Mol Plant , IF:13.164 , 2021 Jun , V14 (6) : P949-962 doi: 10.1016/j.molp.2021.03.011
A crosstalk between auxin and brassinosteroid regulates leaf shape by modulating growth anisotropy.
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, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, 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, Beijing 100101, China.; Beijing International Center for Mathematical Research, Peking University, Beijing 100871, China.; Key Laboratory of Microgravity (National Microgravity Laboratory), Center of Biomechanics and Bioengineering, and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China; School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China.; Beijing International Center for Mathematical Research, Peking University, Beijing 100871, China. Electronic address: zhangl@math.pku.edu.cn.; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: yingwang@ucas.edu.cn.; 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, Beijing 100101, China; College of Life Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: yljiao@genetics.ac.cn.
Leaf shape is highly variable within and among plant species, ranging from slender to oval shaped. This is largely determined by the proximodistal axis of growth. However, little is known about how proximal-distal growth is controlled to determine leaf shape. Here, we show that Arabidopsis leaf and sepal proximodistal growth is tuned by two phytohormones. Two class A AUXIN RESPONSE FACTORs (ARFs), ARF6 and ARF8, activate the transcription of DWARF4, which encodes a key brassinosteroid (BR) biosynthetic enzyme. At the cellular level, the phytohormones promote more directional cell expansion along the proximodistal axis, as well as final cell sizes. BRs promote the demethyl-esterification of cell wall pectins, leading to isotropic in-plane cell wall loosening. Notably, numerical simulation showed that isotropic cell wall loosening could lead to directional cell and organ growth along the proximodistal axis. Taken together, we show that auxin acts through biosynthesis of BRs to determine cell wall mechanics and directional cell growth to generate leaves of variable roundness.
PMID: 33722761
Plant Cell , IF:11.277 , 2021 Jun doi: 10.1093/plcell/koab165
HBI Transcription Factor-Mediated ROS Homeostasis Regulates Nitrate Signal Transduction.
The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, China.; College of Agriculture, Shanxi Agricultural University, Taigu, 030801, China.; Crop Research Institute, Shandong Academy of Agricultural Sciences, Jinan, 250100, China.; State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an, 271018, China.; School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China.; School of Life Sciences and Division of Molecular & Cell Biophysics, Hefei National Science Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, 230027, China.
Nitrate is both an important nutrient and a critical signaling molecule that regulates plant metabolism, growth, and development. Although several components of the nitrate signaling pathway have been identified, the molecular mechanism of nitrate signaling remains unclear. Here, we showed that the growth-related transcription factors HOMOLOG OF BRASSINOSTEROID ENHANCED EXPRESSION2 INTERACTING WITH IBH1 (HBI1) and its three closest homologs (HBIs) positively regulate nitrate signaling in Arabidopsis thaliana. HBI1 is rapidly induced by nitrate through NLP6 and NLP7, which are master regulators of nitrate signaling. Mutations in HBIs result in the reduced effects of nitrate on plant growth and approximately 22% nitrate-responsive genes no longer to be regulated by nitrate. HBIs increase the expression levels of a set of antioxidant genes to reduce the accumulation of reactive oxygen species (ROS) in plants. Nitrate treatment induces the nuclear localization of NLP7, whereas such promoting effects of nitrate are significantly impaired in the hbi-q and cat2 cat3 mutants, which accumulate high levels of H2O2. These results demonstrate that HBI-mediated ROS homeostasis regulates nitrate signal transduction through modulating the nucleocytoplasmic shuttling of NLP7. Overall, our findings reveal that nitrate treatment reduces the accumulation of H2O2, and H2O2 inhibits nitrate signaling, thereby forming a feedback regulatory loop to regulate plant growth and development.
PMID: 34129038
Plant Cell , IF:11.277 , 2021 Jun doi: 10.1093/plcell/koab127
Corrigendum to: Plant U-Box 40 mediates degradation of the brassinosteroid-responsive transcription factor BZR1 in Arabidopsis roots.
PMID: 34097072
New Phytol , IF:10.151 , 2021 Jul , V231 (2) : P695-712 doi: 10.1111/nph.17403
BRASSINOSTEROID-SIGNALING KINASE 1 phosphorylating CALCIUM/CALMODULIN-DEPENDENT PROTEIN KINASE functions in drought tolerance in maize.
