New Phytol , IF:8.512 , 2019 Jul , V223 (2) : P692-704 doi: 10.1111/nph.15669
Reactive oxygen species-mediated BIN2 activity revealed by single-molecule analysis.
State Key Laboratory of Surface Physics, Collaborative Innovation Center for Genetics and Development, Department of Physics, Fudan University, Shanghai, 200433, China.; Center of Integrative Biology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.; State Key Laboratory of Genetic Engineering, Collaborative Innovation Center for Genetics and Development, Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai, 200438, China.; Multiscale Research Institute for Complex Systems, Fudan University, Shanghai, 200438, China.
Much evidence has shown that reactive oxygen species (ROS) regulate several plant hormone signaling cascades, but little is known about the real-time kinetics and the underlying molecular mechanisms of the target proteins in the brassinosteroid (BR) signaling pathway. In this study, we used single-molecule techniques to investigate the true signaling timescales of the major BR signaling components BRI1-EMS-SUPPRESSOR 1 (BES1) and BRASSINOSTEROID INSENSITIVE 2 (BIN2) of Arabidopsis thaliana. The rate constants of BIN2 associating with ATP and phosphorylating BES1 were determined to be 0.7 +/- 0.4 mM(-1) s(-1) and 2.3 +/- 1.4 s(-1) , respectively. Interestingly, we found that the interaction of BIN2 and BES1 was oxygen-dependent, and oxygen can directly modify BIN2. The activity of BIN2 was switched on via modification of specific cysteine (Cys) residues, including C59, C95, C99 and C162. The mutation of these Cys residues inhibited the BR signaling outputs. These findings demonstrate the power of using single-molecule techniques to study the dynamic interactions of signaling components, which is difficult to be discovered by conventional physiological and biochemical methods.
PMID: 30597572
Rice (N Y) , IF:3.912 , 2019 Jul , V12 (1) : P53 doi: 10.1186/s12284-019-0313-y
The heterotrimeric G protein beta subunit RGB1 is required for seedling formation in rice.
Jiangsu Key Laboratory of Crop Genetics and Physiology/Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou, 225009, China.; Jiangsu Key Laboratory of Crop Genetics and Physiology/Key Laboratory of Plant Functional Genomics of the Ministry of Education/Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding, Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Agricultural College, Yangzhou University, Yangzhou, 225009, China. ricegb@yzu.edu.cn.
BACKGROUND: The heterotrimeric G protein beta subunit RGB1 plays an important role in plant growth and development. However, the molecular mechanisms underlying the regulation of rice growth by RGB1 remain elusive. RESULTS: Here, the rgb1 mutants rgb1-1 (+ 1 bp), rgb1-2 (- 1 bp), and rgb1-3 (- 11 bp) were isolated using the CRISPR/Cas9 system, and they were arrested at 1 day after germination and ultimately exhibited seedling lethality. The dynamic anatomical characteristics of the embryos of the rgb1 seedlings and WT during early postgermination and according to TUNEL assays showed that the suppressed growth of the rgb1 mutants was caused by cell death. In addition to the limited shoot and root development, the development of the embryo shoot-root axis was suppressed in the rgb1 mutants. RGB1 was expressed mainly in the root epidermal and vascular tissues of the embryo. Moreover, transcript profiling analysis revealed that the expression of a large number of auxin-, cytokinin-, and brassinosteroid-inducible genes was upregulated or downregulated in the rgb1 mutant compared to the wild type during seedling development. CONCLUSIONS: Overall, the rgb1 mutants provide an ideal material for exploring the molecular mechanism underlying rice seedling formation during early postgermination development by G proteins. SIGNIFICANCE STATEMENT: The heterotrimeric G protein beta subunit RGB1 acts as a crucial factor in promoting early postgermination seedling development in rice.
PMID: 31321558
BMC Plant Biol , IF:3.497 , 2019 Jul , V19 (1) : P288 doi: 10.1186/s12870-019-1902-z
Transcriptomic response in symptomless roots of clubroot infected kohlrabi (Brassica oleracea var. gongylodes) mirrors resistant plants.
