{"title":"Loading the Centromere during Embryogenesis: NASP Functions in de Novo CENH3 Deposition.","authors":"Matthew Naish, Ian R Henderson","doi":"10.1093/pcp/pcae068","DOIUrl":"10.1093/pcp/pcae068","url":null,"abstract":"","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141559485","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alwine Wilkens, Paweł Czerniawski, Paweł Bednarek, Marta Libik-Konieczny, Kenji Yamada
Endoplasmic reticulum (ER)-derived organelles, ER bodies, participate in the defense against herbivores in Brassicaceae plants. ER bodies accumulate β-glucosidases, which hydrolyze specialized thioglucosides known as glucosinolates to generate bioactive substances. In Arabidopsis thaliana, the leaf ER (LER) bodies are formed in large pavement cells, which are found in the petioles, margins and blades of rosette leaves. However, the regulatory mechanisms involved in establishing large pavement cells are unknown. Here, we show that the ARABIDOPSIS THALIANA MERISTEM L1 LAYER (ATML1) transcription factor regulates the formation of LER bodies in large pavement cells of rosette leaves. Overexpression of ATML1 enhanced the expression of LER body-related genes and the number of LER body-containing large pavement cells, whereas its knock-out resulted in opposite effects. ATML1 enhances endoreduplication and cell size through LOSS OF GIANT CELLS FROM ORGANS (LGO). Although the overexpression and knock-out of LGO affected the appearance of large pavement cells in Arabidopsis, the effect on LER body-related gene expression and LER body formation was weak. LER body-containing large pavement cells were also found in Eutrema salsugineum, another Brassicaceae species. Our results demonstrate that ATML1 establishes large pavement cells to induce LER body formation in Brassicaceae plants and thereby possibly contribute to the defense against herbivores.
{"title":"ATML1 Regulates the Differentiation of ER Body-Containing Large Pavement Cells in Rosette Leaves of Brassicaceae Plants.","authors":"Alwine Wilkens, Paweł Czerniawski, Paweł Bednarek, Marta Libik-Konieczny, Kenji Yamada","doi":"10.1093/pcp/pcae039","DOIUrl":"10.1093/pcp/pcae039","url":null,"abstract":"<p><p>Endoplasmic reticulum (ER)-derived organelles, ER bodies, participate in the defense against herbivores in Brassicaceae plants. ER bodies accumulate β-glucosidases, which hydrolyze specialized thioglucosides known as glucosinolates to generate bioactive substances. In Arabidopsis thaliana, the leaf ER (LER) bodies are formed in large pavement cells, which are found in the petioles, margins and blades of rosette leaves. However, the regulatory mechanisms involved in establishing large pavement cells are unknown. Here, we show that the ARABIDOPSIS THALIANA MERISTEM L1 LAYER (ATML1) transcription factor regulates the formation of LER bodies in large pavement cells of rosette leaves. Overexpression of ATML1 enhanced the expression of LER body-related genes and the number of LER body-containing large pavement cells, whereas its knock-out resulted in opposite effects. ATML1 enhances endoreduplication and cell size through LOSS OF GIANT CELLS FROM ORGANS (LGO). Although the overexpression and knock-out of LGO affected the appearance of large pavement cells in Arabidopsis, the effect on LER body-related gene expression and LER body formation was weak. LER body-containing large pavement cells were also found in Eutrema salsugineum, another Brassicaceae species. Our results demonstrate that ATML1 establishes large pavement cells to induce LER body formation in Brassicaceae plants and thereby possibly contribute to the defense against herbivores.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11287205/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140864756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anoxygenic photosynthesis is diversified into two classes: chlorophototrophy based on a bacterial type-I or type-II reaction center (RC). Whereas the type-I RC contains both bacteriochlorophyll and chlorophyll, type-II RC-based phototrophy relies only on bacteriochlorophyll. However, type-II phototrophic bacteria theoretically have the potential to produce chlorophyll a by the addition of an enzyme, chlorophyll synthase, because the direct precursor for the enzyme, chlorophyllide a, is produced as an intermediate of BChl a biosynthesis. In this study, we attempted to modify the type-II proteobacterial phototroph Rhodovulum sulfidophilum to produce chlorophyll a by introducing chlorophyll synthase, which catalyzes the esterification of a diterpenoid group to chlorophyllide a thereby producing chlorophyll a. However, the resulting strain did not accumulate chlorophyll a, perhaps due to absence of endogenous chlorophyll a-binding proteins. We further heterologously incorporated genes encoding the type-I RC complex to provide a target for chlorophyll a. Heterologous expression of type-I RC subunits, chlorophyll synthase, and galactolipid synthase successfully afforded detectable accumulation of chlorophyll a in Rdv. sulfidophilum. This suggests that the type-I RC can work to accumulate chlorophyll a and that galactolipids are likely necessary for the type-I RC assembly. The evolutionary acquisition of type-I RCs could be related to prior or concomitant acquisition of galactolipids and chlorophylls.