College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China.; Institute of Food Crops, Provincial Key Laboratory of Agrobiology, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China.; National Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China.
Drought stress seriously limits crop productivity. Although studies have been carried out, it is still largely unknown how plants respond to drought stress. Here we find that drought treatment can enhance the phosphorylation activity of brassinosteroid-signaling kinase 1 (ZmBSK1) in maize (Zea mays). Our genetic studies reveal that ZmBSK1 positively affects drought tolerance in maize plants. ZmBSK1 localizes in plasma membrane, interacts with calcium/calmodulin (Ca(2+) /CaM)-dependent protein kinase (ZmCCaMK), and phosphorylates ZmCCaMK. Ser-67 is a crucial phosphorylation site of ZmCCaMK by ZmBSK1. Drought stress enhances not only the interaction between ZmBSK1 and ZmCCaMK but also the phosphorylation of Ser-67 in ZmCCaMK by ZmBSK1. Furthermore, Ser-67 phosphorylation in ZmCCaMK regulates its Ca(2+) /CaM binding, autophosphorylation and transphosphorylation activity, and positively affects its function in drought tolerance in maize. Our results reveal an important role for ZmBSK1 in drought tolerance and suggest a direct regulatory mode of ZmBSK1 phosphorylating ZmCCaMK.
PMID: 33864702
Environ Pollut , IF:8.071 , 2021 Jul , V280 : P116992 doi: 10.1016/j.envpol.2021.116992
Exogenous 24-Epibrassinolide stimulates root protection, and leaf antioxidant enzymes in lead stressed rice plants: Central roles to minimize Pb content and oxidative stress.
Nucleo de Pesquisa Vegetal Basica e Aplicada, Universidade Federal Rural da Amazonia Paragominas, Para, Brazil.; Centro de Ciencias Naturais e Humanas, Universidade Federal Do ABC, Santo Andre, Sao Paulo, Brazil.; Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia.; Botany and Microbiology Department, College of Science, King Saud University, Riyadh, Saudi Arabia; Department of Botany, S.P. College Srinagar, Jammu and Kashmir, India.; Nucleo de Pesquisa Vegetal Basica e Aplicada, Universidade Federal Rural da Amazonia Paragominas, Para, Brazil. Electronic address: allanllobato@yahoo.com.br.
Lead (Pb) is an environmental pollutant that negatively affects rice plants, causing damage to the root system and chloroplast structures, as well as reducing growth. 24-Epibrasnolide (EBR) is a plant growth regulator with a high capacity to modulate antioxidant metabolism. The objective of this research was to investigate whether exogenous EBR application can mitigate oxidative damage in Pb-stressed rice plants, measure anatomical structures and evaluate physiological and biochemical responses connected with redox metabolism. The experiment was randomized with four treatments, including two lead treatments (0 and 200 muM PbCl2, described as - Pb and + Pb, respectively) and two treatments with brassinosteroid (0 and 100 nM EBR, described as - EBR and + EBR, respectively). The results revealed that plants exposed to Pb suffered significant disturbances, but the EBR alleviated the negative interferences, as confirmed by the improvements in the root structures and antioxidant system. This steroid stimulated the root structures, increasing the epidermis thickness (26%) and aerenchyma area (50%), resulting in higher protection of this tissue against Pb(2+) ions. Additionally, EBR promoted significant increases in superoxide dismutase (26%), catalase (24%), ascorbate peroxidase (54%) and peroxidase (63%) enzymes, reducing oxidative stress on the photosynthetic machinery in Pb-stressed plants. This research proved that EBR mitigates the toxic effects generated by Pb in rice plants.
PMID: 33784567
Curr Opin Plant Biol , IF:7.834 , 2021 Jun , V63 : P102055 doi: 10.1016/j.pbi.2021.102055
Transport mechanisms of plant hormones.
School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, 69978, Israel.; School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv, 69978, Israel. Electronic address: eilonsh@tauex.tau.ac.il.