University of Innsbruck, Institute of Microbiology, Technikerstrasse 25, 6020, Innsbruck, Austria.; Department of Plant Biology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Linnean Centre for Plant Biology, P.O. Box 7080, SE-75007, Uppsala, Sweden.; University of Innsbruck, Institute of Microbiology, Technikerstrasse 25, 6020, Innsbruck, Austria. Sigrid.Neuhauser@uibk.ac.at.
BACKGROUND: Clubroot disease caused by Plasmodiophora brassicae (Phytomyxea, Rhizaria) is one of the economically most important diseases of Brassica crops. The formation of hypertrophied roots accompanied by altered metabolism and hormone homeostasis is typical for infected plants. Not all roots of infected plants show the same phenotypic changes. While some roots remain uninfected, others develop galls of diverse size. The aim of this study was to analyse and compare the intra-plant heterogeneity of P. brassicae root galls and symptomless roots of the same host plants (Brassica oleracea var. gongylodes) collected from a commercial field in Austria using transcriptome analyses. RESULTS: Transcriptomes were markedly different between symptomless roots and gall tissue. Symptomless roots showed transcriptomic traits previously described for resistant plants. Genes involved in host cell wall synthesis and reinforcement were up-regulated in symptomless roots indicating elevated tolerance against P. brassicae. By contrast, genes involved in cell wall degradation and modification processes like expansion were up-regulated in root galls. Hormone metabolism differed between symptomless roots and galls. Brassinosteroid-synthesis was down-regulated in root galls, whereas jasmonic acid synthesis was down-regulated in symptomless roots. Cytokinin metabolism and signalling were up-regulated in symptomless roots with the exception of one CKX6 homolog, which was strongly down-regulated. Salicylic acid (SA) mediated defence response was up-regulated in symptomless roots, compared with root gall tissue. This is probably caused by a secreted benzoic acid/salicylic acid methyl transferase from the pathogen (PbBSMT), which was one of the highest expressed pathogen genes in gall tissue. The PbBSMT derived Methyl-SA potentially leads to increased pathogen tolerance in uninfected roots. CONCLUSIONS: Infected and uninfected roots of clubroot infected plants showed transcriptomic differences similar to those previously described between clubroot resistant and susceptible hosts. The here described intra-plant heterogeneity suggests, that for a better understanding of clubroot disease targeted, spatial analyses of clubroot infected plants will be vital in understanding this economically important disease.
PMID: 31262271
Funct Integr Genomics , IF:3.058 , 2019 Jul , V19 (4) : P597-615 doi: 10.1007/s10142-019-00668-1
High-throughput sequencing and differential expression analysis of miRNAs in response to Brassinosteroid treatment in Arabidopsis thaliana.
University School of Biotechnology, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi, 110078, India. gunjan.roy08@gmail.com.; University School of Biotechnology, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi, 110078, India.; University School of Biotechnology, Guru Gobind Singh Indraprastha University, Dwarka, New Delhi, 110078, India. meenukapoor@me.com.
Brassinosteroids are a class of phytohormones that play crucial roles in improving stress tolerance in plants. Many biochemical and physiological changes in response to abiotic stress are related to regulation of gene expression and accumulation of associated proteins. MicroRNAs (miRNAs) are class of small non-coding RNAs that regulate gene expression post-transcriptionally. Roles of these regulatory RNAs in brassinosteroid (BR) signalling have however remained elusive. In this study using high-throughput small RNA sequencing method, we present a comprehensive compilation of BR-induced differentially expressed microRNAs in root and shoots of Arabidopsis thaliana seedlings. We identified 229 known miRNAs belonging to 102 families and 27 novel miRNAs that express in response to exogenous BR treatment. Out of 102 families, miRNAs belonging to known 48 families and out of 27 novel miRNAs, 23 were observed to be differentially expressed in response to BR treatment. Among the conserved miRNAs, all members of miR169 were observed to be downregulated in both shoot and root samples. While, auxin-responsive factors were predicted to be direct targets of some novel miRNAs that are upregulated in shoots and suppressed in roots. The BR-responsive tissue-specific miRNome characterized in this study can be used as a starting point by investigators for functional validation studies that will shed light on the underlying molecular mechanism of BR-mediated stress tolerance at the level of post-transcriptional gene regulation.