缺氧光合作用分为两类:基于细菌 I 型或 II 型反应中心(RC)的光营养作用。I 型 RC 同时含有细菌叶绿素和叶绿素,而基于 II 型 RC 的光营养只依赖于细菌叶绿素。然而,理论上 II 型光养细菌有可能通过添加叶绿素合成酶来产生叶绿素 a,因为叶绿素合成酶的直接前体叶绿素化物 a 是 BChl a 生物合成的中间产物。在本研究中,我们尝试通过引入叶绿素合成酶来改造 II 型蛋白细菌光营养体 Rhodovulum sulfidophilum,使其产生叶绿素 a,叶绿素合成酶可催化二萜类基团与叶绿素 a 的酯化反应,从而产生叶绿素 a。我们进一步异源整合了编码 I 型 RC 复合物的基因,以提供叶绿素 a 的靶标。异源表达 I 型 RC 亚基、叶绿素合成酶和半乳糖脂合成酶,成功地在 Rdv. sulfidophilum 中积累了可检测到的叶绿素 a。这表明,I型RC可以积累叶绿素a,而半乳糖脂可能是I型RC组装所必需的。I 型 RC 的进化获得可能与事先或同时获得半乳糖脂和叶绿素有关。
{"title":"Genes for the type-I reaction center and galactolipid synthesis are required for chlorophyll a accumulation in a purple photosynthetic bacterium.","authors":"Yusuke Tsukatani, Chihiro Azai, Tomoyasu Noji, Shigeru Kawai, Saori Sugimoto, Shigeru Shimamura, Yasuhiro Shimane, Jiro Harada, Tadashi Mizoguchi, Hitoshi Tamiaki, Shinji Masuda","doi":"10.1093/pcp/pcae076","DOIUrl":"https://doi.org/10.1093/pcp/pcae076","url":null,"abstract":"<p><p>Anoxygenic photosynthesis is diversified into two classes: chlorophototrophy based on a bacterial type-I or type-II reaction center (RC). Whereas the type-I RC contains both bacteriochlorophyll and chlorophyll, type-II RC-based phototrophy relies only on bacteriochlorophyll. However, type-II phototrophic bacteria theoretically have the potential to produce chlorophyll a by the addition of an enzyme, chlorophyll synthase, because the direct precursor for the enzyme, chlorophyllide a, is produced as an intermediate of BChl a biosynthesis. In this study, we attempted to modify the type-II proteobacterial phototroph Rhodovulum sulfidophilum to produce chlorophyll a by introducing chlorophyll synthase, which catalyzes the esterification of a diterpenoid group to chlorophyllide a thereby producing chlorophyll a. However, the resulting strain did not accumulate chlorophyll a, perhaps due to absence of endogenous chlorophyll a-binding proteins. We further heterologously incorporated genes encoding the type-I RC complex to provide a target for chlorophyll a. Heterologous expression of type-I RC subunits, chlorophyll synthase, and galactolipid synthase successfully afforded detectable accumulation of chlorophyll a in Rdv. sulfidophilum. This suggests that the type-I RC can work to accumulate chlorophyll a and that galactolipids are likely necessary for the type-I RC assembly. The evolutionary acquisition of type-I RCs could be related to prior or concomitant acquisition of galactolipids and chlorophylls.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141727685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pieter Clauw, Thomas James Ellis, Hai-Jun Liu, Eriko Sasaki
Classic genome-wide association studies (GWAS) look for associations between individual SNPs and phenotypes of interest. With the rapid progress of high-throughput genotyping and phenotyping technologies, GWAS have become increasingly powerful for detecting genetic determinants and their molecular mechanisms underpinning natural phenotypic variation. However, GWAS frequently yield results with neither expected nor promising loci, nor any significant associations. This is often because associations between SNPs and a single phenotype are confounded, for example with the environment, other traits, or complex genetic structures. Such confounding can mask true genotype-phenotype associations, or inflate spurious associations. To address these problems, numerous methods have been developed that go beyond the standard model. Such advanced GWAS models are flexible and can offer improved statistical power for understanding the genetics underlying complex traits. Despite this advantage, these models have not been widely adopted and implemented compared to the standard GWAS approach, partly because this literature is diverse and often technical. In this review, our aim is to provide an overview of the application and the benefits of various advanced GWAS models for handling complex traits and genetic structures, targeting plant biologists who wish to carry out GWAS more effectively.
