Dev Cell , IF:10.092 , 2021 Feb , V56 (3) : P310-324.e7 doi: 10.1016/j.devcel.2020.12.001
A BIN2-GLK1 Signaling Module Integrates Brassinosteroid and Light Signaling to Repress Chloroplast Development in the Dark.
Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, P.R.China. Electronic address: zhdawei@scu.edu.cn.; Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, P.R.China.; Department of Genetics, Development, and Cell Biology, Iowa State University, Ames, IA, USA.; School of Life Science, Guangzhou University, Guangzhou, P.R.China.; Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, P.R.China. Electronic address: hhlin@scu.edu.cn.
Arabidopsis GLYCOGEN SYNTHASE KINASE 3 (GSK3)-like kinases play various roles in plant development, including chloroplast development, but the underlying molecular mechanism is not well defined. Here, we demonstrate that transcription factors GLK1 and GLK2 interact with and are phosphorylated by the BRASSINOSTEROID insensitive2 (BIN2). The loss-of-function mutant of BIN2 and its homologs, bin2-3 bil1 bil2, displays abnormal chloroplast development, whereas the gain-of-function mutant, bin2-1, exhibits insensitivity to BR-induced de-greening and reduced numbers of thylakoids per granum, suggesting that BIN2 positively regulates chloroplast development. Furthermore, BIN2 phosphorylates GLK1 at T175, T238, T248, and T256, and mutations of these phosphorylation sites alter GLK1 protein stability and DNA binding and impair plant responses to BRs/darkness. On the other hand, BRs and darkness repress the BIN2-GLK module to enhance BR/dark-mediated de-greening and impair the formation of the photosynthetic apparatus. Our results thus provide a mechanism by which BRs modulate photomorphogenesis and chloroplast development.
PMID: 33357403
New Phytol , IF:8.512 , 2021 Feb doi: 10.1111/nph.17265
Brassinosteroid-BZR1/2-WAT1 module determines the high level of auxin signalling in vascular cambium during wood formation.
Department of Biology, Chungbuk National University, Cheongju, 28644, Republic of Korea.; School of Biological Sciences, Seoul National University, Seoul, 08826, Korea.; Theragen Bio Co, Ltd, Suwon, 16229, Republic of Korea.; Department of Information and Statistics, Chungbuk National University, Cheongju, 28644, Republic of Korea.; Department of Forest Science, Chungbuk National University, Cheongju, 28644, Republic of Korea.; Department of Horticulture, Hankyong National University, Ansung, 17579, Republic of Korea.; Department of Industrial Plant Science and Technology, Chungbuk National University, Cheongju, s28644, Republic of Korea.
The tight regulation of local auxin homeostasis and signalling maxima in xylem precursor cells specifies the organizing activity of the vascular cambium and consequently promotes xylem differentiation and wood formation. However, the molecular mechanisms underlying the local auxin signalling maxima in the vascular cambium are largely unknown. Here, we reveal that brassinosteroid (BR)-activated WALLS ARE THIN1 (WAT1) facilitates wood formation by enhancing local auxin signalling in the vascular cambium in Solanum lycopersicum. Growth defects and low auxin signalling readouts in the BR-deficient tomato cultivar, Micro-Tom, were associated with a novel recessive allele, Slwat1-copi, created by the insertion of a retrotransposon in the last exon of the SlWAT1 locus. Molecular and genetic studies by generating the gain- and loss-of-function tomato mutants revealed that SlWAT1 is a critical regulator for fine-tuning local auxin homeostasis and signalling outputs in vascular cambium to facilitate secondary growth. Finally, we discovered that BR-regulated SlBZR1/2 directly activation of downstream auxin responses by SlWAT1 upregulation in xylem precursor cells to facilitate xylem differentiation and subsequent wood formation. Our data suggest that the BR-SlBZR1/2-WAT1 signalling network contributes to the high level of auxin signalling in the vascular cambium for secondary growth.
PMID: 33570747
Plant Physiol , IF:6.902 , 2021 Feb doi: 10.1093/plphys/kiab089
Brassinosteroids repress the seed maturation program during the seed-to-seedling transition.
State Key Laboratory of Biocontrol, Guangdong Provincial Key Laboratory of Plant Resource, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.; State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng 475001, China.; Agro-biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China.; Department of Plant Biology, Carnegie Institution for Science, Stanford, California, USA.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangdong Provincial Key Laboratory of Postharvest Science of Fruits and Vegetables, College of Horticultural Science, South China Agricultural University, Guangzhou, 510642, China.