PMID: 30783808
Physiol Mol Biol Plants , IF:2.005 , 2019 Jul , V25 (4) : P991-1008 doi: 10.1007/s12298-019-00685-1
Physiological and transcriptomic analysis highlight key metabolic pathways in relation to drought tolerance in Rhododendron delavayi.
1Flower Research Institute of Yunnan Academy of Agricultural Sciences, Kunming, Yunnan 650205 China.0000 0004 1799 1111grid.410732.3; National Engineering Research Center for Ornamental Horticulture, Kunming, Yunnan 650205 China.; 3Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650201 Yunnan China.0000000119573309grid.9227.e
Rhododendron delavayi is an alpine evergreen ornamental plant, but water shortage limits its growth and development in urban gardens. However, the adaptive mechanism of alpine evergreen rhododendrons to drought remains unclear. Here, a water control experiment was conducted to study the physiological and transcriptomic response of R. delavayi to drought. The drought treatment for 9 days decreased photosynthetic rate, induced accumulation of reactive oxygen species (ROS), and damaged chloroplast ultrastructure of R. delavayi. However, the photosynthetic rate quickly recovered to the level before treatment when the plants were re-watered. De novo assembly of RNA-Seq data generated 86,855 unigenes with an average length of 1870 bp. A total of 22,728 differentially expressed genes (DEGs) were identified between the control and drought plants. The expression of most DEGs related to photosynthesis were down-regulated during drought stress, and were up-regulated when the plants were re-watered, including the DEGs encoding subunits of light-harvesting chlorophyll-protein complex, photosystem II and photosystem I reaction center pigment-protein complexes, and photosynthetic electron transport. The expressions of many DEGs related to signal transduction, flavonoid biosynthesis and antioxidant activity were also significantly affected by drought stress. The results indicated that the response of R. delavayi to drought involved multiple physiological processes and metabolic pathways. Photosynthetic adjustment, ROS-scavenging system, abscisic acid and brassinosteroid signal transduction pathway may play important roles to improve drought tolerance of R. delavayi. Our findings provided valuable information for understanding the mechanisms of drought tolerance employed by Rhododendron species.
PMID: 31402822
Steroids , IF:1.948 , 2019 Jul , V147 : P28-36 doi: 10.1016/j.steroids.2019.04.002
Seed germination, respiratory processes and phosphatidic acid accumulation in Arabidopsis diacylglycerol kinase knockouts - The effect of brassinosteroid, brassinazole and salinity.
Department of the Molecular Mechanisms of Cell Metabolism Regulation, Kukhar Institute of Bioorganic Chemistry and Petrochemistry, The National Academy of Sciences of Ukraine, 02660, Murmanska str., 1, Kyiv, Ukraine.; Laboratory of Steroid Chemistry, Institute of Bioorganic Chemistry, The National Academy of Sciences of Belarus, 220141, Kuprevich str., 5, Minsk, Belarus.; Institute of Experimental Botany of the Czech Academy of Sciences, Prague, Czech Republic.; Department of the Molecular Mechanisms of Cell Metabolism Regulation, Kukhar Institute of Bioorganic Chemistry and Petrochemistry, The National Academy of Sciences of Ukraine, 02660, Murmanska str., 1, Kyiv, Ukraine. Electronic address: kravets@bpci.kiev.ua.
Using Arabidopsis thaliana wild type (WT) plants and diacylglycerol kinase knockouts (single mutants - dgk3, dgk1, dgk6; double mutants - dgk3dgk7, dgk5dgk6, dgk1dgk2) we observed that the inhibitor of brassinosteroid (BR) biosynthesis, brassinazole (BRZ), drastically decreased germination of dgk mutants under salt stress, while BRZ co-administration with 24-epibrassinolide (EBL) partially improved germination rates. We also observed a statistically significant decrease in alternative and cytochrome respiratory pathways in response to BRZ treatment under salinity conditions. We showed that production of the lipid second messenger phosphatidic acid (PA) is impaired in dgk mutants in response to EBL treatment and inhibitor of diacylglycerol kinase (DGK) - R59022. This study demonstrates that dgk mutants possess lower germination rates, lower total respiration rates, an alternative respiratory pathway and PA content under optimal and high salinity conditions in response to EBL treatment comparing to WT plants.
PMID: 30981682