经典的全基因组关联研究(GWAS)寻找单个 SNP 与相关表型之间的关联。随着高通量基因分型和表型技术的快速发展,全基因组关联研究在检测遗传决定因素及其支撑自然表型变异的分子机制方面变得越来越强大。然而,GWAS 的结果往往既没有预期的基因位点,也没有有希望的基因位点,更没有任何显著的关联。这往往是因为 SNP 与单一表型之间的关联受到了干扰,例如与环境、其他性状或复杂遗传结构之间的干扰。这种混杂会掩盖基因型与表型之间的真实关联,或夸大虚假关联。为了解决这些问题,人们开发了许多超越标准模型的方法。这些先进的 GWAS 模型非常灵活,能为了解复杂性状的遗传学基础提供更好的统计能力。尽管有这样的优势,但与标准 GWAS 方法相比,这些模型还没有被广泛采用和实施,部分原因是这些文献多种多样,而且往往是技术性的。在这篇综述中,我们的目的是概述各种先进 GWAS 模型在处理复杂性状和遗传结构方面的应用和优势,以希望更有效地开展 GWAS 的植物生物学家为目标。
{"title":"Beyond the standard GWAS - a guide for plant biologists.","authors":"Pieter Clauw, Thomas James Ellis, Hai-Jun Liu, Eriko Sasaki","doi":"10.1093/pcp/pcae079","DOIUrl":"https://doi.org/10.1093/pcp/pcae079","url":null,"abstract":"<p><p>Classic genome-wide association studies (GWAS) look for associations between individual SNPs and phenotypes of interest. With the rapid progress of high-throughput genotyping and phenotyping technologies, GWAS have become increasingly powerful for detecting genetic determinants and their molecular mechanisms underpinning natural phenotypic variation. However, GWAS frequently yield results with neither expected nor promising loci, nor any significant associations. This is often because associations between SNPs and a single phenotype are confounded, for example with the environment, other traits, or complex genetic structures. Such confounding can mask true genotype-phenotype associations, or inflate spurious associations. To address these problems, numerous methods have been developed that go beyond the standard model. Such advanced GWAS models are flexible and can offer improved statistical power for understanding the genetics underlying complex traits. Despite this advantage, these models have not been widely adopted and implemented compared to the standard GWAS approach, partly because this literature is diverse and often technical. In this review, our aim is to provide an overview of the application and the benefits of various advanced GWAS models for handling complex traits and genetic structures, targeting plant biologists who wish to carry out GWAS more effectively.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141580649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mana Fukazawa, Keita Miyake, Hiroki Hoshino, Keiji Fushimi, Rei Narikawa
A novel photoreceptor dualchrome 1 (DUC1), containing a fused structure of cryptochrome and phytochrome, was discovered in the marine green alga Pycnococcus provasolli. The DUC1 phytochrome region (PpDUC1-N) binds to the bilin (linear tetrapyrrole) chromophores, phytochromobilin (PΦB) or phycocyanobilin (PCB), and reversibly photoconverts between the orange-absorbing dark-adapted state and the far-red-absorbing photoproduct state. This contrasts with typical phytochromes, which photoconvert between the red-absorbing dark-adapted and far-red-absorbing photoproduct states. In this study, we examined the molecular mechanism of PpDUC1-N to sense orange light by identifying the chromophore species synthesized by P. provasolli and the amino acid residues within the PpDUC1-N responsible for sensing orange light in the dark-adapted state. We focused on the PcyA homolog of P. provasolli (PpPcyA). Coexpression with the photoreceptors followed by an enzymatic assay revealed that PpPcyA synthesized PCB. Next, we focused on the PpDUC1-N GAF domain responsible for chromophore binding and light sensing. Ten amino acid residues were selected as the mutagenesis target near the chromophore. Replacement of these residues with those conserved in typical phytochromes revealed that three mutations (F290Y/M304S/L353M) resulted in a 23-nm red-shift in the dark-adapted state. Finally, we combined these constructs to obtain the PΦB-binding F290Y/M304S/L353M mutant and a 38-nm red-shift was observed compared with the PCB-binding wild-type PpDUC1. The binding chromophore species and the key residues near the chromophore contribute to blue-shifted orange light sensing in the dark-adapted state of the PpDUC1-N.
