Editorial

3 pages, 186 KiB

Open AccessEditorial

by Jen-Tsung Chen and Parviz Heidari

Int. J. Mol. Sci. 2021, 22(15), 8007; https://doi.org/10.3390/ijms22158007 - 27 Jul 2021

Viewed by 1573

Plant cell signaling is an intensive research topic in which reductionist can be achieved when we investigate the systems of model plants [...] Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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15 pages, 2808 KiB

Open AccessArticle

Evolutionary Analysis and Functional Identification of Ancient Brassinosteroid Receptors in Ceratopteris richardii

by Bowen Zheng, Kaixin Xing, Jiaojiao Zhang, Hui Liu, Khawar Ali, Wenjuan Li, Qunwei Bai and Hongyan Ren

Int. J. Mol. Sci. 2022, 23(12), 6795; https://doi.org/10.3390/ijms23126795 - 18 Jun 2022

Cited by 7 | Viewed by 2143

Abstract

Phytohormones play an important role in the adaptive evolution of terrestrial plants. Brassinosteroids (BRs) are essential hormones that regulate multiple aspects of plant growth and development in angiosperms, but the presence of BR signaling in non-seed plants such as ferns remains unknown. Here, [...] Read more.

Phytohormones play an important role in the adaptive evolution of terrestrial plants. Brassinosteroids (BRs) are essential hormones that regulate multiple aspects of plant growth and development in angiosperms, but the presence of BR signaling in non-seed plants such as ferns remains unknown. Here, we found that BR promotes the growth of Ceratopteris richardii, while the synthetic inhibitor PCZ inhibits the growth. Using full-length transcriptome sequencing, we identified four BRI1-like receptors. By constructing chimeric receptors, we found that the kinase domains of these four receptors could trigger BR downstream signaling. Further, the extracellular domains of two receptors were functionally interchangeable with that of BRI1. In addition, we identified a co-receptor, CtSERK1, that could phosphorylate with CtBRL2s in vitro. Together, these proved the presence of a receptor complex in Ceratopteris richardii that might perceive BR and activate downstream hormone signaling. Our results shed light on the biological and molecular mechanisms of BR signaling in ferns and the role of BR hormone signaling in the adaptive evolution of terrestrial plants. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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17 pages, 3636 KiB

Open AccessArticle

KOMPEITO, an Atypical Arabidopsis Rhomboid-Related Gene, Is Required for Callose Accumulation and Pollen Wall Development

by Masahiro M. Kanaoka, Kentaro K. Shimizu, Bo Xie, Sinisa Urban, Matthew Freeman, Zonglie Hong and Kiyotaka Okada

Int. J. Mol. Sci. 2022, 23(11), 5959; https://doi.org/10.3390/ijms23115959 - 25 May 2022

Cited by 4 | Viewed by 2189

Abstract

Fertilization is a key event for sexually reproducing plants. Pollen–stigma adhesion, which is the first step in male–female interaction during fertilization, requires proper pollen wall patterning. Callose, which is a β-1.3-glucan, is an essential polysaccharide that is required for pollen development and pollen [...] Read more.

Fertilization is a key event for sexually reproducing plants. Pollen–stigma adhesion, which is the first step in male–female interaction during fertilization, requires proper pollen wall patterning. Callose, which is a β-1.3-glucan, is an essential polysaccharide that is required for pollen development and pollen wall formation. Mutations in CALLOSE SYNTHASE 5 (CalS5) disrupt male meiotic callose accumulation; however, how CalS5 activity and callose synthesis are regulated is not fully understood. In this paper, we report the isolation of a kompeito-1 (kom-1) mutant defective in pollen wall patterning and pollen–stigma adhesion in Arabidopsis thaliana. Callose was not accumulated in kom-1 meiocytes or microspores, which was very similar to the cals5 mutant. The KOM gene encoded a member of a subclass of Rhomboid serine protease proteins that lacked active site residues. KOM was localized to the Golgi apparatus, and both KOM and CalS5 genes were highly expressed in meiocytes. A 220 kDa CalS5 protein was detected in wild-type (Col-0) floral buds but was dramatically reduced in kom-1. These results suggested that KOM was required for CalS5 protein accumulation, leading to the regulation of meiocyte-specific callose accumulation and pollen wall formation. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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24 pages, 7046 KiB

Open AccessArticle

Crosstalk between the Arabidopsis Glutathione Peroxidase-Like 5 Isoenzyme (AtGPXL5) and Ethylene

by Riyazuddin Riyazuddin, Krisztina Bela, Péter Poór, Ágnes Szepesi, Edit Horváth, Gábor Rigó, László Szabados, Attila Fehér and Jolán Csiszár

Int. J. Mol. Sci. 2022, 23(10), 5749; https://doi.org/10.3390/ijms23105749 - 20 May 2022

Cited by 5 | Viewed by 1889

Abstract

Glutathione peroxidases (GPXs) are important antioxidant enzymes in animals. Plants contain GPX-like (GPXL) enzymes, which—in contrast to GPXs—contain cysteine in their active site instead of selenocysteine. Although several studies proved their importance in development and stress responses, their interaction with ethylene (ET) signalling [...] Read more.

