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13 pages, 2815 KiB

Open AccessArticle

Effect of Paternal Genome Excess on the Developmental and Gene Expression Profiles of Polyspermic Zygotes in Rice

by Ryouya Deushi, Erika Toda, Shizuka Koshimizu, Kentaro Yano and Takashi Okamoto

Plants 2021, 10(2), 255; https://doi.org/10.3390/plants10020255 - 28 Jan 2021

Cited by 4 | Viewed by 2691

Abstract

Polyploid zygotes with a paternal gamete/genome excess exhibit arrested development, whereas polyploid zygotes with a maternal excess develop normally. These observations indicate that paternal and maternal genomes synergistically influence zygote development via distinct functions. In this study, to clarify how paternal genome excess [...] Read more.

Polyploid zygotes with a paternal gamete/genome excess exhibit arrested development, whereas polyploid zygotes with a maternal excess develop normally. These observations indicate that paternal and maternal genomes synergistically influence zygote development via distinct functions. In this study, to clarify how paternal genome excess affects zygotic development, the developmental and gene expression profiles of polyspermic rice zygotes were analyzed. The results indicated that polyspermic zygotes were mostly arrested at the one-cell stage after karyogamy had completed. Through comparison of transcriptomes between polyspermic zygotes and diploid zygotes, 36 and 43 genes with up-regulated and down-regulated expression levels, respectively, were identified in the polyspermic zygotes relative to the corresponding expression in the diploid zygotes. Notably, OsASGR-BBML1, which encodes an AP2 transcription factor possibly involved in initiating rice zygote development, was expressed at a much lower level in the polyspermic zygotes than in the diploid zygotes. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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14 pages, 8449 KiB

Open AccessArticle

Indirect Somatic Embryogenesis and Cryopreservation of Agave tequilana Weber Cultivar ‘Chato’

by Lourdes Delgado-Aceves, María Teresa González-Arnao, Fernando Santacruz-Ruvalcaba, Raquel Folgado and Liberato Portillo

Plants 2021, 10(2), 249; https://doi.org/10.3390/plants10020249 - 28 Jan 2021

Cited by 12 | Viewed by 4129

Abstract

Agave tequilana Weber cultivar ‘Chato’ represents an important genetic supply of wild severely in decline populations of ‘Chato’ for breeding and transformation programs. In this work, the indirect somatic embryogenesis and cryopreservation of Somatic Embryos (SEs) were investigated using the ‘Chato’ cultivar as [...] Read more.

Agave tequilana Weber cultivar ‘Chato’ represents an important genetic supply of wild severely in decline populations of ‘Chato’ for breeding and transformation programs. In this work, the indirect somatic embryogenesis and cryopreservation of Somatic Embryos (SEs) were investigated using the ‘Chato’ cultivar as a study case. Methods: Embryogenic calli were induced by the cultivation of 1 cm of young leaves from in vitro plants on MS semisolid medium supplemented with 24.84, 33.13, 41.41, 49.69, and 57.98 μM 4-amino-3,5,6-trichloro-2- pyridinecarboxylic acid (picloram) in combination with 2.21, 3.32, and 4.43 μM 6-benzylaminopurine (BAP). The origin and structure of formed SEs were verified by histological analysis. Cryopreservation studies of SEs were performed following the V-cryoplate technique and using for dehydration two vitrification solutions (PVS2 and PVS3). Results: The highest average (52.43 ± 5.74) of produced SEs and the Embryo Forming Capacity (estimated index 52.43) were obtained using 49.69 µM picloram and 3.32 µM BAP in the culture medium. The highest post-cryopreservation regrowth (83%) and plant conversion rate (around 70%) were achieved with PVS2 at 0 °C for 15 min. Conclusion: Our work provides new advances about somatic embryogenesis in Agave and reports the first results on cryopreservation of SEs of this species. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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20 pages, 61128 KiB

Open AccessArticle

Secondary Somatic Embryogenesis in Centaurium erythraea Rafn

by Milica D. Bogdanović, Katarina B. Ćuković, Angelina R. Subotić, Milan B. Dragićević, Ana D. Simonović, Biljana K. Filipović and Slađana I. Todorović

Plants 2021, 10(2), 199; https://doi.org/10.3390/plants10020199 - 21 Jan 2021

Cited by 13 | Viewed by 5726

Abstract

Somatic embryogenesis (SE) is a developmental process during which plant somatic cells, under suitable conditions, produce embryogenic cells that develop into somatic embryos (se). SE is the most important method for plant propagation in vitro, having both fundamental and applicative significance. [...] Read more.

