Autophagy , IF:9.77 , 2020 Aug : P1-18 doi: 10.1080/15548627.2020.1810426
Phosphorylation of ATG18a by BAK1 suppresses autophagy and attenuates plant resistance against necrotrophic pathogens.
National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University , Wuhan, China.; Ecology College, Lishui University , Lishui, China.; State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University , Wuhan, China.
Autophagy is critical for plant defense against necrotrophic pathogens, which causes serious yield loss on crops. However, the post-translational regulatory mechanisms of autophagy pathway in plant resistance against necrotrophs remain poorly understood. In this study, we report that phosphorylation modification on ATG18a, a key regulator of autophagosome formation in Arabidopsis thaliana, constitutes a post-translation regulation of autophagy, which attenuates plant resistance against necrotrophic pathogens. We found that phosphorylation of ATG18a suppresses autophagosome formation and its subsequent delivery into the vacuole, which results in reduced autophagy activity and compromised plant resistance against Botrytis cinerea. In contrast, overexpression of ATG18a dephosphorylation-mimic form increases the accumulation of autophagosomes and complements the plant resistance of atg18a mutant against B. cinerea. Moreover, BAK1, a key regulator in plant resistance, was identified to physically interact with and phosphorylate ATG18a. Mutation of BAK1 blocks ATG18a phosphorylation at four of the five detected phosphorylation sites after B. cinerea infection and strongly activates autophagy, leading to enhanced resistance against B. cinerea. Collectively, the identification of functional phosphorylation sites on ATG18a and the corresponding kinase BAK1 unveiled how plant regulates autophagy during resistance against necrotrophic pathogens. ABBREVIATIONS: 35s: the cauliflower mosaic virus 35s promoter; A. thaliana: Arabidopsis thaliana; A. brassicicola: Alternaria brassicicola; ABA: abscisic acid; ATG: autophagy-related; ATG18a: autophagy-related protein 18a in A. thaliana; ATG8a: autophagy-related protein 8a in A. thaliana; ATG8-PE: ATG8 conjugated with PE; B. cinerea: Botrytis cinerea; BAK1: Brassinosteroid insensitive 1-associated receptor kinase1 in A. thaliana; BiFC: biomolecular fluorescence complementation; BIK1: Botrytis-insensitive kinase 1 in A. thaliana; BKK1: BAK1-like 1 in A. thaliana; BR: brassinosteroid; Co-IP: coimmunoprecipitation; dai: days after inoculation; DAMPs: damage-associated molecular patterns; E. coli: Escherochia coli; ER: endoplasmic reticulum; ETI: effector-triggered immunity; GFP: green fluorescent protein; HA: hemagglutinin; IP: immunoprecipitation; LC-MS/MS: liquid chromatography-tandem mass spectrometry; LCI: luciferase complementation imaging; MPK3: mitogen-activated protein kinase 3 in A. thaliana; MPK4: mitogen-activated protein kinase 4 in A. thaliana; MPK6: mitogen-activated protein kinase 6 in A. thaliana; N. benthamiana: Nicotiana benthamiana; NES: nuclear export sequence; PAMP: pathogen-associated molecular pattern; PCR: polymerase chain reaction; PE: phosphatidylethanolamine; PRR: pattern recognition receptor; PtdIns(3,5)P2: phosphatidylinositol (3,5)-biphosphate; PtdIns3P: phosphatidylinositol 3-biphosphate; PTI: PAMP-triggered immunity; qRT-PCR: quantitative reverse transcription PCR; SnRK2.6: SNF1-related protein kinase 2.6 in A. thaliana; TORC1: the rapamycin-sensitive Tor complex1; TRAF: tumor necrosis factor receptor-associated factor; WT: wild type plant; Yc: C-terminal fragment of YFP; YFP: yellow fluorescent protein; Yn: N-terminal fragment of YFP.