Plant growth, development, and response to the environment are mediated by a group of small signaling molecules named hormones. Plants regulate hormone response pathways at multiple levels, including biosynthesis, metabolism, perception, and signaling. In addition, plants exhibit the unique ability to spatially control hormone distribution. In recent years, multiple transporters have been identified for most of the plant hormones. Here we present an updated snapshot of the known transporters for the hormones abscisic acid, auxin, brassinosteroid, cytokinin, ethylene, gibberellin, jasmonic acid, salicylic acid, and strigolactone. We also describe new findings regarding hormone movement and elaborate on hormone substrate specificity and possible genetic redundancy in hormone transport and distribution. Finally, we discuss subcellular, cell-to-cell, and long-distance hormone movement and local hormone sinks that trigger or prevent hormone-mediated responses.
PMID: 34102450
J Exp Bot , IF:6.992 , 2021 Jun doi: 10.1093/jxb/erab284
Brassinolide inhibits flavonoid biosynthesis and red-flesh coloration via the MdBEH2.2-MdMYB60 complex in apple.
College of Horticulture, Shandong Agricultural University, Taian, Shandong, China.
The flavonoid content, which is an important indicator of the nutritional value of fruits and vegetables, directly determines the marketability of many fruit crops, including apple (Malus domestica). Brassinosteroids (BRs) are steroid hormones that affect flavonoid biosynthesis in plants, but the underlying regulatory mechanism remains unclear. In this study, treatments with brassinolide (the most active BR) and brassinazole (a BR biosynthesis inhibitor) respectively decreased and increased the flavonoid, anthocyanin, and proanthocyanidin (PA) contents in red-fleshed apple seedlings and calli. We subsequently demonstrated that a BZR family transcription factor (TF), MdBEH2.2, participates in BR-regulated flavonoid biosynthesis. Specifically, MdBEH2.2 inhibits the accumulation of flavonoids, anthocyanins, and PAs in apple seedlings; however, a brassinazole treatment can weaken the inhibitory effect. Additionally, we confirmed that a BR-induced MYB TF, MdMYB60, interacts with MdBEH2.2. The resulting MdBEH2.2-MdMYB60 complex further enhances the inhibitory effect of MdBEH2.2 or MdMYB60 on the transcription of structural genes. These results imply that brassinolide decreases flavonoid contents through the MdBEH2.2-MdMYB60 regulatory module. Our findings further clarify the molecular mechanism mediating the regulation of flavonoid biosynthesis by BR signals in horticultural crops.
PMID: 34128531
J Exp Bot , IF:6.992 , 2021 Jun doi: 10.1093/jxb/erab260
PtBRI1.2 promotes shoot growth and wood formation through a brassinosteroid-mediated PtBZR1-PtWNDs module in poplar.
The Engineering Research Institute of Agriculture and Forestry, Ludong University, 186 Hongqizhong Road, Yantai, China.; Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, 368 Youyi Avenue, Wuhan, China.; National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai, China.; The Key Laboratory of Molecular Module-Based Breeding of High Yield and abiotic Resistant Plants in the Universities of Shandong, and Institute for Advanced Study of Coastal Ecology, Ludong University, 186 Hongqizhong Road, Yantai, China.; Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions, Institute of Tropical Bioscience and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, 4 Xueyuan Road, Haikou, China.
Brassinosteroid-insensitive-1 (BRI1) plays important roles in various signaling pathways controlling plant growth and development. However, the regulatory mechanism of BRI1 in brassinosteroid (BR)-mediated signaling for shoot growth and wood formation in woody plant is largely unknown. In this study, PtBRI1.2, a brassinosteroid-insensitive-1 gene, was overexpressed in poplar. Shoot growth and wood formation of transgenic plants were examined and the regulatory genes involved were verified. PtBRI1.2 was localized to plasma membrane, with a predominant expression in leaves. Ectopic expression of PtBRI1.2 in Arabidopsis bri1-201 and bri1-5 mutants rescued their retarded-growth phenotype. Overexpression of PtBRI1.2 in poplar promoted shoot growth and wood formation of transgenic plants. Further studies revealed that overexpression of PtBRI1.2 impelled the accumulation of PtBZR1 into the nucleus, which subsequently activated PtWNDs to up-regulate the expression of secondary cell wall biosynthesis genes involved in wood formation. Our results suggest that PtBRI1.2 plays a crucial role in regulating shoot growth and wood formation by activating BR signaling.
PMID: 34089602
J Exp Bot , IF:6.992 , 2021 Jun , V72 (13) : P4708-4720 doi: 10.1093/jxb/erab192
A transcriptional hub integrating gibberellin-brassinosteroid signals to promote seed germination in Arabidopsis.