{"title":"Phytochromobilin Binding and Specific Amino Acid Residues Near The Chromophore Contribute To Orange Light Perception By The Dualchrome Phytochrome Region.","authors":"Mana Fukazawa, Keita Miyake, Hiroki Hoshino, Keiji Fushimi, Rei Narikawa","doi":"10.1093/pcp/pcae077","DOIUrl":"https://doi.org/10.1093/pcp/pcae077","url":null,"abstract":"<p><p>A novel photoreceptor dualchrome 1 (DUC1), containing a fused structure of cryptochrome and phytochrome, was discovered in the marine green alga Pycnococcus provasolli. The DUC1 phytochrome region (PpDUC1-N) binds to the bilin (linear tetrapyrrole) chromophores, phytochromobilin (PΦB) or phycocyanobilin (PCB), and reversibly photoconverts between the orange-absorbing dark-adapted state and the far-red-absorbing photoproduct state. This contrasts with typical phytochromes, which photoconvert between the red-absorbing dark-adapted and far-red-absorbing photoproduct states. In this study, we examined the molecular mechanism of PpDUC1-N to sense orange light by identifying the chromophore species synthesized by P. provasolli and the amino acid residues within the PpDUC1-N responsible for sensing orange light in the dark-adapted state. We focused on the PcyA homolog of P. provasolli (PpPcyA). Coexpression with the photoreceptors followed by an enzymatic assay revealed that PpPcyA synthesized PCB. Next, we focused on the PpDUC1-N GAF domain responsible for chromophore binding and light sensing. Ten amino acid residues were selected as the mutagenesis target near the chromophore. Replacement of these residues with those conserved in typical phytochromes revealed that three mutations (F290Y/M304S/L353M) resulted in a 23-nm red-shift in the dark-adapted state. Finally, we combined these constructs to obtain the PΦB-binding F290Y/M304S/L353M mutant and a 38-nm red-shift was observed compared with the PCB-binding wild-type PpDUC1. The binding chromophore species and the key residues near the chromophore contribute to blue-shifted orange light sensing in the dark-adapted state of the PpDUC1-N.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141580651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wan-Ting Mao, Wei-Han Hsu, Jia-Lin Song, Chang-Hsien Yang
To analyze the gene involved in orchid floral development, a HD-Zip II gene PaHAT14, which specifically and highly expressed in perianth during early flower development was identified from Phalaenopsis. Transgenic Arabidopsis plants expressing 35S::PaHAT14 and 35S::PaHAT14+SRDX (fused with the repressor motif SRDX) exhibited similar altered phenotypes, including small leaves, early flowering, and bending petals with increased cuticle production. This suggests that PaHAT14 acts as a repressor. In contrast, transgenic Arabidopsis plants expressing 35S::PaHAT14+VP16 (fused with the activation domain VP16) exhibited curled leaves, late flowering, and folded petals with decreased cuticle production within hardly opened flowers. Additionally, the expression of the ERF gene DEWAX2, which negatively regulates cuticular wax biosynthesis, was down-regulated in 35S::PaHAT14 and 35S::PaHAT14+SRDX transgenic Arabidopsis, while it was up-regulated in 35S::PaHAT14+VP16 transgenic Arabidopsis. Furthermore, transient overexpression of PaHAT14 in Phalaenopsis petal/sepal increased cuticle deposition due to the down-regulation of PaERF105, a Phalaenopsis DEWAX2 orthologue. On the other hand, transient overexpression of PaERF105 decreased cuticle deposition, whereas cuticle deposition increased and the rate of epidermal water loss was reduced in PaERF105 VIGS Phalaenopsis flowers. Moreover, ectopic expression of PaERF105 not only produced phenotypes similar to those in 35S::PaHAT14+VP16 Arabidopsis but also compensated for the altered phenotypes observed in 35S::PaHAT14 and 35S::PaHAT14+SRDX Arabidopsis. These results suggest that PaHAT14 promotes cuticle deposition by negatively regulating downstream gene PaERF105 in orchid flowers.