In flowering plants, repression of the seed maturation program is essential for the transition from the seed to the vegetative phase, but the underlying mechanisms remain poorly understood. The B3-domain protein VIVIPAROUS1/ABSCISIC ACID INSENSITIVE3-LIKE 1 (VAL1) is involved in repressing the seed maturation program. Here we uncovered a molecular network triggered by the plant hormone brassinosteroid (BR) that inhibits the seed maturation program during the seed-to-seedling transition in Arabidopsis (Arabidopsis thaliana). val1-2 mutant seedlings treated with a BR biosynthesis inhibitor form embryonic structures, whereas BR signaling gain-of-function mutations rescue the embryonic structure trait. Furthermore, the BR-activated transcription factors BRI1-EMS-SUPPRESSOR 1 (BES1) and BRASSINAZOLE-RESISTANT 1 (BZR1) bind directly to the promoter of AGAMOUS-LIKE15 (AGL15), which encodes a transcription factor involved in activating the seed maturation program, and suppress its expression. Genetic analysis indicated that BR signaling is epistatic to AGL15 and represses the seed maturation program by downregulating AGL15. Finally, we showed that the BR-mediated pathway functions synergistically with the VAL1/2-mediated pathway to ensure the full repression of the seed maturation program. Together, our work uncovered a mechanism underlying the suppression of the seed maturation program, shedding light on how BR promotes seedling growth.
PMID: 33620498
Plant J , IF:6.141 , 2021 Feb , V105 (4) : P1053-1071 doi: 10.1111/tpj.15086
The AGCVIII kinase Dw2 modulates cell proliferation, endomembrane trafficking, and MLG/xylan cell wall localization in elongating stem internodes of Sorghum bicolor.
Department of Biochemistry & Biophysics, Texas A&M University, College Station, Texas, 77843, USA.; Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA.; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, Michigan, 48824, USA.; MSU-DOE Plant Research Lab, Michigan State University, East Lansing, Michigan, 48824, USA.; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824, USA.
Stems of bioenergy sorghum (Sorghum bicolor L. Moench.), a drought-tolerant C4 grass, contain up to 50 nodes and internodes of varying length that span 4-5 m and account for approximately 84% of harvested biomass. Stem internode growth impacts plant height and biomass accumulation and is regulated by brassinosteroid signaling, auxin transport, and gibberellin biosynthesis. In addition, an AGCVIII kinase (Dw2) regulates sorghum stem internode growth, but the underlying mechanism and signaling network are unknown. Here we provide evidence that mutation of Dw2 reduces cell proliferation in internode intercalary meristems, inhibits endocytosis, and alters the distribution of heteroxylan and mixed linkage glucan in cell walls. Phosphoproteomic analysis showed that Dw2 signaling influences the phosphorylation of proteins involved in lipid signaling (PLDdelta), endomembrane trafficking, hormone, light, and receptor signaling, and photosynthesis. Together, our results show that Dw2 modulates endomembrane function and cell division during sorghum internode growth, providing insight into the regulation of monocot stem development.
PMID: 33211340
J Exp Bot , IF:5.908 , 2021 Feb , V72 (4) : P1449-1459 doi: 10.1093/jxb/eraa524
An S-ribonuclease binding protein EBS1 and brassinolide signaling are specifically required for Arabidopsis tolerance to bicarbonate.
State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Lin'an, Hangzhou, China.; Key Laboratory of Saline-Alkali Vegetation Ecology Restoration, Ministry of Education, College of Life Science, Northeast Forestry University, Harbin, China.; School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore.; State Key Laboratory of Cotton Biology, Department of Biology, Institute of Plant Stress Biology, Henan University, Kaifeng, China.