College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, China.; Department of Plant and Soil Sciences, Kentucky Tobacco Research and Development Center, University of Kentucky, Lexington, KY, USA.; Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Science, South China Normal University, Guangzhou, China.
Seed germination is regulated by multiple phytohormones, including gibberellins (GAs) and brassinosteroids (BRs); however, the molecular mechanism underlying GA and BR co-induced seed germination is not well elucidated. We demonstrated that BRs induce seed germination through promoting testa and endosperm rupture in Arabidopsis. BRs promote cell elongation, rather than cell division, at the hypocotyl-radicle transition region of the embryonic axis during endosperm rupture. Two key basic helix-loop-helix transcription factors in the BR signaling pathway, HBI1 and BEE2, are involved in the regulation of endosperm rupture. Expression of HBI1 and BEE2 was induced in response to BR and GA treatment. In addition, HBI1- or BEE2-overexpressing Arabidopsis plants are less sensitive to the BR biosynthesis inhibitor, brassinazole, and the GA biosynthesis inhibitor, paclobutrazol. HBI1 and BEE2 promote endosperm rupture and seed germination by directly regulating the GA-Stimulated Arabidopsis 6 (GASA6) gene. Expression of GASA6 was altered in Arabidopsis overexpressing HBI1, BEE2, or SRDX-repressor forms of the two transcription factors. In addition, HBI1 interacts with BEE2 to synergistically activate GASA6 expression. Our findings define a new role for GASA6 in GA and BR signaling and reveal a regulatory module that controls GA and BR co-induced seed germination in Arabidopsis.
PMID: 33963401
Mol Plant Pathol , IF:5.663 , 2021 Jun doi: 10.1111/mpp.13098
Infection of Arabidopsis by cucumber mosaic virus triggers jasmonate-dependent resistance to aphids that relies partly on the pattern-triggered immunity factor BAK1.
Department of Plant Sciences, University of Cambridge, Cambridge, UK.; NIAB EMR, East Malling, UK.; Institute of Bioengineering, Zhejiang Sci-Tech University, Hangzhou, China.
Many aphid-vectored viruses are transmitted nonpersistently via transient attachment of virus particles to aphid mouthparts and are most effectively acquired or transmitted during brief stylet punctures of epidermal cells. In Arabidopsis thaliana, the aphid-transmitted virus cucumber mosaic virus (CMV) induces feeding deterrence against the polyphagous aphid Myzus persicae. This form of resistance inhibits prolonged phloem feeding but promotes virus acquisition by aphids because it encourages probing of plant epidermal cells. When aphids are confined on CMV-infected plants, feeding deterrence reduces their growth and reproduction. We found that CMV-induced inhibition of growth as well as CMV-induced inhibition of reproduction of M. persicae are dependent upon jasmonate-mediated signalling. BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1) is a co-receptor enabling detection of microbe-associated molecular patterns and induction of pattern-triggered immunity (PTI). In plants carrying the mutant bak1-5 allele, CMV induced inhibition of M. persicae reproduction but not inhibition of aphid growth. We conclude that in wildtype plants CMV induces two mechanisms that diminish performance of M. persicae: a jasmonate-dependent and PTI-dependent mechanism that inhibits aphid growth, and a jasmonate-dependent, PTI-independent mechanism that inhibits reproduction. The growth of two crucifer specialist aphids, Lipaphis erysimi and Brevicoryne brassicae, was not affected when confined on CMV-infected A. thaliana. However, B. brassicae reproduction was inhibited on CMV-infected plants. This suggests that in A. thaliana CMV-induced resistance to aphids, which is thought to incentivize virus vectoring, has greater effects on polyphagous than on crucifer specialist aphids.
PMID: 34156752
Mol Plant Pathol , IF:5.663 , 2021 Jul , V22 (7) : P786-799 doi: 10.1111/mpp.13062
BRASSINOSTEROID-SIGNALLING KINASES 7 and 8 associate with the FLS2 immune receptor and are required for flg22-induced PTI responses.
School of Plant Sciences and Food Security, Tel-Aviv University, Tel-Aviv, Israel.