{"title":"The HD-ZIP II gene PaHAT14 increases cuticle deposition by down-regulating ERF gene PaERF105 in Phalaenopsis.","authors":"Wan-Ting Mao, Wei-Han Hsu, Jia-Lin Song, Chang-Hsien Yang","doi":"10.1093/pcp/pcae078","DOIUrl":"https://doi.org/10.1093/pcp/pcae078","url":null,"abstract":"<p><p>To analyze the gene involved in orchid floral development, a HD-Zip II gene PaHAT14, which specifically and highly expressed in perianth during early flower development was identified from Phalaenopsis. Transgenic Arabidopsis plants expressing 35S::PaHAT14 and 35S::PaHAT14+SRDX (fused with the repressor motif SRDX) exhibited similar altered phenotypes, including small leaves, early flowering, and bending petals with increased cuticle production. This suggests that PaHAT14 acts as a repressor. In contrast, transgenic Arabidopsis plants expressing 35S::PaHAT14+VP16 (fused with the activation domain VP16) exhibited curled leaves, late flowering, and folded petals with decreased cuticle production within hardly opened flowers. Additionally, the expression of the ERF gene DEWAX2, which negatively regulates cuticular wax biosynthesis, was down-regulated in 35S::PaHAT14 and 35S::PaHAT14+SRDX transgenic Arabidopsis, while it was up-regulated in 35S::PaHAT14+VP16 transgenic Arabidopsis. Furthermore, transient overexpression of PaHAT14 in Phalaenopsis petal/sepal increased cuticle deposition due to the down-regulation of PaERF105, a Phalaenopsis DEWAX2 orthologue. On the other hand, transient overexpression of PaERF105 decreased cuticle deposition, whereas cuticle deposition increased and the rate of epidermal water loss was reduced in PaERF105 VIGS Phalaenopsis flowers. Moreover, ectopic expression of PaERF105 not only produced phenotypes similar to those in 35S::PaHAT14+VP16 Arabidopsis but also compensated for the altered phenotypes observed in 35S::PaHAT14 and 35S::PaHAT14+SRDX Arabidopsis. These results suggest that PaHAT14 promotes cuticle deposition by negatively regulating downstream gene PaERF105 in orchid flowers.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141580666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sujeong Je, Bae Young Choi, Eunbi Kim, Kyungyoon Kim, Yuree Lee, Yasuyo Yamaoka
The endoplasmic reticulum (ER) stress response is an evolutionarily conserved mechanism in most eukaryotes. In this response, sterols in the phospholipid bilayer play a crucial role in controlling membrane fluidity and homeostasis. Despite the significance of both the ER stress response and sterols in maintaining ER homeostasis, their relationship remains poorly explored. Our investigation focused on Chlamydomonas strain CC-4533 and revealed that free sterol biosynthesis increased in response to ER stress, except in mutants of the ER stress sensor Inositol-requiring enzyme 1 (IRE1). Transcript analysis of Chlamydomonas experiencing ER stress unveiled the regulatory role of the IRE1/basic leucine zipper 1 pathway in inducing the expression of ERG5, which encodes C-22 sterol desaturase. Through the isolation of three erg5 mutant alleles, we observed a defect in the synthesis of Chlamydomonas' sterol end products, ergosterol and 7-dehydroporiferasterol. Furthermore, these erg5 mutants also exhibited increased sensitivity to ER stress induced by brefeldin A (BFA, an inhibitor of ER-Golgi trafficking), whereas tunicamycin (an inhibitor of N-glycosylation) and dithiothreitol (an inhibitor of disulfide-bond formation) had no such effect. Intriguingly, the sterol biosynthesis inhibitors fenpropimorph and fenhexamid, which impede steps upstream of the ERG5 enzyme in sterol biosynthesis, rescued BFA hypersensitivity in CC-4533 cells. Collectively, our findings support the conclusion that the accumulation of intermediates in the sterol biosynthetic pathway influences ER stress in a complex manner. This study highlights the significance and complexity of regulating sterol biosynthesis during the ER stress response in microalgae.