PMID: 32804012
Plant Cell , IF:9.618 , 2020 Aug doi: 10.1105/tpc.20.00138
Constitutive Activation of Leucine-Rich Repeat Receptor Kinase Signaling Pathways by BAK1-Interacting Receptor-Like Kinase 3 Chimera.
Department of Botany and Plant Biology, University of Geneva, 1211 Geneva, Switzerland CITY: Geneva STATE: GE Switzerland [CH].; University of Geneva CITY: Geneva Switzerland [CH].; Department of Cell Biology, Max Planck Institute for Developmental Biology, 72076 Tuebingen, Germany. CITY: Tuebingen Germany [DE].; University of Geneva CITY: Geneva POSTAL_CODE: 1015 Switzerland [CH].; Max Planck Institute for Developmental Biology CITY: Tuebingen POSTAL_CODE: 72076 Germany [DE].; University of Geneva CITY: Geneva STATE: GE POSTAL_CODE: 7076 Switzerland [CH] Michael.Hothorn@unige.ch.
Receptor kinases with extracellular leucine-rich repeat domains (LRR-RKs) form the largest group of membrane signaling proteins in plants. LRR-RKs can sense small molecule, peptide, or protein ligands, and may be activated by ligand-induced interaction with a shape complementary SOMATIC EMBRYOGENESIS RECEPTOR-LIKE KINASE (SERK) co-receptor kinase. We have previously shown that SERKs can also form constitutive, ligand-independent complexes with the LRR ectodomains of BAK1-interacting receptor-like kinase 3 (BIR3) receptor pseudokinases, negative regulators of LRR-RK signaling. Here we report that receptor chimera in which the extracellular LRR domain of BIR3 is fused to the cytoplasmic kinase domains of the SERK-dependent LRR-RKs BRASSINOSTEROID INSENSITIVE1, HAESA and ERECTA form tight complexes with endogenous SERK co-receptors in the absence of ligand stimulus. Expression of these chimeras under the control of the endogenous promoter of the respective LRR-RK leads to strong gain-of-function brassinosteroid, floral abscission, and stomatal patterning phenotypes, respectively. Importantly, a BIR3-GSO1/SGN3 chimera can partially complement sgn3 Casparian strip formation phenotypes, suggesting that SERK proteins also mediate GSO1/SGN3 receptor activation. Collectively, our protein engineering approach may be used to elucidate the physiological functions of orphan LRR-RKs and to identify their receptor activation mechanism in single transgenic lines.
PMID: 32796127
Plant Cell , IF:9.618 , 2020 Aug doi: 10.1105/tpc.20.00048
Brassinosteroid-Activated BRI1-EMS-SUPPRESSOR 1 Inhibits Flavonoid Biosynthesis and Coordinates Growth and UV-B Stress Responses in Plants.
Chinese Academy of Sciences CITY: Shanghai China [CN].; Institute of Genetics and Developmental Biology CITY: Beijing United States Of America [US].; Institute of Genetics and Developmental Biology, CAS CITY: Beijing China [CN].; Shanghai Normal University CITY: Shanghai STATE: Shanghai POSTAL_CODE: 200032 China [CN].; Iowa State University CITY: Ames STATE: Iowa POSTAL_CODE: 50011-3650 United States Of America [US].; Chinese Academy of Sciences CITY: Shanghai POSTAL_CODE: 200032 China [CN] htliu@cemps.ac.cn.
Ultraviolet B (UV-B) light is a potential stress factor in plants, but how plants coordinate growth and UV-B stress responses is not well understood. Here we report that brassinosteroid (BR) signaling inhibits UV-B stress responses in Arabidopsis thaliana and various crops by controlling flavonol biosynthesis. We further demonstrate that BRI1-EMS-SUPPRESSOR 1 (BES1) mediates the tradeoff between plant growth and UV-B defense responses. BES1, a master transcription factor involved in BR signaling, represses the expression of transcription factor genes MYB11, MYB12, and MYB111, which activate flavonol biosynthesis. BES1 directly binds to the promoters of these MYBs in a BR-enhanced manner to repress their expression, thereby reducing flavonol accumulation. However, exposure to broad-band UV-B, primarily low-wavelength high-energy UV-B light, down-regulates BES1 expression, thus promoting flavonol accumulation. These findings demonstrate that BR-activated BES1 not only promotes growth but also inhibits flavonoid biosynthesis. UV-B stress suppresses the expression of BES1 to allocate energy to flavonoid biosynthesis and UV-B stress responses, allowing plants to switch from growth to UV-B stress responses in a timely manner.