Pattern-triggered immunity (PTI) is typically initiated in plants by recognition of pathogen- or damage-associated molecular patterns (PAMP/DAMPs) by cell surface-localized pattern recognition receptors (PRRs). Here, we investigated the role in PTI of Arabidopsis thaliana brassinosteroid-signalling kinases 7 and 8 (BSK7 and BSK8), which are members of the receptor-like cytoplasmic kinase subfamily XII. BSK7 and BSK8 localized to the plant cell periphery and interacted in yeast and in planta with FLS2, but not with other PRRs. Consistent with a role in FLS2 signalling, bsk7 and bsk8 single and bsk7,8 double mutant plants were impaired in several immune responses induced by flg22, but not by other PAMP/DAMPs. These included resistance to Pseudomonas syringae and Botrytis cinerea, reactive oxygen species accumulation, callose deposition at the cell wall, and expression of the defence-related gene PR1, but not activation of MAP kinases and expression of the FRK1 and WRKY29 genes. bsk7, bsk8, and bsk7,8 plants also displayed enhanced susceptibility to P. syringae and B. cinerea. Finally, BSK7 and BSK8 variants mutated in their myristoylation site or in the ATP-binding site failed to complement defective phenotypes of the corresponding mutants, suggesting that localization to the cell periphery and kinase activity are critical for BSK7 and BSK8 functions. Together, these findings demonstrate that BSK7 and BSK8 play a role in PTI initiated by recognition of flg22 by interacting with the FLS2 immune receptor.
PMID: 33955635
Physiol Plant , IF:4.5 , 2021 Jul , V172 (3) : P1493-1505 doi: 10.1111/ppl.13339
Two ATAF transcription factors ANAC102 and ATAF1 contribute to the suppression of cytochrome P450-mediated brassinosteroid catabolism in Arabidopsis.
Department of Crop and Soil Sciences, Washington State University, Pullman, Washington, USA.
PHYB ACTIVATION TAGGED SUPPRESSOR 1 (BAS1) and SUPPRESSOR OF PHYB-4 7 (SOB7) are two cytochrome P450 enzymes that inactivate brassinosteroids (BRs) in Arabidopsis. The NAC transcription factor (TF) ATAF2 (ANAC081) and the core circadian clock regulator CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) both suppress the expression of BAS1 and SOB7 via direct promoter binding. Additionally, BRs cause feedback suppression on ATAF2 expression. Here, we report that two ATAF-subgroup TFs, ANAC102 and ATAF1 (ANAC002), also contribute to the transcriptional suppression of BAS1 and SOB7. ANAC102 and ATAF1 gene-knockout mutants exhibit elevated expression of both BAS1 and SOB7, expanded tissue-level accumulation of their protein products and reduced hypocotyl growth in response to exogenous BR treatments. Similar to ATAF2, both ANAC102 and ATAF1 are transcriptionally suppressed by BRs and white light. Neither BAS1 nor SOB7 expression is further elevated in ATAF double or triple mutants, suggesting that the suppression effect of these three ATAFs is not additive. In addition, ATAF single, double, and triple mutants have similar levels of BR responsiveness with regard to hypocotyl elongation. ATAF2, ANAC102, ATAF1, and CCA1 physically interact with itself and each other, suggesting that they may coordinately suppress BAS1 and SOB7 expression via protein-protein interactions. Despite the absence of CCA1-binding elements in their promoters, ANAC102 and ATAF1 have similar transcript circadian oscillation patterns as that of CCA1, suggesting that these two ATAF genes may be indirectly regulated by the circadian clock.
PMID: 33491178
BMC Plant Biol , IF:4.215 , 2021 Jun , V21 (1) : P291 doi: 10.1186/s12870-021-03081-8
Evolutionary analysis and functional characterization of SiBRI1 as a Brassinosteroid receptor gene in foxtail millet.
Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaboration Innovation Center for Cell Signaling and Environmental Adaptation, Hebei Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, 050024, China.; Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China.; College of Life Sciences, Langfang Normal University, Langfang, 065000, China.; Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, China. diaoxianmin@caas.cn.; Foxtail Millet Improvement Center of China, Institute of Millet Crops, Hebei Academy of Agricultural and Forestry Science, Shijiazhuang, 050031, China. diaoxianmin@caas.cn.; Ministry of Education Key Laboratory of Molecular and Cellular Biology, Hebei Collaboration Innovation Center for Cell Signaling and Environmental Adaptation, Hebei Key Laboratory of Molecular and Cellular Biology, College of Life Sciences, Hebei Normal University, Shijiazhuang, Hebei, 050024, China. zhangbw@hebtu.edu.cn.