Glutathione peroxidases (GPXs) are important antioxidant enzymes in animals. Plants contain GPX-like (GPXL) enzymes, which—in contrast to GPXs—contain cysteine in their active site instead of selenocysteine. Although several studies proved their importance in development and stress responses, their interaction with ethylene (ET) signalling is not known. Our aim was to investigate the involvement of AtGPXL5 in ET biosynthesis and/or signalling using Atgpxl5 mutant and AtGPXL5 cDNA-overexpressing (OX-AtGPXL5) lines. Four-day-old dark-grown Atgpxl5 seedlings had shorter hypocotyls and primary roots, while OX-AtGPXL5 seedlings exhibited a similar phenotype as wild type under normal conditions. Six-week-old OX-AtGPXL5 plants contained less H₂O₂ and malondialdehyde, but higher polyamine and similar ascorbate- and glutathione contents and redox potential (E_GSH) than the Col-0. One-day treatment with the ET-precursor 1-aminocyclopropane-1-carboxylic acid (ACC) induced the activity of glutathione- and thioredoxin peroxidases and some other ROS-processing enzymes. In the Atgpxl5 mutants, the E_GSH became more oxidised; parallelly, it produced more ethylene after the ACC treatment than other genotypes. Although the enhanced ET evolution measured in the Atgpxl5 mutant can be the result of the increased ROS level, the altered expression pattern of ET-related genes both in the Atgpxl5 and OX-AtGPXL5 plants suggests the interplay between AtGPXL5 and ethylene signalling. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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18 pages, 4405 KiB

Open AccessArticle

Engineering Chimeras by Fusing Plant Receptor-like Kinase EMS1 and BRI1 Reveals the Two Receptors’ Structural Specificity and Molecular Mechanisms

by Qunwei Bai, Chenxi Li, Lei Wu, Huan Liu, Hongyan Ren, Guishuang Li, Qiuling Wang, Guang Wu and Bowen Zheng

Int. J. Mol. Sci. 2022, 23(4), 2155; https://doi.org/10.3390/ijms23042155 - 15 Feb 2022

Cited by 6 | Viewed by 3245

Abstract

Brassinosteriods (BRs) are plant hormones essential for plant growth and development. The receptor-like kinase (RLK) BRI1 perceives BRs to initiate a well-known transduction pathway which finally activate the transcription factors BZR1/BES1 specifically regulating BR-mediated gene expression. The RLK EMS1 governs tapetum formation via [...] Read more.

Brassinosteriods (BRs) are plant hormones essential for plant growth and development. The receptor-like kinase (RLK) BRI1 perceives BRs to initiate a well-known transduction pathway which finally activate the transcription factors BZR1/BES1 specifically regulating BR-mediated gene expression. The RLK EMS1 governs tapetum formation via the same signaling pathway shared with BRI1. BRI1 and EMS1 have a common signal output, but the gene structural specificity and the molecular response remain unclear. In this study, we identified that the transmembrane (TM), intracellular juxtamembrane (iJM), kinase, and leucin-rich repeats 1-13 (LRR1-13) domains of EMS1 could replace the corresponding BRI1 domain to maintain the BR receptor function, whereas the extracellular juxtamembrane (eJM) and LRR1-14 domains could not, indicating that the LRR14-EJM domain conferred functional specificity to BRI1. We compared the kinase domains of EMS1 and BRI1, and found that EMS1’s kinase activity was weaker than BRI1’s. Further investigation of the specific phosphorylation sites in BRI1 and EMS1 revealed that the Y1052 site in the kinase domain was essential for the BRI1 biological function, but the corresponding site in EMS1 showed no effect on the biological function of EMS1, suggesting a site regulation difference in the two receptors. Furthermore, we showed that EMS1 shared the substrate BSKs with BRI1. Our study provides insight into the structural specificity and molecular mechanism of BRI1 and EMS1, as well as the origin and divergence of BR receptors. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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18 pages, 3187 KiB

Open AccessArticle

MiR1885 Regulates Disease Tolerance Genes in Brassica rapa during Early Infection with Plasmodiophora brassicae

by Parameswari Paul, Sushil Satish Chhapekar, Jana Jeevan Rameneni, Sang Heon Oh, Vignesh Dhandapani, Saminathan Subburaj, Sang-Yoon Shin, Nirala Ramchiary, Chanseok Shin, Su Ryun Choi and Yong Pyo Lim

Int. J. Mol. Sci. 2021, 22(17), 9433; https://doi.org/10.3390/ijms22179433 - 30 Aug 2021

Cited by 8 | Viewed by 2317

Abstract

Clubroot caused by Plasmodiophora brassicae is a severe disease of cruciferous crops that decreases crop quality and productivity. Several clubroot resistance-related quantitative trait loci and candidate genes have been identified. However, the underlying regulatory mechanism, the interrelationships among genes, and how genes are [...] Read more.

Clubroot caused by Plasmodiophora brassicae is a severe disease of cruciferous crops that decreases crop quality and productivity. Several clubroot resistance-related quantitative trait loci and candidate genes have been identified. However, the underlying regulatory mechanism, the interrelationships among genes, and how genes are regulated remain unexplored. MicroRNAs (miRNAs) are attracting attention as regulators of gene expression, including during biotic stress responses. The main objective of this study was to understand how miRNAs regulate clubroot resistance-related genes in P. brassicae-infected Brassica rapa. Two Brassica miRNAs, Bra-miR1885a and Bra-miR1885b, were revealed to target TIR-NBS genes. In non-infected plants, both miRNAs were expressed at low levels to maintain the balance between plant development and basal immunity. However, their expression levels increased in P. brassicae-infected plants. Both miRNAs down-regulated the expression of the TIR-NBS genes Bra019412 and Bra019410, which are located at a clubroot resistance-related quantitative trait locus. The Bra-miR1885-mediated down-regulation of both genes was detected for up to 15 days post-inoculation in the clubroot-resistant line CR Shinki and in the clubroot-susceptible line 94SK. A qRT-PCR analysis revealed Bra019412 expression was negatively regulated by miR1885. Both Bra019412 and Bra019410 were more highly expressed in CR Shinki than in 94SK; the same expression pattern was detected in multiple clubroot-resistant and clubroot-susceptible inbred lines. A 5′ rapid amplification of cDNA ends analysis confirmed the cleavage of Bra019412 by Bra-miR1885b. Thus, miR1885s potentially regulate TIR-NBS gene expression during P. brassicae infections of B. rapa. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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18 pages, 3945 KiB

