanda M Nogueira
- Laboratory of Algae and Plants of Amazonia (LAPAM), Federal University of Oeste do Pará (UFOPA) Campus Oriximiná, Rodovia PA-254, 257, Oriximiná, PA, Brazil.
| | - Paulo Vinicius F Nogueira
- Laboratory of Electron Microscopy and Microanalysis (LMEM), State University of Londrina (UEL), 86057-970, PR, Brazil
| | - André Luís Laforga Vanzela
- Laboratory of Cytogenetics and Plant Diversity (LCDV), State University of Londrina (UEL), 86057-970, PR, Brazil
| | - Danilo Massuia Rocha
- Department of Structural Biology, Molecular and Genetics (DEBIOGEM), State University of Ponta Grossa (UEPG), Carlos Cavalcanti Avenue 4748, 84030-900, PR, Brazil; Laboratory of Cytogenetics and Plant Diversity (LCDV), State University of Londrina (UEL), 86057-970, PR, Brazil.
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Haddad IVN, de Sá-Haiad B, de Santiago-Fernandes LDR, Machado SR. Megagametophyte development and female sterility in Maytenus obtusifolia Mart. (Celastraceae). Protoplasma 2019; 256:1667-1680. [PMID: 31286267 DOI: 10.1007/s00709-019-01413-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/03/2019] [Indexed: 06/09/2023]
Abstract
Reproduction in flowering plants is closely related to the megagametophyte, since the megagametophyte is involved in pollen tube reception and contains the two female gametes-egg cell and central cell. Previous conventional light microscopy methods have shown that female sterility in perfect flowers of Maytenus obtusifolia is associated with the occurrence of sterile ovules whose megagametophytes have hypertrophied synergids. Here, using transmission electron microscopy and cytochemical methods, we compare the megagametophytes in fertile and sterile ovules from perfect and pistillate flowers, and investigate the cellular events that result in the degradation of the megagametophyte cells from sterile ovules. In fertile ovules of perfect and pistillate flowers, mature megagametophytes have two synergids, egg cell and central cell. In fertile ovules, the synergids present an extensive rough endoplasmic reticulum (RER) profile, large populations of mitochondria, when compared to egg cells, vesicles, Golgi bodies, plastids and a nucleus with heterochromatin. Besides that, the egg cell has a small population of organelles and the central cell exhibits cytoplasm with free ribosomes, RER, vesicles originating from the RER, Golgi bodies and oil inclusions. In mature megagametophytes from sterile ovules of perfect and pistillate flowers, massive autophagy occurs by tonoplast rupture promoting hydrolase release, leading to protoplast and cell wall degradation-typical evidence of programmed cell death (PCD). Therefore, female sterility in the majority of M. obtusifolia sterile ovules is the result of PCD by massive autophagy in the megagametophyte cells. In a few other sterile ovules, sterility is due to the delayed or the absence of megagametophyte development.
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Affiliation(s)
| | - Bárbara de Sá-Haiad
- Departamento de Botânica, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, 22940-040, Brazil
| | | | - Silvia Rodrigues Machado
- Departamento de Botânica, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, São Paulo, SP, 18618-000, Brazil
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Ueno N, Nihei S, Miyakawa N, Hirasawa T, Kanekatsu M, Marubashi W, van Doorn WG, Yamada T. Time course of programmed cell death, which included autophagic features, in hybrid tobacco cells expressing hybrid lethality. Plant Cell Rep 2016; 35:2475-2488. [PMID: 27585575 DOI: 10.1007/s00299-016-2048-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 08/27/2016] [Indexed: 06/06/2023]
Abstract
KEY MESSAGE PCD with features of vacuolar cell death including autophagy-related features were detected in hybrid tobacco cells, and detailed time course of features of vacuolar cell death were established. A type of interspecific Nicotiana hybrid, Nicotiana suaveolens × N. tabacum exhibits temperature-sensitive lethality. This lethality results from programmed cell death (PCD) in hybrid seedlings, but this PCD occurs only in seedlings and suspension-cultured cells grown at 28 °C, not those grown at 36 °C. Plant PCD can be classified as vacuolar cell death or necrotic cell death. Induction of autophagy, vacuolar membrane collapse and actin disorganization are each known features of vacuolar cell death, but observed cases of PCD showing all these features simultaneously are rare. In this study, these features of vacuolar cell death were evident in hybrid tobacco cells expressing hybrid lethality. Ion leakage, plasma membrane disruption, increased activity of vacuolar processing enzyme, vacuolar membrane collapse, and formation of punctate F-actin foci were each evident in these cells. Transmission electron microscopy revealed that macroautophagic structures formed and tonoplasts ruptured in these cells. The number of cells that contained monodansylcadaverine (MDC)-stained structures and the abundance of nine autophagy-related gene transcripts increased just before cell death at 28 °C; these features were not evident at 36 °C. We assessed whether an autophagic inhibitor, wortmannin (WM), influenced lethality in hybrid cells. After the hybrid cell began to die, WM suppressed increases in ion leakage and cell deaths, and it decreased the number of cells containing MDC-stained structures. These results showed that several features indicative of autophagy and vacuolar cell death were evident in the hybrid tobacco cells subject to lethality. In addition, we documented a detailed time course of these vacuolar cell death features.
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Affiliation(s)
- Naoya Ueno
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Saori Nihei
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Naoto Miyakawa
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Tadashi Hirasawa
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
- Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Motoki Kanekatsu
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Wataru Marubashi
- Faculty of Agricultural Science, Meiji University, Kanagawa, Japan
| | - Wouter G van Doorn
- Mann Laboratory, Department of Plant Sciences, University of California, Davis, CA, USA
- Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Tokyo, Japan
| | - Tetsuya Yamada
- United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, Tokyo, Japan.
- Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
- Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Tokyo, Japan.
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