{"title":"Sterol Biosynthesis Contributes to Brefeldin-A-Induced Endoplasmic Reticulum Stress Resistance in Chlamydomonas reinhardtii.","authors":"Sujeong Je, Bae Young Choi, Eunbi Kim, Kyungyoon Kim, Yuree Lee, Yasuyo Yamaoka","doi":"10.1093/pcp/pcad131","DOIUrl":"10.1093/pcp/pcad131","url":null,"abstract":"<p><p>The endoplasmic reticulum (ER) stress response is an evolutionarily conserved mechanism in most eukaryotes. In this response, sterols in the phospholipid bilayer play a crucial role in controlling membrane fluidity and homeostasis. Despite the significance of both the ER stress response and sterols in maintaining ER homeostasis, their relationship remains poorly explored. Our investigation focused on Chlamydomonas strain CC-4533 and revealed that free sterol biosynthesis increased in response to ER stress, except in mutants of the ER stress sensor Inositol-requiring enzyme 1 (IRE1). Transcript analysis of Chlamydomonas experiencing ER stress unveiled the regulatory role of the IRE1/basic leucine zipper 1 pathway in inducing the expression of ERG5, which encodes C-22 sterol desaturase. Through the isolation of three erg5 mutant alleles, we observed a defect in the synthesis of Chlamydomonas' sterol end products, ergosterol and 7-dehydroporiferasterol. Furthermore, these erg5 mutants also exhibited increased sensitivity to ER stress induced by brefeldin A (BFA, an inhibitor of ER-Golgi trafficking), whereas tunicamycin (an inhibitor of N-glycosylation) and dithiothreitol (an inhibitor of disulfide-bond formation) had no such effect. Intriguingly, the sterol biosynthesis inhibitors fenpropimorph and fenhexamid, which impede steps upstream of the ERG5 enzyme in sterol biosynthesis, rescued BFA hypersensitivity in CC-4533 cells. Collectively, our findings support the conclusion that the accumulation of intermediates in the sterol biosynthetic pathway influences ER stress in a complex manner. This study highlights the significance and complexity of regulating sterol biosynthesis during the ER stress response in microalgae.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49681601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kazuma Uesaka, Mari Banba, Sotaro Chiba, Yuichi Fujita
In the genome of the heterocystous cyanobacterium Calothrix sp. NIES-4101 (NIES-4101), the four genes essential for nitrogen fixation (nifB, nifH, nifD and nifK) are highly fragmented into 13 parts in a 350-kb chromosomal region, and four of these parts are encoded in the reverse strand. Such a complex fragmentation feature makes it difficult to restore the intact nifBHDK genes by the excision mechanism found in the nifD gene of the Anabaena sp. PCC 7120 heterocyst. To examine the nitrogen-fixing ability of NIES-4101, we confirmed that NIES-4101 grew well on a combined nitrogen-free medium and showed high nitrogenase activity, which strongly suggested that the complete nifBHDK genes are restored by a complex recombination process in heterocysts. Next, we resequenced the genome prepared from cells grown under nitrogen-fixing conditions. Two contigs covering the complete nifHDK and nifB genes were found by de novo assembly of the sequencing reads. In addition, the DNA fragments covering the nifBHDK operon were successfully amplified by PCR. We propose that the process of nifBHDK restoration occurs as follows. First, the nifD-nifK genes are restored by four excision events. Then, the complete nifH and nifB genes are restored by two excision events followed by two successive inversion events between the inverted repeat sequences and one excision event, forming the functional nif gene cluster, nifB-fdxN-nifS-nifU-nifH-nifD-nifK. All genes coding recombinases responsible for these nine recombination events are located close to the terminal repeat sequences. The restoration of the nifBHDK genes in NIES-4101 is the most complex genome reorganization reported in heterocystous cyanobacteria.