Open AccessArticle

Putrescine Depletion Affects Arabidopsis Root Meristem Size by Modulating Auxin and Cytokinin Signaling and ROS Accumulation

by Ahmed M. Hashem, Simon Moore, Shangjian Chen, Chenchen Hu, Qing Zhao, Ibrahim Eid Elesawi, Yanni Feng, Jennifer F. Topping, Junli Liu, Keith Lindsey and Chunli Chen

Int. J. Mol. Sci. 2021, 22(8), 4094; https://doi.org/10.3390/ijms22084094 - 15 Apr 2021

Cited by 24 | Viewed by 3506

Abstract

Polyamines (PAs) dramatically affect root architecture and development, mainly by unknown mechanisms; however, accumulating evidence points to hormone signaling and reactive oxygen species (ROS) as candidate mechanisms. To test this hypothesis, PA levels were modified by progressively reducing ADC1/2 activity and Put levels, [...] Read more.

Polyamines (PAs) dramatically affect root architecture and development, mainly by unknown mechanisms; however, accumulating evidence points to hormone signaling and reactive oxygen species (ROS) as candidate mechanisms. To test this hypothesis, PA levels were modified by progressively reducing ADC1/2 activity and Put levels, and then changes in root meristematic zone (MZ) size, ROS, and auxin and cytokinin (CK) signaling were investigated. Decreasing putrescine resulted in an interesting inverted-U-trend in primary root growth and a similar trend in MZ size, and differential changes in putrescine (Put), spermidine (Spd), and combined spermine (Spm) plus thermospermine (Tspm) levels. At low Put concentrations, ROS accumulation increased coincidently with decreasing MZ size, and treatment with ROS scavenger KI partially rescued this phenotype. Analysis of double AtrbohD/F loss-of-function mutants indicated that NADPH oxidases were not involved in H₂O₂ accumulation and that elevated ROS levels were due to changes in PA back-conversion, terminal catabolism, PA ROS scavenging, or another pathway. Decreasing Put resulted in a non-linear trend in auxin signaling, whereas CK signaling decreased, re-balancing auxin and CK signaling. Different levels of Put modulated the expression of PIN1 and PIN2 auxin transporters, indicating changes to auxin distribution. These data strongly suggest that PAs modulate MZ size through both hormone signaling and ROS accumulation in Arabidopsis. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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12 pages, 1596 KiB

Open AccessArticle

Characterization of the FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 Homolog SlFKF1 in Tomato as a Model for Plants with Fleshy Fruit

by Tomoki Shibuya, Manabu Nishiyama, Kazuhisa Kato and Yoshinori Kanayama

Int. J. Mol. Sci. 2021, 22(4), 1735; https://doi.org/10.3390/ijms22041735 - 09 Feb 2021

Cited by 12 | Viewed by 2031

Abstract

FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1) is a blue-light receptor whose function is related to flowering promotion under long-day conditions in Arabidopsis thaliana. However, information about the physiological role of FKF1 in day-neutral plants and even the physiological role other than photoperiodic [...] Read more.

FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1) is a blue-light receptor whose function is related to flowering promotion under long-day conditions in Arabidopsis thaliana. However, information about the physiological role of FKF1 in day-neutral plants and even the physiological role other than photoperiodic flowering is lacking. Thus, the FKF1 homolog SlFKF1 was investigated in tomato, a day-neutral plant and a useful model for plants with fleshy fruit. It was confirmed that SlFKF1 belongs to the FKF1 group by phylogenetic tree analysis. The high sequence identity with A. thaliana FKF1, the conserved amino acids essential for function, and the similarity in the diurnal change in expression suggested that SlFKF1 may have similar functions to A. thaliana FKF1. CONSTANS (CO) is a transcription factor regulated by FKF1 and is responsible for the transcription of genes downstream of CO. cis-Regulatory elements targeted by CO were found in the promoter region of SINGLE FLOWER TRUSS (SFT) and RIN, which are involved in the regulation of flowering and fruit ripening, respectively. The blue-light effects on SlFKF1 expression, flowering, and fruit lycopene concentration have been observed in this study and previous studies. It was confirmed in RNA interference lines that the low expression of SlFKF1 is associated with late flowering with increased leaflets and low lycopene concentrations. This study sheds light on the various physiological roles of FKF1 in plants. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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12 pages, 1888 KiB

Open AccessArticle

Mitochondrial Transcription Termination Factor 27 Is Required for Salt Tolerance in Arabidopsis thaliana

by Deyuan Jiang, Jian Chen, Zhihong Zhang and Xin Hou

Int. J. Mol. Sci. 2021, 22(3), 1466; https://doi.org/10.3390/ijms22031466 - 02 Feb 2021

Cited by 6 | Viewed by 2780

Abstract

In plants, mTERF proteins are primarily found in mitochondria and chloroplasts. Studies have identified several mTERF proteins that affect plant development, respond to abiotic stresses, and regulate organellar gene expression, but the functions and underlying mechanisms of plant mTERF proteins remain largely unknown. [...] Read more.