PMID: 32796123
Proc Natl Acad Sci U S A , IF:9.412 , 2020 Aug doi: 10.1073/pnas.2002278117
DROOPY LEAF1 controls leaf architecture by orchestrating early brassinosteroid signaling.
Key Laboratory of Agricultural Water Resources, Hebei Laboratory of Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, 050021 Shijiazhuang, China.; Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081 Beijing, China.; College of Life Sciences, Shanxi Agricultural University, Taigu, 030801 Shanxi, China.; Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaboration Innovation Center for Cell Signaling, Hebei Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, 050024 Shijiazhuang, China.; State Key Laboratory of Plant Genomics, and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, 100101 Beijing, China.; University of Chinese Academy of Sciences, 100039 Beijing, China.; Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, 100081 Beijing, China; wuchuanyin@caas.cn xgliu@sjziam.ac.cn diaoxianmin@caas.cn.; Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaboration Innovation Center for Cell Signaling, Hebei Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, 050024 Shijiazhuang, China; wuchuanyin@caas.cn xgliu@sjziam.ac.cn diaoxianmin@caas.cn.; State Key Laboratory of Plant Cell and Chromosome Engineering, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, 050021 Shijiazhuang, China.
Leaf architecture directly determines canopy structure, and thus, grain yield in crops. Leaf droopiness is an agronomic trait primarily affecting the cereal leaf architecture but the genetic basis and underlying molecular mechanism of this trait remain unclear. Here, we report that DROOPY LEAF1 (DPY1), an LRR receptor-like kinase, plays a crucial role in determining leaf droopiness by controlling the brassinosteroid (BR) signaling output in Setaria, an emerging model for Panicoideae grasses. Loss-of-function mutation in DPY1 led to malformation of vascular sclerenchyma and low lignin content in leaves, and thus, an extremely droopy leaf phenotype, consistent with its preferential expression in leaf vascular tissues. DPY1 interacts with and competes for SiBAK1 and as a result, causes a sequential reduction in SiBRI1-SiBAK1 interaction, SiBRI1 phosphorylation, and downstream BR signaling. Conversely, DPY1 accumulation and affinity of the DPY1-SiBAK1 interaction are enhanced under BR treatment, thus preventing SiBRI1 from overactivation. As such, those findings reveal a negative feedback mechanism that represses leaf droopiness by preventing an overresponse of early BR signaling to excess BRs. Notably, plants overexpressing DPY1 have more upright leaves, thicker stems, and bigger panicles, suggesting potential utilization for yield improvement. The maize ortholog of DPY1 rescues the droopy leaves in dpy1, suggesting its conserved function in Panicoideae. Together, our study provides insights into how BR signaling is scrutinized by DPY1 to ensure the upward leaf architecture.
PMID: 32817516
New Phytol , IF:8.512 , 2020 Aug doi: 10.1111/nph.16840
HBI1 acts downstream of ERECTA and SWR1 in regulating inflorescence architecture through the activation of the brassinosteroid and auxin signaling pathways.
Key Laboratory of Genetics, Breeding and Multiple Utilization of Crops, Ministry of Education, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Agriculture, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.; State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi Key Lab of Sugarcane Biology, College of Agriculture, Guangxi University, Nanning, 530004, China.