{"title":"Restoration of the Functional nif Gene Cluster by Complex Recombination Events during Heterocyst Development in the Nitrogen-Fixing Cyanobacterium Calothrix sp. NIES-4101.","authors":"Kazuma Uesaka, Mari Banba, Sotaro Chiba, Yuichi Fujita","doi":"10.1093/pcp/pcae011","DOIUrl":"10.1093/pcp/pcae011","url":null,"abstract":"<p><p>In the genome of the heterocystous cyanobacterium Calothrix sp. NIES-4101 (NIES-4101), the four genes essential for nitrogen fixation (nifB, nifH, nifD and nifK) are highly fragmented into 13 parts in a 350-kb chromosomal region, and four of these parts are encoded in the reverse strand. Such a complex fragmentation feature makes it difficult to restore the intact nifBHDK genes by the excision mechanism found in the nifD gene of the Anabaena sp. PCC 7120 heterocyst. To examine the nitrogen-fixing ability of NIES-4101, we confirmed that NIES-4101 grew well on a combined nitrogen-free medium and showed high nitrogenase activity, which strongly suggested that the complete nifBHDK genes are restored by a complex recombination process in heterocysts. Next, we resequenced the genome prepared from cells grown under nitrogen-fixing conditions. Two contigs covering the complete nifHDK and nifB genes were found by de novo assembly of the sequencing reads. In addition, the DNA fragments covering the nifBHDK operon were successfully amplified by PCR. We propose that the process of nifBHDK restoration occurs as follows. First, the nifD-nifK genes are restored by four excision events. Then, the complete nifH and nifB genes are restored by two excision events followed by two successive inversion events between the inverted repeat sequences and one excision event, forming the functional nif gene cluster, nifB-fdxN-nifS-nifU-nifH-nifD-nifK. All genes coding recombinases responsible for these nine recombination events are located close to the terminal repeat sequences. The restoration of the nifBHDK genes in NIES-4101 is the most complex genome reorganization reported in heterocystous cyanobacteria.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11249958/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139672528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ruiqin Zhong, Dennis R Phillips, Kevin D Clark, Earle R Adams, Chanhui Lee, Zheng-Hua Ye
Grass xylan consists of a linear chain of β-1,4-linked xylosyl residues that often form domains substituted only with either arabinofuranose (Araf) or glucuronic acid (GlcA)/methylglucuronic acid (MeGlcA) residues, and it lacks the unique reducing end tetrasaccharide sequence found in dicot xylan. The mechanism of how grass xylan backbone elongation is initiated and how its distinctive substitution pattern is determined remains elusive. Here, we performed biochemical characterization of rice xylan biosynthetic enzymes, including xylan synthases, glucuronyltransferases and methyltransferases. Activity assays of rice xylan synthases demonstrated that they required short xylooligomers as acceptors for their activities. While rice xylan glucuronyltransferases effectively glucuronidated unsubstituted xylohexaose acceptors, they transferred little GlcA residues onto (Araf)-substituted xylohexaoses and rice xylan 3-O-arabinosyltransferase could not arabinosylate GlcA-substituted xylohexaoses, indicating that their intrinsic biochemical properties may contribute to the distinctive substitution patterns of rice xylan. In addition, we found that rice xylan methyltransferase exhibited a low substrate binding affinity, which may explain the partial GlcA methylation in rice xylan. Furthermore, immunolocalization of xylan in xylem cells of both rice and Arabidopsis showed that it was deposited together with cellulose in secondary walls without forming xylan-rich nanodomains. Together, our findings provide new insights into the biochemical mechanisms underlying xylan backbone elongation and substitutions in grass species.