In plants, mTERF proteins are primarily found in mitochondria and chloroplasts. Studies have identified several mTERF proteins that affect plant development, respond to abiotic stresses, and regulate organellar gene expression, but the functions and underlying mechanisms of plant mTERF proteins remain largely unknown. Here, we investigated the function of Arabidopsis mTERF27 using molecular genetic, cytological, and biochemical approaches. Arabidopsis mTERF27 had four mTERF motifs and was evolutionarily conserved from moss to higher plants. The phenotype of the mTERF27-knockout mutant mterf27 did not differ obviously from that of the wild-type under normal growth conditions but was hypersensitive to salt stress. mTERF27 was localized to the mitochondria, and the transcript levels of some mitochondrion-encoded genes were reduced in the mterf27 mutant. Importantly, loss of mTERF27 function led to developmental defects in the mitochondria under salt stress. Furthermore, mTERF27 formed homomers and directly interacted with multiple organellar RNA editing factor 8 (MORF8). Thus, our results indicated that mTERF27 is likely crucial for mitochondrial development under salt stress, and that this protein may be a member of the protein interaction network regulating mitochondrial gene expression. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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27 pages, 4210 KiB

Open AccessArticle

From Spaceflight to Mars g-Levels: Adaptive Response of A. Thaliana Seedlings in a Reduced Gravity Environment Is Enhanced by Red-Light Photostimulation

by Alicia Villacampa, Malgorzata Ciska, Aránzazu Manzano, Joshua P. Vandenbrink, John Z. Kiss, Raúl Herranz and F. Javier Medina

Int. J. Mol. Sci. 2021, 22(2), 899; https://doi.org/10.3390/ijms22020899 - 18 Jan 2021

Cited by 22 | Viewed by 4220

Abstract

The response of plants to the spaceflight environment and microgravity is still not well understood, although research has increased in this area. Even less is known about plants’ response to partial or reduced gravity levels. In the absence of the directional cues provided [...] Read more.

The response of plants to the spaceflight environment and microgravity is still not well understood, although research has increased in this area. Even less is known about plants’ response to partial or reduced gravity levels. In the absence of the directional cues provided by the gravity vector, the plant is especially perceptive to other cues such as light. Here, we investigate the response of Arabidopsis thaliana 6-day-old seedlings to microgravity and the Mars partial gravity level during spaceflight, as well as the effects of red-light photostimulation by determining meristematic cell growth and proliferation. These experiments involve microscopic techniques together with transcriptomic studies. We demonstrate that microgravity and partial gravity trigger differential responses. The microgravity environment activates hormonal routes responsible for proliferation/growth and upregulates plastid/mitochondrial-encoded transcripts, even in the dark. In contrast, the Mars gravity level inhibits these routes and activates responses to stress factors to restore cell growth parameters only when red photostimulation is provided. This response is accompanied by upregulation of numerous transcription factors such as the environmental acclimation-related WRKY-domain family. In the long term, these discoveries can be applied in the design of bioregenerative life support systems and space farming. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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21 pages, 5485 KiB

Open AccessArticle

Molecular Analysis of 14-3-3 Genes in Citrus sinensis and Their Responses to Different Stresses

by Shiheng Lyu, Guixin Chen, Dongming Pan, Jianjun Chen and Wenqin She

Int. J. Mol. Sci. 2021, 22(2), 568; https://doi.org/10.3390/ijms22020568 - 08 Jan 2021

Cited by 13 | Viewed by 2506

Abstract

14-3-3 proteins (14-3-3s) are among the most important phosphorylated molecules playing crucial roles in regulating plant development and defense responses to environmental constraints. No report thus far has documented the gene family of 14-3-3s in Citrus sinensis and their roles in response to [...] Read more.

14-3-3 proteins (14-3-3s) are among the most important phosphorylated molecules playing crucial roles in regulating plant development and defense responses to environmental constraints. No report thus far has documented the gene family of 14-3-3s in Citrus sinensis and their roles in response to stresses. In this study, nine 14-3-3 genes, designated as CitGF14s (CitGF14a through CitGF14i) were identified from the latest C. sinensis genome. Phylogenetic analysis classified them into ε-like and non-ε groups, which were supported by gene structure analysis. The nine CitGF14s were located on five chromosomes, and none had duplication. Publicly available RNA-Seq raw data and microarray databases were mined for 14-3-3 expression profiles in different organs of citrus and in response to biotic and abiotic stresses. RT-qPCR was used for further examining spatial expression patterns of CitGF14s in citrus and their temporal expressions in one-year-old C. sinensis “Xuegan” plants after being exposed to different biotic and abiotic stresses. The nine CitGF14s were expressed in eight different organs with some isoforms displayed tissue-specific expression patterns. Six of the CitGF14s positively responded to citrus canker infection (Xanthomonas axonopodis pv. citri). The CitGF14s showed expressional divergence after phytohormone application and abiotic stress treatments, suggesting that 14-3-3 proteins are ubiquitous regulators in C. sinensis. Using the yeast two-hybrid assay, CitGF14a, b, c, d, g, and h were found to interact with CitGF14i proteins to form a heterodimer, while CitGF14i interacted with itself to form a homodimer. Further analysis of CitGF14s co-expression and potential interactors established a 14-3-3s protein interaction network. The established network identified 14-3-3 genes and several candidate clients which may play an important role in developmental regulation and stress responses in this important fruit crop. This is the first study of 14-3-3s in citrus, and the established network may help further investigation of the roles of 14-3-3s in response to abiotic and biotic constraints. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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20 pages, 3344 KiB

Open AccessArticle

Annexin 1 Is a Component of eATP-Induced Cytosolic Calcium Elevation in Arabidopsis thaliana Roots

by Amirah Mohammad-Sidik, Jian Sun, Ryoung Shin, Zhizhong Song, Youzheng Ning, Elsa Matthus, Katie A. Wilkins and Julia M. Davies

Int. J. Mol. Sci. 2021, 22(2), 494; https://doi.org/10.3390/ijms22020494 - 06 Jan 2021

Cited by 23 | Viewed by 3844

Abstract

Extracellular ATP (eATP) has long been established in animals as an important signalling molecule but this is less understood in plants. The identification of Arabidopsis thaliana DORN1 (Does Not Respond to Nucleotides) as the first plant eATP receptor has shown that it is [...] Read more.