Bicarbonate (NaHCO3) present in soils is usually considered to be a mixed stress for plants, with salts and high pH. NaHCO3-specific signaling in plants has rarely been reported. In this study, transcriptome analyses were conducted in order to identify NaHCO3-specific signaling in Arabidopsis. Weighted correlation network analysis was performed to isolate NaHCO3-specific modules in comparison with acetate treatment. The genes in the NaHCO3-root-specific module, which exhibited opposite expression to that in sodium acetate treatments, were further examined with their corresponding knock-out mutants. The gene Exclusively Bicarbonate Sensitive 1 (EBS1) encoding an S-ribonuclease binding protein, was identified to be specifically involved in plant tolerance to NaHCO3, but not to the other two alkaline salts, acetate and phosphate. We also identified the genes that are commonly regulated by bicarbonate, acetate and phosphate. Multiple brassinosteroid-associated gene ontology terms were enriched in these genes. Genetic assays showed that brassinosteroid signaling positively regulated plant tolerance to NaHCO3 stress, but negatively regulated tolerance to acetate and phosphate. Overall, our data identified bicarbonate-specific genes, and confirmed that alkaline stress is mainly dependent on the specificities of the weak acid ions, rather than high pH.
PMID: 33165537
J Exp Bot , IF:5.908 , 2021 Feb , V72 (4) : P1181-1197 doi: 10.1093/jxb/eraa495
The conserved brassinosteroid-related transcription factor BIM1a negatively regulates fruit growth in tomato.
INRAE, Univ. Bordeaux, UMR BFP, 33882, Villenave d'Ornon, France.; Instituto de Biotecnologia, Instituto Nacional de Tecnologia Agropecuaria, Consejo Nacional de Investigaciones Cientificas y Tecnicas, B1712WAA Castelar, Argentina.; Department of Plant Life Science, Faculty of Agriculture, Ryukoku University, Otsu, Shiga, Japan.; Department of Natural Sciences, International Christian University, Mitaka, Tokyo, Japan.; Faculty of Life and Environmental Sciences, University of Tsukuba, Tskuba, Ibaraki, Japan.; Tsukuba Plant Innovation Research Center, University of Tsukuba, Tskuba, Ibaraki, Japan.
Brassinosteroids (BRs) are steroid hormones that play key roles in plant development and defense. Our goal is to harness the extensive knowledge of the Arabidopsis BR signaling network to improve productivity in crop species. This first requires identifying components of the conserved network and their function in the target species. Here, we investigated the function of SlBIM1a, the closest tomato homolog of AtBIM1, which is highly expressed in fruit. SlBIM1a-overexpressing lines displayed severe plant and fruit dwarfism, and histological characterization of different transgenic lines revealed that SlBIM1a expression negatively correlated with fruit pericarp cell size, resulting in fruit size modifications. These growth phenotypes were in contrast to those found in Arabidopsis, and this was confirmed by the reciprocal ectopic expression of SlBIM1a/b in Arabidopsis and of AtBIM1 in tomato. These results determined that BIM1 function depends more on the recipient species than on its primary sequence. Yeast two-hybrid interaction studies and transcriptomic analyses of SlBIM1a-overexpressing fruit further suggested that SlBIM1a acts through its interaction with SlBZH1 to govern the transcriptional regulation of growth-related BR target genes. Together, these results suggest that SlBIM1a is a negative regulator of pericarp cell expansion, possibly at the crossroads with auxin and light signaling.
PMID: 33097930
Theor Appl Genet , IF:4.439 , 2021 Feb , V134 (2) : P633-645 doi: 10.1007/s00122-020-03719-5
Multiple origins of Indian dwarf wheat by mutations targeting the TREE domain of a GSK3-like kinase for drought tolerance, phosphate uptake, and grain quality.
252 McFadden Biostress Laboratory, Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA.; Plant Pathology Department, Kansas State University, Manhattan, KS, 66502, USA.; Institute of Experimental Botany of the Czech Academy of Sciences, 77900, Olomouc, Czech Republic.; 252 McFadden Biostress Laboratory, Department of Biology and Microbiology, South Dakota State University, Brookings, SD, 57007, USA. Wanlong.li@sdstate.edu.