Somatic embryogenesis (SE) is a developmental process during which plant somatic cells, under suitable conditions, produce embryogenic cells that develop into somatic embryos (se). SE is the most important method for plant propagation in vitro, having both fundamental and applicative significance. SE can be induced from different tissues and organs, but when se are used as explants, the process is recognized as secondary or cyclic SE. We induced secondary SE in Centaurium erythraea by application of 2,4-dichlorophenoxyacetic acid (2,4-D) and N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU). A medium containing 0.1 mgL⁻¹ 2,4-D and 0.25 mgL⁻¹ CPPU was optimal in terms of the number of primary SE explants forming se, the number of well-developed se per explant, and morphological appearance of the obtained se. These concentrations allowed SE to progress through three cycles, whereas at higher concentrations of 0.2 mgL⁻¹ 2,4-D and 0.5 mgL⁻¹ CPPU, only two cycles were achieved. Histological analysis revealed that secondary se are formed both directly and indirectly. Secondary SE readily germinated and converted into plantlets. Induction of cyclic SE contributes to the conservation efforts of this endangered medicinal plant and expands the spectrum of in vitro developmental pathways described in centaury—an emerging model in developmental biology. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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20 pages, 5304 KiB

Open AccessArticle

Early Low-Fluence Red Light or Darkness Modulates the Shoot Regeneration Capacity of Excised Arabidopsis Roots

by Xi Wei, Yanpeng Ding, Ye Wang, Fuguang Li and Xiaoyang Ge

Plants 2020, 9(10), 1378; https://doi.org/10.3390/plants9101378 - 16 Oct 2020

Cited by 3 | Viewed by 3320

Abstract

In plants, light is an important environmental signal that induces meristem development and interacts with endogenous signals, including hormones. We found that treatment with 24 h of low-fluence red light (24 h R) or 24 h of darkness (24 h D) following root [...] Read more.

In plants, light is an important environmental signal that induces meristem development and interacts with endogenous signals, including hormones. We found that treatment with 24 h of low-fluence red light (24 h R) or 24 h of darkness (24 h D) following root excision greatly increased the frequency of shoot generation, while continuous low-fluence red light in callus and shoot induction stages blocked the explants’ ability to generate shoots. Shoot generation ability was closely associated with WUS expression and distribution pattern. 1-N-naphthylphtalamic acid (NPA) disrupted the dynamic distribution of the WUS signal induced by early 24 h R treatment, and NPA plus 24 R treatment increased the average shoot number compared with early 24 h R alone. Transcriptome analysis revealed that differentially expressed genes involved in meristem development and hormone signal pathways were significantly enriched during 24 R or 24 D induced shoot regeneration, where early 24 h R or 24 h D treatment upregulated expression of WOX5, LBD16, LBD18 and PLT3 to promote callus initiation and formation of root primordia, and also activated WUS, STM, CUC1 and CUC2 expression, leading to initiation of the shoot apical meristem (SAM). This finding demonstrates that early exposure of explants to transient low-fluence red light or darkness modulates the expression of marker genes related with callus development and shoot regeneration, and dynamic distribution of WUS, leading to an increased ability to generate shoots. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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8 pages, 1459 KiB

Open AccessReview

A Quarter Century History of ATML1 Gene Research

by Hiroyuki Iida and Shinobu Takada

Plants 2021, 10(2), 290; https://doi.org/10.3390/plants10020290 - 3 Feb 2021

Cited by 5 | Viewed by 2666

Abstract

The cloning of the ATML1 gene, encoding an HD-ZIP class IV transcription factor, was first reported in 1996. Because ATML1 mRNA was preferentially detected in the shoot epidermis, cis-regulatory sequences of ATML1 have been used to drive gene expression in the outermost cells [...] Read more.

The cloning of the ATML1 gene, encoding an HD-ZIP class IV transcription factor, was first reported in 1996. Because ATML1 mRNA was preferentially detected in the shoot epidermis, cis-regulatory sequences of ATML1 have been used to drive gene expression in the outermost cells of the shoot apical meristem and leaves, even before the function of ATML1 was understood. Later studies revealed that ATML1 is required for developmental processes related to shoot epidermal specification and differentiation. Consistent with its central role in epidermal development, ATML1 activity has been revealed to be restricted to the outermost cells via several regulatory mechanisms. In this review, we look back on the history of ATML1 research and provide a perspective for future studies. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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19 pages, 2136 KiB

Open AccessEditor’s ChoiceReview

Somatic Embryogenesis in Centaurium erythraea Rafn—Current Status and Perspectives: A Review

by Ana D. Simonović, Milana M. Trifunović-Momčilov, Biljana K. Filipović, Marija P. Marković, Milica D. Bogdanović and Angelina R. Subotić

Plants 2021, 10(1), 70; https://doi.org/10.3390/plants10010070 - 31 Dec 2020

Cited by 19 | Viewed by 4672

Abstract

Centaurium erythraea (centaury) is a traditionally used medicinal plant, with a spectrum of secondary metabolites with confirmed healing properties. Centaury is an emerging model in plant developmental biology due to its vigorous regenerative potential and great developmental plasticity when cultured in vitro. Hereby, [...] Read more.