Extracellular ATP (eATP) has long been established in animals as an important signalling molecule but this is less understood in plants. The identification of Arabidopsis thaliana DORN1 (Does Not Respond to Nucleotides) as the first plant eATP receptor has shown that it is fundamental to the elevation of cytosolic free Ca²⁺ ([Ca²⁺]_cyt) as a possible second messenger. eATP causes other downstream responses such as increase in reactive oxygen species (ROS) and nitric oxide, plus changes in gene expression. The plasma membrane Ca²⁺ influx channels involved in eATP-induced [Ca²⁺]_cyt increase remain unknown at the genetic level. Arabidopsis thaliana Annexin 1 has been found to mediate ROS-activated Ca²⁺ influx in root epidermis, consistent with its operating as a transport pathway. In this study, the loss of function Annexin 1 mutant was found to have impaired [Ca²⁺]_cyt elevation in roots in response to eATP or eADP. Additionally, this annexin was implicated in modulating eATP-induced intracellular ROS accumulation in roots as well as expression of eATP-responsive genes. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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17 pages, 6346 KiB

Open AccessArticle

OsPP2C09 Is a Bifunctional Regulator in Both ABA-Dependent and Independent Abiotic Stress Signaling Pathways

by Myung Ki Min, Rigyeong Kim, Woo-Jong Hong, Ki-Hong Jung, Jong-Yeol Lee and Beom-Gi Kim

Int. J. Mol. Sci. 2021, 22(1), 393; https://doi.org/10.3390/ijms22010393 - 01 Jan 2021

Cited by 16 | Viewed by 2831

Abstract

Clade A Type 2C protein phosphatases (PP2CAs) negatively regulate abscisic acid (ABA) signaling and have diverse functions in plant development and in response to various stresses. In this study, we showed that overexpression of the rice ABA receptor OsPYL/RCAR3 reduces the growth retardation [...] Read more.

Clade A Type 2C protein phosphatases (PP2CAs) negatively regulate abscisic acid (ABA) signaling and have diverse functions in plant development and in response to various stresses. In this study, we showed that overexpression of the rice ABA receptor OsPYL/RCAR3 reduces the growth retardation observed in plants exposed to osmotic stress. By contrast, overexpression of the OsPYL/RCAR3-interacting protein OsPP2C09 rendered plant growth more sensitive to osmotic stress. We tested whether OsPP2CAs activate an ABA-independent signaling cascade by transfecting rice protoplasts with luciferase reporters containing the drought-responsive element (DRE) or ABA-responsive element (ABRE). We observed that OsPP2CAs activated gene expression via the cis-acting drought-responsive element. In agreement with this observation, transcriptome analysis of plants overexpressing OsPP2C09 indicated that OsPP2C09 induces the expression of genes whose promoters contain DREs. Further analysis showed that OsPP2C09 interacts with DRE-binding (DREB) transcription factors and activates reporters containing DRE. We conclude that, through activating DRE-containing promoters, OsPP2C09 positively regulates the drought response regulon and activates an ABA-independent signaling pathway. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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21 pages, 7637 KiB

Open AccessArticle

Modification of Serine 1040 of SIBRI1 Increases Fruit Yield by Enhancing Tolerance to Heat Stress in Tomato

by Shufen Wang, Tixu Hu, Aijuan Tian, Bote Luo, Chenxi Du, Siwei Zhang, Shuhua Huang, Fei Zhang and Xiaofeng Wang

Int. J. Mol. Sci. 2020, 21(20), 7681; https://doi.org/10.3390/ijms21207681 - 16 Oct 2020

Cited by 6 | Viewed by 2045

Abstract

High temperature is a major environmental factor that adversely affects plant growth and production. SlBRI1 is a critical receptor in brassinosteroid signalling, and its phosphorylation sites have differential functions in plant growth and development. However, the roles of the phosphorylation sites of SIBRI1 [...] Read more.

High temperature is a major environmental factor that adversely affects plant growth and production. SlBRI1 is a critical receptor in brassinosteroid signalling, and its phosphorylation sites have differential functions in plant growth and development. However, the roles of the phosphorylation sites of SIBRI1 in stress tolerance are unknown. In this study, we investigated the biological functions of the phosphorylation site serine 1040 (Ser-1040) of SlBRI1 in tomato. Phenotype analysis indicated that transgenic tomato harbouring SlBRI1 dephosphorylated at Ser-1040 showed increased tolerance to heat stress, exhibiting better plant growth and plant yield under high temperature than transgenic lines expressing SlBRI1 or SlBRI1 phosphorylated at Ser-1040. Biochemical and physiological analyses further showed that antioxidant activity, cell membrane integrity, osmo-protectant accumulation, photosynthesis and transcript levels of heat stress defence genes were all elevated in tomato plants harbouring SlBRI1 dephosphorylated at Ser-1040, and the autophosphorylation level of SlBRI1 was inhibited when SlBRI1 dephosphorylated at Ser-1040. Taken together, our results demonstrate that the phosphorylation site Ser-1040 of SlBRI1 affects heat tolerance, leading to improved plant growth and yield under high-temperature conditions. Our results also indicate the promise of phosphorylation site modification as an approach for protecting crop yields from high-temperature stress. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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15 pages, 24279 KiB

Open AccessArticle

Cell Type-Specific Imaging of Calcium Signaling in Arabidopsis thaliana Seedling Roots Using GCaMP3

by William Krogman, J. Alan Sparks and Elison B. Blancaflor

Int. J. Mol. Sci. 2020, 21(17), 6385; https://doi.org/10.3390/ijms21176385 - 02 Sep 2020

Cited by 13 | Viewed by 4300

Abstract

Cytoplasmic calcium ([Ca²⁺]_cyt) is a well-characterized second messenger in eukaryotic cells. An elevation in [Ca²⁺]_cyt levels is one of the earliest responses in plant cells after exposure to a range of environmental stimuli. Advances in understanding [...] Read more.