KEY MESSAGE: Multiple origins of Indian dwarf wheat were due to two mutations targeting the same TREE domain of a GSK3-like kinase, and these mutations confer to enhanced drought tolerance and increased phosphate and nitrogen accumulation for adaptation to the dry climate of Indian and Pakistan. Indian dwarf wheat, featured by the short stature, erect leaves, dense spikes, and small, spherical grains, was a staple crop in India and Pakistan from the Bronze Age until the early 1900s. These morphological features are controlled by a single locus Sphaerococcum 1 (S1), but the genetic identity of the locus and molecular mechanisms underlying the selection of this wheat type are unknown. In this study, we showed that the origin of Indian dwarf wheat was due to two independent missense mutations targeting the conserved TREE domain of a GSK3-like kinase, which is homologous to the Arabidopsis BIN2 protein, a negative regulator in brassinosteroid signaling. The S1 protein is involved in brassinosteroid signaling by physical interaction with the wheat BES1/BZR1 proteins. The dwarf alleles are insensitive to brassinosteroid, upregulates brassinosteroid biosynthetic genes, significantly enhanced drought tolerance, facilitated phosphate accumulation, and increased high molecular weight glutenins. It is the enhanced drought tolerance and accumulation of nitrogen and phosphate that contributed to the adaptation of such a small-grain form of wheat to the dry climate of India and Pakistan. Thus, our research not only identified the genetic events underlying the origin of the Indian dwarf wheat, but also revealed the function of brassinosteroid in the regulation of drought tolerance, phosphate homeostasis, and grain quality.
PMID: 33164159
Plant Cell Physiol , IF:4.062 , 2021 Feb doi: 10.1093/pcp/pcab024
Brassinosteroids Influence Arabidopsis Hypocotyl Graviresponses Through Changes In Mannans And Cellulose.
School of Biosciences, University of Melbourne, Parkville, Melbourne, VIC 3010, Australia.; Laboratory of Functional Plant Biology, Department of Biology, Ghent University, K.L. Ledeganckstraat 35, Gent, B-9000, Belgium.; Max-Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, Potsdam, 14476, Germany.; Biology Department, Integrated Molecular Plant Physiology Research, University of Antwerp, Groenenborgerlaan 171, Antwerpen, 2020, Belgium.; Plant Biochemistry and Biotechnology Lab, Department of Agriculture, Hellenic Mediterranean University, Stavromenos, Heraklion, 71410, Crete, Greece.; Joint International Research Laboratory of Metabolic & Developmental Sciences, State Key Laboratory of Hybrid Rice, SJTU-University of Adelaide Joint Centre for Agriculture and Health, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.; Department of Plant & Environmental Sciences, University of Copenhagen, 1871, Frederiksberg C, Denmark.; Copenhagen Plant Science Center, University of Copenhagen, 1871, Frederiksberg C, Denmark.; Saint Petersburg State University, Department of Plant Physiology and Biochemistry, Faculty of Biology, Universitetskaya emb. 7/9, Saint Petersburg, 199034, Russia.
The force of gravity is a constant environmental factor. Plant shoots respond to gravity through negative gravitropism and gravity resistance. These responses are essential for plants to direct the growth of aerial organs away from the soil surface after germination and to keep an upright posture above ground. We took advantage of the effect of brassinosteroids on the two types of graviresponses in Arabidopsis thaliana hypocotyls to disentangle functions of cell wall polymers during etiolated shoot growth. The ability of etiolated Arabidopsis seedlings to grow upwards was suppressed in the presence of 24-epibrassinolide (EBL) but enhanced in the presence of brassinazole (BRZ), an inhibitor of brassinosteroid biosynthesis. These effects were accompanied by changes in cell wall mechanics and composition. Cell wall biochemical analyses, confocal microscopy of the cellulose-specific pontamine S4B dye and cellular growth analyses revealed that the EBL and BRZ treatments correlated with changes in cellulose fibre organization, cell expansion at the hypocotyl base and mannan content. Indeed, a longitudinal re-orientation of cellulose fibres and growth inhibition at the base of hypocotyls supported their upright posture whereas the presence of mannans reduced gravitropic bending. The negative effect of mannans on gravitropism is a new function for this class of hemicelluloses. We also found that EBL interferes with upright growth of hypocotyls through their uneven thickening at the base.
PMID: 33570567
Tree Physiol , IF:3.655 , 2021 Feb doi: 10.1093/treephys/tpab025
Unraveling hydrogen sulfide-promoted lateral root development and growth in mangrove plant Kandelia obovata: Insight into regulatory mechanism by TMT-based quantitative proteomic approaches.
Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361005, P.R. China.