{"title":"Biochemical Characterization of Rice Xylan Biosynthetic Enzymes in Determining Xylan Chain Elongation and Substitutions.","authors":"Ruiqin Zhong, Dennis R Phillips, Kevin D Clark, Earle R Adams, Chanhui Lee, Zheng-Hua Ye","doi":"10.1093/pcp/pcae028","DOIUrl":"10.1093/pcp/pcae028","url":null,"abstract":"<p><p>Grass xylan consists of a linear chain of β-1,4-linked xylosyl residues that often form domains substituted only with either arabinofuranose (Araf) or glucuronic acid (GlcA)/methylglucuronic acid (MeGlcA) residues, and it lacks the unique reducing end tetrasaccharide sequence found in dicot xylan. The mechanism of how grass xylan backbone elongation is initiated and how its distinctive substitution pattern is determined remains elusive. Here, we performed biochemical characterization of rice xylan biosynthetic enzymes, including xylan synthases, glucuronyltransferases and methyltransferases. Activity assays of rice xylan synthases demonstrated that they required short xylooligomers as acceptors for their activities. While rice xylan glucuronyltransferases effectively glucuronidated unsubstituted xylohexaose acceptors, they transferred little GlcA residues onto (Araf)-substituted xylohexaoses and rice xylan 3-O-arabinosyltransferase could not arabinosylate GlcA-substituted xylohexaoses, indicating that their intrinsic biochemical properties may contribute to the distinctive substitution patterns of rice xylan. In addition, we found that rice xylan methyltransferase exhibited a low substrate binding affinity, which may explain the partial GlcA methylation in rice xylan. Furthermore, immunolocalization of xylan in xylem cells of both rice and Arabidopsis showed that it was deposited together with cellulose in secondary walls without forming xylan-rich nanodomains. Together, our findings provide new insights into the biochemical mechanisms underlying xylan backbone elongation and substitutions in grass species.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140158809","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Max van Hooren, Ringo van Wijk, Irina I Vaseva, Dominique Van Der Straeten, Michel Haring, Teun Munnik
Phospholipase C (PLC) has been implicated in several stress responses, including drought. Overexpression (OE) of PLC has been shown to improve drought tolerance in various plant species. Arabidopsis contains nine PLC genes, which are subdivided into four clades. Earlier, OE of PLC3, PLC5 or PLC7 was found to increase Arabidopsis' drought tolerance. Here, we confirm this for three other PLCs: PLC2, the only constitutively expressed AtPLC; PLC4, reported to have reduced salt tolerance and PLC9, of which the encoded enzyme was presumed to be catalytically inactive. To compare each PLC and to discover any other potential phenotype, two independent OE lines of six AtPLC genes, representing all four clades, were simultaneously monitored with the GROWSCREEN-FLUORO phenotyping platform, under both control- and mild-drought conditions. To investigate which tissues were most relevant to achieving drought survival, we additionally expressed AtPLC5 using 13 different cell- or tissue-specific promoters. While no significant differences in plant size, biomass or photosynthesis were found between PLC lines and wild-type (WT) plants, all PLC-OE lines, as well as those tissue-specific lines that promoted drought survival, exhibited a stronger decrease in 'convex hull perimeter' (= increase in 'compactness') under water deprivation compared to WT. Increased compactness has not been associated with drought or decreased water loss before although a hyponastic decrease in compactness in response to increased temperatures has been associated with water loss. We propose that the increased compactness could lead to decreased water loss and potentially provide a new breeding trait to select for drought tolerance.
{"title":"Ectopic Expression of Distinct PLC Genes Identifies 'Compactness' as a Possible Architectural Shoot Strategy to Cope with Drought Stress.","authors":"Max van Hooren, Ringo van Wijk, Irina I Vaseva, Dominique Van Der Straeten, Michel Haring, Teun Munnik","doi":"10.1093/pcp/pcad123","DOIUrl":"10.1093/pcp/pcad123","url":null,"abstract":"<p><p>Phospholipase C (PLC) has been implicated in several stress responses, including drought. Overexpression (OE) of PLC has been shown to improve drought tolerance in various plant species. Arabidopsis contains nine PLC genes, which are subdivided into four clades. Earlier, OE of PLC3, PLC5 or PLC7 was found to increase Arabidopsis' drought tolerance. Here, we confirm this for three other PLCs: PLC2, the only constitutively expressed AtPLC; PLC4, reported to have reduced salt tolerance and PLC9, of which the encoded enzyme was presumed to be catalytically inactive. To compare each PLC and to discover any other potential phenotype, two independent OE lines of six AtPLC genes, representing all four clades, were simultaneously monitored with the GROWSCREEN-FLUORO phenotyping platform, under both control- and mild-drought conditions. To investigate which tissues were most relevant to achieving drought survival, we additionally expressed AtPLC5 using 13 different cell- or tissue-specific promoters. While no significant differences in plant size, biomass or photosynthesis were found between PLC lines and wild-type (WT) plants, all PLC-OE lines, as well as those tissue-specific lines that promoted drought survival, exhibited a stronger decrease in 'convex hull perimeter' (= increase in 'compactness') under water deprivation compared to WT. Increased compactness has not been associated with drought or decreased water loss before although a hyponastic decrease in compactness in response to increased temperatures has been associated with water loss. We propose that the increased compactness could lead to decreased water loss and potentially provide a new breeding trait to select for drought tolerance.</p>","PeriodicalId":20575,"journal":{"name":"Plant and Cell Physiology","volume":null,"pages":null},"PeriodicalIF":3.9,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11209554/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41238084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}