Cytoplasmic calcium ([Ca²⁺]_cyt) is a well-characterized second messenger in eukaryotic cells. An elevation in [Ca²⁺]_cyt levels is one of the earliest responses in plant cells after exposure to a range of environmental stimuli. Advances in understanding the role of [Ca²⁺]_cyt in plant development has been facilitated by the use of genetically-encoded reporters such as GCaMP. Most of these studies have relied on promoters such as Cauliflower Mosaic Virus (35S) and Ubiquitin10 (UBQ10) to drive expression of GCaMP in all cell/tissue types. Plant organs such as roots consist of various cell types that likely exhibit unique [Ca²⁺]_cyt responses to exogenous and endogenous signals. However, few studies have addressed this question. Here, we introduce a set of Arabidopsis thaliana lines expressing GCaMP3 in five root cell types including the columella, endodermis, cortex, epidermis, and trichoblasts. We found similarities and differences in the [Ca²⁺]_cyt signature among these root cell types when exposed to adenosine tri-phosphate (ATP), glutamate, aluminum, and salt, which are known to trigger [Ca²⁺]_cyt increases in root cells. These cell type-targeted GCaMP3 lines provide a new resource that should enable more in depth studies that address how a particular environmental stimulus is linked to specific root developmental pathways via [Ca²⁺]_cyt. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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12 pages, 3457 KiB

Open AccessArticle

Dephosphorylation of LjMPK6 by Phosphatase LjPP2C is Involved in Regulating Nodule Organogenesis in Lotus japonicus

by Zhongyuan Yan, Jingjing Cao, Qiuling Fan, Hongmin Chao, Xiaomin Guan, Zhongming Zhang and Deqiang Duanmu

Int. J. Mol. Sci. 2020, 21(15), 5565; https://doi.org/10.3390/ijms21155565 - 03 Aug 2020

Cited by 6 | Viewed by 2456

Abstract

The mitogen-activated protein kinase (MAPK) LjMPK6 is a phosphorylation target of SIP2, a MAPK kinase that interacts with SymRK (symbiosis receptor-like kinase) for regulation of legume-rhizobia symbiosis. Both LjMPK6 and SIP2 are required for nodulation in Lotus japonicus. However, the dephosphorylation of [...] Read more.

The mitogen-activated protein kinase (MAPK) LjMPK6 is a phosphorylation target of SIP2, a MAPK kinase that interacts with SymRK (symbiosis receptor-like kinase) for regulation of legume-rhizobia symbiosis. Both LjMPK6 and SIP2 are required for nodulation in Lotus japonicus. However, the dephosphorylation of LjMPK6 and its regulatory components in nodule development remains unexplored. By yeast two-hybrid screening, we identified a type 2C protein phosphatase, LjPP2C, that specifically interacts with and dephosphorylates LjMPK6 in vitro. Physiological and biochemical assays further suggested that LjPP2C phosphatase is required for dephosphorylation of LjMPK6 in vivo and for fine-tuning nodule development after rhizobial inoculation. A non-phosphorylatable mutant variant LjMPK6 (T224A Y226F) could mimic LjPP2C functioning in MAPK dephosphorylation required for nodule development in hairy root transformed plants. Collectively, our study demonstrates that interaction with LjPP2C phosphatase is required for dephosphorylation of LjMPK6 to fine tune nodule development in L. japonicus. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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Review

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13 pages, 21296 KiB

Open AccessReview

Link between Lipid Second Messengers and Osmotic Stress in Plants

by Beatriz A. Rodas-Junco, Graciela E. Racagni-Di-Palma, Michel Canul-Chan, Javier Usorach and S. M. Teresa Hernández-Sotomayor

Int. J. Mol. Sci. 2021, 22(5), 2658; https://doi.org/10.3390/ijms22052658 - 06 Mar 2021

Cited by 17 | Viewed by 3357

Abstract

Plants are subject to different types of stress, which consequently affect their growth and development. They have developed mechanisms for recognizing and processing an extracellular signal. Second messengers are transient molecules that modulate the physiological responses in plant cells under stress conditions. In [...] Read more.

Plants are subject to different types of stress, which consequently affect their growth and development. They have developed mechanisms for recognizing and processing an extracellular signal. Second messengers are transient molecules that modulate the physiological responses in plant cells under stress conditions. In this sense, it has been shown in various plant models that membrane lipids are substrates for the generation of second lipid messengers such as phosphoinositide, phosphatidic acid, sphingolipids, and lysophospholipids. In recent years, research on lipid second messengers has been moving toward using genetic and molecular approaches to reveal the molecular setting in which these molecules act in response to osmotic stress. In this sense, these studies have established that second messengers can transiently recruit target proteins to the membrane and, therefore, affect protein conformation, activity, and gene expression. This review summarizes recent advances in responses related to the link between lipid second messengers and osmotic stress in plant cells. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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23 pages, 3237 KiB

Open AccessReview

Magnesium Signaling in Plants

by Leszek A. Kleczkowski and Abir U. Igamberdiev

Int. J. Mol. Sci. 2021, 22(3), 1159; https://doi.org/10.3390/ijms22031159 - 25 Jan 2021

Cited by 27 | Viewed by 3637

Abstract

Free magnesium (Mg²⁺) is a signal of the adenylate (ATP+ADP+AMP) status in the cells. It results from the equilibrium of adenylate kinase (AK), which uses Mg-chelated and Mg-free adenylates as substrates in both directions of its reaction. The AK-mediated primary control [...] Read more.