Brassinosteroids (BRs) play important roles in plant growth and development. Although BR receptors have been intensively studied in Arabidopsis, those in foxtail millet remain largely unknown. Here, we show that the BR signaling function of BRASSINOSTEROID INSENSITIVE 1 (BRI1) is conserved between Arabidopsis and foxtail millet, a new model species for C4 and Panicoideae grasses. We identified four putative BR receptor genes in the foxtail millet genome: SiBRI1, SiBRI1-LIKE RECEPTOR KINASE 1 (SiBRL1), SiBRL2 and SiBRL3. Phylogenetic analysis was used to classify the BR receptors in dicots and monocots into three branches. Analysis of their expression patterns by quantitative real-time PCR (qRT-PCR) showed that these receptors were ubiquitously expressed in leaves, stems, dark-grown seedlings, roots and non-flowering spikelets. GFP fusion experiments verified that SiBRI1 localized to the cell membrane. We also explored the SiBRI1 function in Arabidopsis through complementation experiments. Ectopic overexpression of SiBRI1 in an Arabidopsis BR receptor loss-of-function mutant, bri1-116, mostly reversed the developmental defects of the mutant. When SiBRI1 was overexpressed in foxtail millet, the plants showed a drooping leaf phenotype and root development inhibition, lateral root initiation inhibition, and the expression of BR synthesis genes was inhibited. We further identified BRI1-interacting proteins by immunoprecipitation (IP)-mass spectrometry (MS). Our results not only demonstrate that SiBRI1 plays a conserved role in BR signaling in foxtail millet but also provide insight into the molecular mechanism of SiBRI1.
PMID: 34167462
BMC Plant Biol , IF:4.215 , 2021 Jun , V21 (1) : P268 doi: 10.1186/s12870-021-03045-y
BRS1 mediates plant redox regulation and cold responses.
State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China.; State Key Laboratory of Crop Stress Biology for Arid Areas, College of Agronomy, Northwest A&F University, Yangling, 712100, Shaanxi, China. xushb@nwsuaf.edu.cn.
BACKGROUND: Brassinosteroid-insensitive 1 suppressor 1 (BRS1) is a serine carboxypeptidase that mediates brassinosteroid signaling and participates in multiple developmental processes in Arabidopsis. However, little is known about the precise role of BRS1 in this context. RESULTS: In this study, we analyzed transcriptional and proteomic profiles of Arabidopsis seedlings overexpressing BRS1 and found that this gene was involved in both cold stress responses and redox regulation. Further proteomic evidence showed that BRS1 regulated cell redox by indirectly interacting with cytosolic NADP + -dependent isocitrate dehydrogenase (cICDH). One novel alternative splice form of BRS1 was identified in over-expression mutants brs1-1D, which may confer a new role in plant development and stress responses. CONCLUSIONS: This study highlights the role of BRS1 in plant redox regulation and stress responses, which extends our understanding of extracellular serine carboxypeptidases.
PMID: 34116634
BMC Plant Biol , IF:4.215 , 2021 Jun , V21 (1) : P261 doi: 10.1186/s12870-021-03013-6
Differential transcription pathways associated with rootstock-induced dwarfing in breadfruit (Artocarpus altilis) scions.
Australian Centre for Pacific Islands Research, University of the Sunshine Coast, Sippy Downs, QLD, 4556, Australia. yzhou1@usc.edu.au.; Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD, 4072, Australia. yzhou1@usc.edu.au.; Australian Centre for Pacific Islands Research, University of the Sunshine Coast, Sippy Downs, QLD, 4556, Australia.; Queensland Alliance for Agriculture and Food Innovation, University of Queensland, St Lucia, QLD, 4072, Australia.