Inflorescence architecture critically influences plant reproductive success and crop yield, and it reflects the activity of the inflorescence meristem and pedicel length. In Arabidopsis thaliana, the ERECTA (ER) signaling pathway and the SWR1 chromatin remodeling complex jointly regulate inflorescence architecture by promoting the expression of the PACLOBUTRAZOL RESISTANCE (PRE) gene family. However, how PREs regulate inflorescence architecture remains unclear. RNA-seq and chromatin immunoprecipitation coupled with quantitative PCR (ChIP-qPCR) analyses were performed. Genetic interactions between HOMOLOG OF BEE2 INTERACTING WITH IBH1 (HBI1) and SWR1-ER-MPK6 pathway in the control of Inflorescence architecture were further studied. The present findings support that HBI1 functions downstream of PREs in the SWR1 and ER pathways to regulate inflorescence architecture by promoting pedicel elongation. Specifically, it binds to the promoters of the brassinosteroid (BR) biosynthesis gene CYP85A2 and a series of auxin-related genes including auxin response factor ARF3 and promotes their expression. In turn, ARF3 can also bind to auxin signaling genes as well as CYP85A2 to activate their expression and promote pedicel elongation. Our study provides evidence that inflorescence architecture regulation by SWR1 and ER involves the HBI1 regulatory hub and its activation of both the BR and auxin hormone pathways.
PMID: 32746499
Plant Physiol , IF:6.902 , 2020 Aug doi: 10.1104/pp.20.00386
Comparative transcriptomic analysis to identify brassinosteroid response genes.
Shanghai Center for Plant Stress Biology CITY: Shanghai STATE: Shanghai China [CN] liuxiaolei@sibs.ac.cn.; Chinese Academy of Sciences CITY: Shanghai POSTAL_CODE: 201602 China [CN].; Institute of Integrative Genome Biology, University of California CITY: Riverside United States Of America [US].; Shanghai Center for Plant Stress Biology CITY: Shanghai STATE: Shanghai China [CN].; University of Michigan CITY: Ann Arbor United States Of America [US].
Brassinosteroids (BRs) are plant growth-promoting steroid hormones. BRs affect plant growth by regulating panels of downstream genes. Much effort has been made to establish BR-regulated gene expression networks, but there is little overlap among published expression networks. In this study, we built an optimal BR-regulated gene expression network using the model plant Arabidopisis (Arabidopisis thaliana). Seven- and 24-day-old seedlings of the constitutive photomorphogenesis and dwarfism (cpd) mutant and bri1-701 (brassinosteroid-insensitive 1-701) brl1 (BRI1-like receptor genes 1) brl3 triple mutant seedlings were treated with brassinolide (BL), and RNA sequencing (RNA-seq) was used to detect differentially expressed genes (DEGs). Using this approach, we generated a transcriptomic database of 4498 DEGs and identified 110 transcription factors that specifically respond to BR at different stages. We also found that, among the identified BR-responsive transcription factors, ABSCISIC ACID-INSENSlTIVE4 (ABI4), an ethylene response factor (ERF) transcription factor, inhibits BR-regulated growth. Compared to wild-type plants, the abi4-102 mutant was less sensitive to brassinazole (BRZ) and more sensitive to BR. Next, we performed a chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq) assay and established that ABI4 binds directly to the BAK1 (BRI1-associated receptor kinase 1) promoter and inhibits transcription. These results provide insight into BR-responsive gene functions in regulating plant growth at different stages and may serve as a basis for predicting gene function, selecting candidate genes, and improving the understanding of BR regulatory pathways.
PMID: 32759270
Genes (Basel) , IF:3.759 , 2020 Aug , V11 (8) doi: 10.3390/genes11080919
Brassinosteroid Priming Improves Peanut Drought Tolerance via Eliminating Inhibition on Genes in Photosynthesis and Hormone Signaling.
Guangdong Key Laboratory of Plant Molecular Breeding, State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Agriculture, South China Agricultural University, Guangzhou 510642, China.; Department of Genetics, University of Georgia, Athens, GA 30602, USA.