Free magnesium (Mg²⁺) is a signal of the adenylate (ATP+ADP+AMP) status in the cells. It results from the equilibrium of adenylate kinase (AK), which uses Mg-chelated and Mg-free adenylates as substrates in both directions of its reaction. The AK-mediated primary control of intracellular [Mg²⁺] is finely interwoven with the operation of membrane-bound adenylate- and Mg²⁺-translocators, which in a given compartment control the supply of free adenylates and Mg²⁺ for the AK-mediated equilibration. As a result, [Mg²⁺] itself varies both between and within the compartments, depending on their energetic status and environmental clues. Other key nucleotide-utilizing/producing enzymes (e.g., nucleoside diphosphate kinase) may also be involved in fine-tuning of the intracellular [Mg²⁺]. Changes in [Mg²⁺] regulate activities of myriads of Mg-utilizing/requiring enzymes, affecting metabolism under both normal and stress conditions, and impacting photosynthetic performance, respiration, phloem loading and other processes. In compartments controlled by AK equilibrium (cytosol, chloroplasts, mitochondria, nucleus), the intracellular [Mg²⁺] can be calculated from total adenylate contents, based on the dependence of the apparent equilibrium constant of AK on [Mg²⁺]. Magnesium signaling, reflecting cellular adenylate status, is likely widespread in all eukaryotic and prokaryotic organisms, due simply to the omnipresent nature of AK and to its involvement in adenylate equilibration. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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14 pages, 1529 KiB

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The Regulation of Nodule Number in Legumes Is a Balance of Three Signal Transduction Pathways

by Diptee Chaulagain and Julia Frugoli

Int. J. Mol. Sci. 2021, 22(3), 1117; https://doi.org/10.3390/ijms22031117 - 23 Jan 2021

Cited by 28 | Viewed by 4908

Abstract

Nitrogen is a major determinant of plant growth and productivity and the ability of legumes to form a symbiotic relationship with nitrogen-fixing rhizobia bacteria allows legumes to exploit nitrogen-poor niches in the biosphere. But hosting nitrogen-fixing bacteria comes with a metabolic cost, and [...] Read more.

Nitrogen is a major determinant of plant growth and productivity and the ability of legumes to form a symbiotic relationship with nitrogen-fixing rhizobia bacteria allows legumes to exploit nitrogen-poor niches in the biosphere. But hosting nitrogen-fixing bacteria comes with a metabolic cost, and the process requires regulation. The symbiosis is regulated through three signal transduction pathways: in response to available nitrogen, at the initiation of contact between the organisms, and during the development of the nodules that will host the rhizobia. Here we provide an overview of our knowledge of how the three signaling pathways operate in space and time, and what we know about the cross-talk between symbiotic signaling for nodule initiation and organogenesis, nitrate dependent signaling, and autoregulation of nodulation. Identification of common components and points of intersection suggest directions for research on the fine-tuning of the plant’s response to rhizobia. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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28 pages, 2774 KiB

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The Complex Story of Plant Cyclic Nucleotide-Gated Channels

by Edwin Jarratt-Barnham, Limin Wang, Youzheng Ning and Julia M. Davies

Int. J. Mol. Sci. 2021, 22(2), 874; https://doi.org/10.3390/ijms22020874 - 16 Jan 2021

Cited by 55 | Viewed by 6204

Abstract

Plant cyclic nucleotide-gated channels (CNGCs) are tetrameric cation channels which may be activated by the cyclic nucleotides (cNMPs) adenosine 3′,5′-cyclic monophosphate (cAMP) and guanosine 3′,5′-cyclic monophosphate (cGMP). The genome of Arabidopsis thaliana encodes 20 CNGC subunits associated with aspects of development, stress response [...] Read more.

Plant cyclic nucleotide-gated channels (CNGCs) are tetrameric cation channels which may be activated by the cyclic nucleotides (cNMPs) adenosine 3′,5′-cyclic monophosphate (cAMP) and guanosine 3′,5′-cyclic monophosphate (cGMP). The genome of Arabidopsis thaliana encodes 20 CNGC subunits associated with aspects of development, stress response and immunity. Recently, it has been demonstrated that CNGC subunits form heterotetrameric complexes which behave differently from the homotetramers produced by their constituent subunits. These findings have widespread implications for future signalling research and may help explain how specificity can be achieved by CNGCs that are known to act in disparate pathways. Regulation of complex formation may involve cyclic nucleotide-gated channel-like proteins. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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12 pages, 1405 KiB

Open AccessReview

Signal Integration by Cyclin-Dependent Kinase 8 (CDK8) Module and Other Mediator Subunits in Biotic and Abiotic Stress Responses

by Leelyn Chong, Xiaoning Shi and Yingfang Zhu

Int. J. Mol. Sci. 2021, 22(1), 354; https://doi.org/10.3390/ijms22010354 - 31 Dec 2020

Cited by 11 | Viewed by 2854

Abstract

Environmental stresses have driven plants to develop various mechanisms to acclimate in adverse conditions. Extensive studies have demonstrated that a significant reprogramming occurs in the plant transcriptome in response to biotic and abiotic stresses. The highly conserved and large multi-subunit transcriptional co-activator of [...] Read more.