Mangroves are the main intertidal ecosystems with varieties of root types along the tropical and subtropical coastlines around the world. The typical characteristics of mangrove habitats, including the abundant organic matter and nutrients, as well as the strong reductive environment, are favor for the production of hydrogen sulfide (H2S). H2S, as a pivotal signaling molecule, has been evidenced in a wide variety of plant physiological and developmental processes. However, whether H2S functions in the mangrove root system establishment is not clear yet. Here, we reported the possible role of H2S in regulation of Kandelia obovata root development and growth by TMT-based quantitative proteomic approaches coupled with bioinformatic methods. The results showed that H2S could induce the root morphogenesis of K. obovata in a dose-dependent manner. The proteomic results successfully identified 8,075 proteins, and 697 were determined as differentially expressed proteins. Based on the functional enrichment analysis, we demonstrated that H2S could promote the lateral root development and growth by predominantly regulating the proteins associated with carbohydrate metabolism, sulfur metabolism, glutathione metabolism and other antioxidant associated proteins. In addition, transcriptional regulation and brassinosteroid signal transduction associated proteins also act as important roles in lateral root development. The protein-protein interaction analysis further unravels a complicated regulation network of carbohydrate metabolism, cellular redox homeostasis, protein metabolism, secondary metabolism, and amino acid metabolism in H2S-promoted root development and growth of K. obovata. Overall, our results revealed that H2S could contribute to the morphogenesis of the unique root system of mangrove plant K. obovata, and play a positive role in the adaption of mangrove plants to intertidal habitats.
PMID: 33580961
BMC Plant Biol , IF:3.497 , 2021 Feb , V21 (1) : P98 doi: 10.1186/s12870-021-02877-y
Integrated metabolic profiling and transcriptome analysis of pigment accumulation in Lonicera japonica flower petals during colour-transition.
Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education; College of Horticulture and Landscape Architecture, Southwest University, Chongqing, 400715, China.; Academy of Agricultural Sciences of Southwest University, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing, 400715, China.; Henan International Joint Laboratory of Crop Gene Resources and Improvement, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, Henan, China.; Rare Plant Research Institute of the Yangtze River (Yichang); Institute of Science and Technology, China Three Gorges Corporation, Beijing, 100083, China.; Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education; College of Horticulture and Landscape Architecture, Southwest University, Chongqing, 400715, China. qgguo@126.com.; Academy of Agricultural Sciences of Southwest University, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing, 400715, China. qgguo@126.com.; Key Laboratory of Horticulture Science for Southern Mountains Regions of Ministry of Education; College of Horticulture and Landscape Architecture, Southwest University, Chongqing, 400715, China. lianggl@swu.edu.cn.; Academy of Agricultural Sciences of Southwest University, State Cultivation Base of Crop Stress Biology for Southern Mountainous Land of Southwest University, Chongqing, 400715, China. lianggl@swu.edu.cn.
BACKGROUND: Plants have remarkable diversity in petal colour through the biosynthesis and accumulation of various pigments. To better understand the mechanisms regulating petal pigmentation in Lonicera japonica, we used multiple approaches to investigate the changes in carotenoids, anthocyanins, endogenous hormones and gene expression dynamics during petal colour transitions, i.e., green bud petals (GB_Pe), white flower petals (WF_Pe) and yellow flower petals (YF_Pe). RESULTS: Metabolome analysis showed that YF_Pe contained a much higher content of carotenoids than GB_Pe and WF_Pe, with alpha-carotene, zeaxanthin, violaxanthin and gamma-carotene identified as the major carotenoid compounds in YF_Pe. Comparative transcriptome analysis revealed that the key differentially expressed genes (DEGs) involved in carotenoid biosynthesis, such as phytoene synthase, phytoene desaturase and zeta-carotene desaturase, were significantly upregulated in YF_Pe. The results indicated that upregulated carotenoid concentrations and carotenoid biosynthesis-related genes predominantly promote colour transition. Meanwhile, two anthocyanins (pelargonidin and cyanidin) were significantly increased in YF_Pe, and the expression level of an anthocyanidin synthase gene was significantly upregulated, suggesting that anthocyanins may contribute to vivid yellow colour in YF_Pe. Furthermore, analyses of changes in indoleacetic acid, zeatin riboside, gibberellic acid, brassinosteroid (BR), methyl jasmonate and abscisic acid (ABA) levels indicated that colour transitions are regulated by endogenous hormones. The DEGs involved in the auxin, cytokinin, gibberellin, BR, jasmonic acid and ABA signalling pathways were enriched and associated with petal colour transitions. CONCLUSION: Our results provide global insight into the pigment accumulation and the regulatory mechanisms underlying petal colour transitions during the flower development process in L. japonica.