Drought negatively affects the growth and yield of terrestrial crops. Seed priming, pre-exposing seed to a compound, could induce improved tolerance and adaptation to stress in germinated plants. To understand the effects and regulatory mechanism of seed priming with brassinosteroid (BR) on peanut plants, we treated seeds with five BR concentrations and examined dozens of physiological and biochemical features, and transcriptomic changes in leaves under well-watered and drought conditions. We found optimal 0.15 ppm BR priming could reduce inhibitions from drought and increase the yield of peanut, and priming effects are dependent on stage of plant development and duration of drought. BR priming induced fewer differentially expressed genes (DEGs) than no BR priming under well-watered condition. Drought with BR priming reduced the number of DEGs than drought only. These DEGs were enriched in varied gene ontologies and metabolism pathways. Downregulation of DEGs involved in both light perceiving and photosynthesis in leaves is consistent with low parameters of photosynthesis. Optimal BR priming partially rescued the levels of growth promoting auxin and gibberellin which were largely reduced by drought, and increased levels of defense associated abscisic acid and salicylic acid after long-term drought. BR priming induced many DEGs which function as kinase or transcription factor for signal cascade under drought. We proposed BR priming-induced regulatory responses will be memorized and recalled for fast adaptation in later drought stress. These results provide physiological and regulatory bases of effects of seed priming with BR, which can help to guide the framing improvement under drought stress.
PMID: 32796553
Plant Physiol Biochem , IF:3.72 , 2020 Aug , V155 : P512-522 doi: 10.1016/j.plaphy.2020.08.001
Transcriptional analysis reveals potential genes and regulatory networks involved in salicylic acid-induced flowering in duckweed (Lemna gibba).
Institute of Tropical Bioscience and Biotechnology, MOA Key Laboratory of Tropical Crops Biology and Genetic Resources, Hainan Bioenergy Center, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China; Hainan Key Laboratory for Protection and Utilization of Tropical Bioresources, Hainan Institute for Tropical Agricultural Resources, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China. Electronic address: fulili@itbb.org.cn.; Institute of Tropical Bioscience and Biotechnology, MOA Key Laboratory of Tropical Crops Biology and Genetic Resources, Hainan Bioenergy Center, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China; Hainan Key Laboratory for Protection and Utilization of Tropical Bioresources, Hainan Institute for Tropical Agricultural Resources, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China. Electronic address: tandeguan@itbb.org.cn.; Institute of Tropical Bioscience and Biotechnology, MOA Key Laboratory of Tropical Crops Biology and Genetic Resources, Hainan Bioenergy Center, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China; Hainan Key Laboratory for Protection and Utilization of Tropical Bioresources, Hainan Institute for Tropical Agricultural Resources, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China. Electronic address: sunxuepiao@itbb.org.cn.; Institute of Tropical Bioscience and Biotechnology, MOA Key Laboratory of Tropical Crops Biology and Genetic Resources, Hainan Bioenergy Center, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China; Hainan Key Laboratory for Protection and Utilization of Tropical Bioresources, Hainan Institute for Tropical Agricultural Resources, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China. Electronic address: dingzehong@itbb.org.cn.; Institute of Tropical Bioscience and Biotechnology, MOA Key Laboratory of Tropical Crops Biology and Genetic Resources, Hainan Bioenergy Center, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China; Hainan Key Laboratory for Protection and Utilization of Tropical Bioresources, Hainan Institute for Tropical Agricultural Resources, Chinese Academy of Tropical Agricultural Sciences, Xueyuan Road 4, Haikou, 571101, China. Electronic address: zhangjiaming@itbb.org.cn.