Environmental stresses have driven plants to develop various mechanisms to acclimate in adverse conditions. Extensive studies have demonstrated that a significant reprogramming occurs in the plant transcriptome in response to biotic and abiotic stresses. The highly conserved and large multi-subunit transcriptional co-activator of eukaryotes, known as the Mediator, has been reported to play a substantial role in the regulation of important genes that help plants respond to environmental perturbances. CDK8 module is a relatively new component of the Mediator complex that has been shown to contribute to plants’ defense, development, and stress responses. Previous studies reported that CDK8 module predominantly acts as a transcriptional repressor in eukaryotic cells by reversibly associating with core Mediator. However, growing evidence has demonstrated that depending on the type of biotic and abiotic stress, the CDK8 module may perform a contrasting regulatory role. This review will summarize the current knowledge of CDK8 module as well as other previously documented Mediator subunits in plant cell signaling under stress conditions. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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12 pages, 627 KiB

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ROS and Ions in Cell Signaling during Sexual Plant Reproduction

by Maria Breygina and Ekaterina Klimenko

Int. J. Mol. Sci. 2020, 21(24), 9476; https://doi.org/10.3390/ijms21249476 - 13 Dec 2020

Cited by 19 | Viewed by 3221

Abstract

Pollen grain is a unique haploid organism characterized by two key physiological processes: activation of metabolism upon exiting dormancy and polar tube growth. In gymnosperms and flowering plants, these processes occur in different time frames and exhibit important features; identification of similarities and [...] Read more.

Pollen grain is a unique haploid organism characterized by two key physiological processes: activation of metabolism upon exiting dormancy and polar tube growth. In gymnosperms and flowering plants, these processes occur in different time frames and exhibit important features; identification of similarities and differences is still in the active phase. In angiosperms, the growth of male gametophyte is directed and controlled by its microenvironment, while in gymnosperms it is relatively autonomous. Recent reviews have detailed aspects of interaction between angiosperm female tissues and pollen such as interactions between peptides and their receptors; however, accumulated evidence suggests low-molecular communication, in particular, through ion exchange and ROS production, equally important for polar growth as well as for pollen germination. Recently, it became clear that ROS and ionic currents form a single regulatory module, since ROS production and the activity of ion transport systems are closely interrelated and form a feedback loop. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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27 pages, 3360 KiB

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The Effect of Virulence and Resistance Mechanisms on the Interactions between Parasitic Plants and Their Hosts

by Luyang Hu, Jiansu Wang, Chong Yang, Faisal Islam, Harro J. Bouwmeester, Stéphane Muños and Weijun Zhou

Int. J. Mol. Sci. 2020, 21(23), 9013; https://doi.org/10.3390/ijms21239013 - 27 Nov 2020

Cited by 17 | Viewed by 4166

Abstract

Parasitic plants have a unique heterotrophic lifestyle based on the extraction of water and nutrients from host plants. Some parasitic plant species, particularly those of the family Orobanchaceae, attack crops and cause substantial yield losses. The breeding of resistant crop varieties is an [...] Read more.

Parasitic plants have a unique heterotrophic lifestyle based on the extraction of water and nutrients from host plants. Some parasitic plant species, particularly those of the family Orobanchaceae, attack crops and cause substantial yield losses. The breeding of resistant crop varieties is an inexpensive way to control parasitic weeds, but often does not provide a long-lasting solution because the parasites rapidly evolve to overcome resistance. Understanding mechanisms underlying naturally occurring parasitic plant resistance is of great interest and could help to develop methods to control parasitic plants. In this review, we describe the virulence mechanisms of parasitic plants and resistance mechanisms in their hosts, focusing on obligate root parasites of the genera Orobanche and Striga. We noticed that the resistance (R) genes in the host genome often encode proteins with nucleotide-binding and leucine-rich repeat domains (NLR proteins), hence we proposed a mechanism by which host plants use NLR proteins to activate downstream resistance gene expression. We speculated how parasitic plants and their hosts co-evolved and discussed what drives the evolution of virulence effectors in parasitic plants by considering concepts from similar studies of plant–microbe interaction. Most previous studies have focused on the host rather than the parasite, so we also provided an updated summary of genomic resources for parasitic plants and parasitic genes for further research to test our hypotheses. Finally, we discussed new approaches such as CRISPR/Cas9-mediated genome editing and RNAi silencing that can provide deeper insight into the intriguing life cycle of parasitic plants and could potentially contribute to the development of novel strategies for controlling parasitic weeds, thereby enhancing crop productivity and food security globally. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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24 pages, 1864 KiB

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Retrograde Signaling: Understanding the Communication between Organelles

by Jakub Mielecki, Piotr Gawroński and Stanisław Karpiński

Int. J. Mol. Sci. 2020, 21(17), 6173; https://doi.org/10.3390/ijms21176173 - 26 Aug 2020

Cited by 37 | Viewed by 7236

Abstract

Understanding how cell organelles and compartments communicate with each other has always been an important field of knowledge widely explored by many researchers. However, despite years of investigations, one point—and perhaps the only point that many agree on—is that our knowledge about cellular-signaling [...] Read more.

Understanding how cell organelles and compartments communicate with each other has always been an important field of knowledge widely explored by many researchers. However, despite years of investigations, one point—and perhaps the only point that many agree on—is that our knowledge about cellular-signaling pathways still requires expanding. Chloroplasts and mitochondria (because of their primary functions in energy conversion) are important cellular sensors of environmental fluctuations and feedback they provide back to the nucleus is important for acclimatory responses. Under stressful conditions, it is important to manage cellular resources more efficiently in order to maintain a proper balance between development, growth and stress responses. For example, it can be achieved through regulation of nuclear and organellar gene expression. If plants are unable to adapt to stressful conditions, they will be unable to efficiently produce energy for growth and development—and ultimately die. In this review, we show the importance of retrograde signaling in stress responses, including the induction of cell death and in organelle biogenesis. The complexity of these pathways demonstrates how challenging it is to expand the existing knowledge. However, understanding this sophisticated communication may be important to develop new strategies of how to improve adaptability of plants in rapidly changing environments. Full article

(This article belongs to the Special Issue Cell Signaling in Model Plants 2.0)

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