Centaurium erythraea (centaury) is a traditionally used medicinal plant, with a spectrum of secondary metabolites with confirmed healing properties. Centaury is an emerging model in plant developmental biology due to its vigorous regenerative potential and great developmental plasticity when cultured in vitro. Hereby, we review nearly two decades of research on somatic embryogenesis (SE) in centaury. During SE, somatic cells are induced by suitable culture conditions to express their totipotency, acquire embryogenic characteristics, and eventually give rise to somatic embryos. When SE is initiated from centaury root explants, the process occurs spontaneously (on hormone-free medium), directly (without the callusing phase), and the somatic embryos are of unicellular origin. SE from leaf explants has to be induced by plant growth regulators and is indirect (preceded by callusing). Histological observations and culture conditions are compared in these two systems. The changes in antioxidative enzymes were followed during SE from the leaf explants. Special focus is given to the role of arabinogalactan proteins during SE, which were analyzed using a variety of approaches. The newest and preliminary results, including centaury transcriptome, novel potential SE markers, and novel types of arabinogalactan proteins, are discussed as perspectives of centaury research. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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7 pages, 2340 KiB

Open AccessTechnical Note

A ClearSee-Based Clearing Protocol for 3D Visualization of Arabidopsis thaliana Embryos

by Ayame Imoto, Mizuki Yamada, Takumi Sakamoto, Airi Okuyama, Takashi Ishida, Shinichiro Sawa and Mitsuhiro Aida

Plants 2021, 10(2), 190; https://doi.org/10.3390/plants10020190 - 20 Jan 2021

Cited by 15 | Viewed by 5208

Abstract

Tissue clearing methods combined with confocal microscopy have been widely used for studying developmental biology. In plants, ClearSee is a reliable clearing method that is applicable to a wide range of tissues and is suitable for gene expression analysis using fluorescent reporters, but [...] Read more.

Tissue clearing methods combined with confocal microscopy have been widely used for studying developmental biology. In plants, ClearSee is a reliable clearing method that is applicable to a wide range of tissues and is suitable for gene expression analysis using fluorescent reporters, but its application to the Arabidopsis thaliana embryo, a model system to study morphogenesis and pattern formation, has not been described in the original literature. Here, we describe a ClearSee-based clearing protocol which is suitable for obtaining 3D images of Arabidopsis thaliana embryos. The method consists of embryo dissection, fixation, washing, clearing, and cell wall staining and enables high-quality 3D imaging of embryo morphology and expression of fluorescent reporters with the cellular resolution. Our protocol provides a reliable method that is applicable to the analysis of morphogenesis and gene expression patterns in Arabidopsis thaliana embryos. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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8 pages, 1401 KiB

Open AccessTechnical Note

Detection of Embryonic Suspensor Cell Death by Whole-Mount TUNEL Assay in Tobacco

by Ce Shi, Pan Luo, Peng Zhao and Meng-Xiang Sun

Plants 2020, 9(9), 1196; https://doi.org/10.3390/plants9091196 - 12 Sep 2020

Cited by 2 | Viewed by 5475

Abstract

Embryonic suspensor in angiosperms is a short-lived structure that connects the embryo to surrounding maternal tissues, which is necessary for early embryogenesis. Timely degeneration via programed cell death is the most distinct feature of the suspensor during embryogenesis. Therefore, the molecular mechanism regulating [...] Read more.

Embryonic suspensor in angiosperms is a short-lived structure that connects the embryo to surrounding maternal tissues, which is necessary for early embryogenesis. Timely degeneration via programed cell death is the most distinct feature of the suspensor during embryogenesis. Therefore, the molecular mechanism regulating suspensor cell death is worth in-depth study for embryonic development. However, this process can hardly be detected using conventional methods since early embryos are deeply embedded in the seed coats and inaccessible through traditional tissue section. Hence, it is necessary to develop a reliable protocol for terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) analysis using limited living early embryos. Here, we provide a detailed protocol for the whole-mount detection of suspensor cell death using a TUNEL system in tobacco. This method is especially useful for the direct and rapid detection of the spatial-temporal characters of programed cell death during embryogenesis, as well as for the diminishment of the artifacts during material treatment by traditional methods. Full article

(This article belongs to the Special Issue Plant Embryogenesis)

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