PMID: 33596836
AoB Plants , IF:2.182 , 2021 Feb , V13 (1) : Pplaa071 doi: 10.1093/aobpla/plaa071
Early transcriptional response to gravistimulation in poplar without phototropic confounding factors.
CIRAD, UMR AGAP, Montpellier, France.; AGAP, Univ Montpellier, CIRAD, INRAE, Institut Agro, Montpellier, France.; Universite Clermont Auvergne, INRAE, PIAF, Campus Universitaire des Cezeaux, 1 Impasse Amelie Murat, TSA, Aubiere Cedex, France.; Universite Clermont Auvergne, GReD INSERM U1103-CNRS UMR 6293, Faculte de Medecine, CRBC (Centre de Recherche Bio-Clinique), Clermont-Ferrand, France.; INRAE, UR 115 PSH, Centre de recherche PACA, 228, route de l'aerodrome, CS, Avignon Cedex, France.
In response to gravistimulation under anisotropic light, tree stems showing an active cambium produce reaction wood that redirects the axis of the trees. Several studies have described transcriptomic or proteomic models of reaction wood relative to the opposite wood. However, the mechanisms leading to the formation of reaction wood are difficult to decipher because so many environmental factors can induce various signalling pathways leading to this developmental reprogramming. Using an innovative isotropic device where the phototropic response does not interfere with gravistimulation we characterized the early molecular responses occurring in the stem of poplar after gravistimulation in an isotropic environment, and without deformation of the stem. After 30 min tilting at 35 degrees under anisotropic light, we collected the upper and lower xylems from the inclined stems. Controls were collected from vertical stems. We used a microarray approach to identify differentially expressed transcripts. High-throughput real-time PCR allowed a kinetic experiment at 0, 30, 120 and 180 min after tilting at 35 degrees , with candidate genes. We identified 668 differentially expressed transcripts, from which we selected 153 candidates for additional Fluidigm qPCR assessment. Five candidate co-expression gene clusters have been identified after the kinetic monitoring of the expression of candidate genes. Gene ontology analyses indicate that molecular reprogramming of processes such as 'wood cell expansion', 'cell wall reorganization' and 'programmed cell death' occur as early as 30 min after gravistimulation. Of note is that the change in the expression of different genes involves a fine regulation of gibberellin and brassinosteroid pathways as well as flavonoid and phosphoinositide pathways. Our experimental set-up allowed the identification of genes regulated in early gravitropic response without the bias introduced by phototropic and stem bending responses.
PMID: 33542802
Plant Signal Behav , IF:1.671 , 2021 Feb , V16 (2) : P1850625 doi: 10.1080/15592324.2020.1850625
BES1 negatively regulates the expression of ACC oxidase 2 to control the endogenous level of ethylene in Arabidopsis thaliana.
Department of Life Science, Chung-Ang University , Seoul, Republic of Korea.; Department of Biological Science, Andong National University , Andong, Republic of Korea.; Department of Plant Biology, Carnegie Institution for Science , Standford, CA, USA.
Quantitative reverse transcription PCR (qRT-PCR) analysis and ProACO2::GUS expression showed that ACO2 was highly expressed in the shoots of Arabidopsis seedlings under light conditions. Exogenously applied aminocyclopropane-1-carboxylic acid (ACC) enhanced the expression of ACO2, whereas Co(2+) ions suppressed its expression. In comparison with wild-type seedlings, the ACO2 knockdown mutant aco2-1 produced less ethylene, which resulted in the inhibited growth of Arabidopsis seedlings. Exogenously applied brassinolide reduced the expression of ACO2. ACO2 expression was increased in det2, a brassinosteroid (BR)-deficient mutant; however, it was decreased in bes1-D, a brassinosteroid insensitive 1-EMS-suppressor 1 (BES1)-dominant mutant. In the putative promoter region of ACO2, 11 E-box sequences for BES1 binding but not BR regulatory element sequences for brassinazole-resistant 1 (BZR1) binding were found. Chromatin immunoprecipitation assay showed that BES1 could directly bind to the E-boxes located in the putative promoter region of ACO4. Less ethylene was produced in bes1-D seedlings compared with wild-type seedlings, suggesting that the direct binding of BES1 to the ACO2 promoter may negatively regulate ACO2 expression to control the endogenous level of ethylene in Arabidopsis seedlings.
PMID: 33258709