Duckweed is a simple aquatic floating plant having great potential in sewage treatment and bioenergy production. Duckweed rarely flowers in nature, which greatly limits its germplasm collection, conservation, and heterosis usage. Salicylic acid (SA) can efficiently induce flowering of duckweed (e.g., Lemna gibba); however, the related genes and regulatory networks remain unclear. In this work, we demonstrated that L. gibba flowering induced by SA was photoperiod-dependent, stress-involved, and abscisic acid (ABA)-disrupted. Totally 202, 78, and 413 differentially expressed (DE) genes were up-regulated, while 429, 72, and 307 were down-regulated at flower induction, flower initiation, and flowering stages, respectively. At the flower induction stage, the down-regulated genes were mainly involved in cell wall, auxin and ABA, light reaction, and abiotic stress, while the up-regulated genes were involved in development, brassinosteroid, major CHO metabolism, and redox. At the flower initiation stage, the down-regulated genes were enriched in light reaction and lipid metabolism, whereas the up-regulated genes were enriched in starch degradation and Ca(2+) signaling. At the flowering stage, the down-regulated genes were significantly enriched in photosynthesis, gibberellic acid, starch synthesis, nitrogen metabolism, and redox, while the up-regulated genes were enriched in cell wall, jasmonic acid, secondary metabolism, and Ca(2+) signaling. Besides, 46 transcription factors and 13 flowering-related DE genes were identified. Finally, a possible floral pathway, where LgTEM1, LgSVP, and LgFT1 might play critical roles in SA-induced flowering in L. gibba, was discussed. These findings provide a useful foundation for further investigation of genes and regulatory networks of SA-induced flowering in duckweed.
PMID: 32836197
Plant Mol Biol , IF:3.302 , 2020 Aug doi: 10.1007/s11103-020-01033-8
Integrative omics approaches revealed a crosstalk among phytohormones during tuberous root development in cassava.
RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan. yoshinori.utsumi@riken.jp.; RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan.; RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.; Faculty of Agriculture, Yamagata University, Tsuruoka, Japan.; Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan.; Graduate School of Pharmaceutical Sciences, Chiba University, Chiba, Chiba, 260-8675, Japan.; Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601, Japan.; Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.; RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa, 230-0045, Japan. motoaki.seki@riken.jp.; RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan. motoaki.seki@riken.jp.; Kihara Institute for Biological Research, Yokohama City University, 641-12 Maioka-cho, Totsuka-ku, Yokohama, Kanagawa, 244-0813, Japan. motoaki.seki@riken.jp.
KEY MESSAGE: Integrative omics approaches revealed a crosstalk among phytohormones during tuberous root development in cassava. Tuberous root formation is a complex process consisting of phase changes as well as cell division and elongation for radial growth. We performed an integrated analysis to clarify the relationships among metabolites, phytohormones, and gene transcription during tuberous root formation in cassava (Manihot esculenta Crantz). We also confirmed the effects of the auxin (AUX), cytokinin (CK), abscisic acid (ABA), jasmonic acid (JA), gibberellin (GA), brassinosteroid (BR), salicylic acid, and indole-3-acetic acid conjugated with aspartic acid on tuberous root development. An integrated analysis of metabolites and gene expression indicated the expression levels of several genes encoding enzymes involved in starch biosynthesis and sucrose metabolism are up-regulated during tuberous root development, which is consistent with the accumulation of starch, sugar phosphates, and nucleotides. An integrated analysis of phytohormones and gene transcripts revealed a relationship among AUX signaling, CK signaling, and BR signaling, with AUX, CK, and BR inducing tuberous root development. In contrast, ABA and JA inhibited tuberous root development. These phenomena might represent the differences between stem tubers (e.g., potato) and root tubers (e.g., cassava). On the basis of these results, a phytohormonal regulatory model for tuberous root development was constructed. This model may be useful for future phytohormonal studies involving cassava.
PMID: 32757126
Biochem Biophys Res Commun , IF:2.985 , 2020 Aug , V529 (1) : P91-96 doi: 10.1016/j.bbrc.2020.05.216
Obtusifoliol 14alpha-demethylase OsCYP51G1 is involved in phytosterol synthesis and affects pollen and seed development.
Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China; University of Chinese Academy of Sciences, Beijing, China.; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China.; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China. Electronic address: zhangmy@scbg.ac.cn.; Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China; Center of Economic Botany, Core Botanical Gardens, Chinese Academy of Sciences, Guangzhou, China. Electronic address: xiakuaifei@scbg.ac.cn.
As structural components of biological membranes, phytosterols are essential not only for a variety of cellular functions but are also precursors for brassinosteroid (BR) biosynthesis. Plant CYP51 is the oldest and most conserved obtusifoliol 14alpha-demethylase in eukaryotes and is an essential component of the sterol biosynthesis pathway. However, little is known about rice (Oryza sativa L.) CYP51G1. In this study, we showed that rice OsCYP51G1 shared high homology with obtusifoliol 14alpha-demethylase and OsCYP51G1 was strongly expressed in most of rice organs. Subcellular localization analysis indicated that OsCYP51G1 was localized to the endoplasmic reticulum. Knockdown and knockout of OsCYP51G1 resulted in delayed flowering, impaired membrane integrity, abnormal pollen, and reduced grain yield, whereas OsCYP51G1 overexpression led to increased grain yield. Knockdown of OsCYP51G1 also reduced the levels of end-products (sitosterol and stigmasterol) and increased those of upstream intermediates (24-methylene-cycloartenol and cycloeucalenol) of the OsCYP51G1-mediated sterol biosynthesis step. In contrast, overexpression of OsCYP51G1 increased the sitosterol and stigmasterol content and reduced that of cycloeucalenol. However, knockdown of OsCYP51G1 by RNAi did not elicit these BR deficiency-related phenotypes, such as dwarfism, erect leaves and small seeds, nor was the leaf lamina angle sensitive to brassinolide treatment. These results revealed that rice OsCYP15G1 encodes an obtusifoliol 14alpha-demethylase for the phytosterols biosynthesis and possible without affecting the biosynthesis of downstream BRs, which was different from its homolog, OsCYP51G3.
PMID: 32560825
Biochemistry , IF:2.865 , 2020 Aug , V59 (32) : P2986-2997 doi: 10.1021/acs.biochem.0c00424
Barley "uzu" and Wheat "uzu-like" Brassinosteroid Receptor BRI1 Kinase Domain Variations Modify Phosphorylation Activity In Vitro.
National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada.; National Research Council of Canada, 110 Gymnasium Place, Saskatoon, SK S7N 0W9, Canada.
Brassinosteroid insensitive1 (BRI1), a leucine-rich repeat receptor kinase, is responsible for the perception of the brassinosteroid (BR) phytohormone in plants. While recent evidence has implicated a naturally occurring Hordeum vulgare V. (barley) HvBRI1 kinase domain (KD) variant (H857R; "uzu" variation) in increased fungal disease resistance, the impact of the variation on receptor function and thus the mechanism by which disease resistance might be imparted remain enigmatic. Here, the functional implications of the uzu variation as well as the effects of newly identified naturally occurring Triticum aestivum L. (wheat) TaBRI1-KD variants are investigated. Recombinantly produced KDs of wild-type (WT) and uzu HvBRI1 were assessed for phosphorylation activity in vitro, yielding WT KM and VMAX values similar to those of other reports, but the uzu variation delayed saturation and reduced turnover levels. In silico modeling of the H857R variation showed it to be surface-exposed and distal from the catalytic site. Further evaluation of three naturally occurring wheat TaBRI1 variants, A907T, A970V, and G1019R (barley numbering) identified in the A, B, and D subgenomic genes, respectively, highlighted a significant loss of activity for A907T. A907T is located on the same surface as the H857R variation and a negative regulatory phosphorylation site (T982) in Arabidopsis thaliana BRI1. A fourth variation, T1031A (barley numbering), unique to both subgenomic A proteins and localized to the BKI1 binding site, also decreased activity. The outcomes are discussed with respect to the predicted structural contexts of the variations and their implications with respect to mechanisms of action.
PMID: 32786402