BACKGROUND: Breadfruit (Artocarpus altilis) is a traditional staple tree crop throughout the tropics. Through interspecific grafting, a dwarf phenotype with over 50% reduction in plant height was identified when marang (Artocarpus odoratissimus) rootstocks were used. However, the molecular mechanism underlying the rootstock-induced breadfruit dwarfing is poorly understood. RESULTS: An RNA-sequencing study of breadfruit scions at 22 months after grafting identified 5409 differentially expressed genes (DEGs) of which 2069 were upregulated and 3339 were downregulated in scion stems on marang rootstocks compared to those on self-graft. The DEGs were predominantly enriched for biological processes involved in carbon metabolism, cell wall organization, plant hormone signal transduction and redox homeostasis. The down-regulation of genes encoding vacuolar acid invertases and alkaline/neutral invertases, was consistent with the decreased activity of both enzymes, accompanying with a higher sucrose but lower glucose and fructose levels in the tissues. Key genes of biosynthetic pathways for amino acids, lipids and cell wall were down regulated, reflecting reduction of sucrose utilisation for stem growth on dwarfing rootstocks. Genes encoding sugar transporters, amino acid transporters, choline transporters, along with large number of potassium channels and aquaporin family members were down-regulated in scion stems on marang rootstocks. Lower activity of plasma membrane H(+)-ATPase, together with the predominance of genes encoding expansins, wall-associated receptor kinases and key enzymes for biosynthesis and re-modelling of cellulose, xyloglucans and pectins in down-regulated DGEs suggested impairment of cell expansion. Signalling pathways of auxin and gibberellin, along with strigolacton and brassinosteroid biosynthetic genes dominated the down-regulated DEGs. Phenylpropanoid pathway was enriched, with key lignin biosynthetic genes down-regulated, and flavonoid biosynthetic genes upregulated in scions on marang rootstocks. Signalling pathways of salicylic acid, jasmonic acid, ethylene and MAPK cascade were significantly enriched in the upregulated DEGs. CONCLUSIONS: Rootstock-induced disruption in pathways regulating nutrient transport, sucrose utilisation, cell wall biosynthesis and networks of hormone transduction are proposed to impair cell expansion and stem elongation, leading to dwarf phenotype in breadfruit scions. The information provides opportunity to develop screening strategy for rootstock breeding and selection for breadfruit dwarfing.
PMID: 34090350
BMC Genomics , IF:3.969 , 2021 Jun , V22 (1) : P465 doi: 10.1186/s12864-021-07778-w
Genome-wide expression and network analyses of mutants in key brassinosteroid signaling genes.
Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.; Department of Information Technology, IDLab, imec, Ghent University, Ghent, Belgium.; Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, 430074, China.; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China.; Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium. kathleen.marchal@ugent.be.; Department of Information Technology, IDLab, imec, Ghent University, Ghent, Belgium. kathleen.marchal@ugent.be.; Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa. kathleen.marchal@ugent.be.; Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China. lijia@lzu.edu.cn.
BACKGROUND: Brassinosteroid (BR) signaling regulates plant growth and development in concert with other signaling pathways. Although many genes have been identified that play a role in BR signaling, the biological and functional consequences of disrupting those key BR genes still require detailed investigation. RESULTS: Here we performed phenotypic and transcriptomic comparisons of A. thaliana lines carrying a loss-of-function mutation in BRI1 gene, bri1-5, that exhibits a dwarf phenotype and its three activation-tag suppressor lines that were able to partially revert the bri1-5 mutant phenotype to a WS2 phenotype, namely bri1-5/bri1-1D, bri1-5/brs1-1D, and bri1-5/bak1-1D. From the three investigated bri1-5 suppressors, bri1-5/bak1-1D was the most effective suppressor at the transcriptional level. All three bri1-5 suppressors showed altered expression of the genes in the abscisic acid (ABA signaling) pathway, indicating that ABA likely contributes to the partial recovery of the wild-type phenotype in these bri1-5 suppressors. Network analysis revealed crosstalk between BR and other phytohormone signaling pathways, suggesting that interference with one hormone signaling pathway affects other hormone signaling pathways. In addition, differential expression analysis suggested the existence of a strong negative feedback from BR signaling on BR biosynthesis and also predicted that BRS1, rather than being directly involved in signaling, might be responsible for providing an optimal environment for the interaction between BRI1 and its ligand. CONCLUSIONS: Our study provides insights into the molecular mechanisms and functions of key brassinosteroid (BR) signaling genes, especially BRS1.
PMID: 34157989
Plant Direct , IF:3.038 , 2021 Jun , V5 (6) : Pe00326 doi: 10.1002/pld3.326
slim shady is a novel allele of PHYTOCHROME B present in the T-DNA line SALK_015201.
Department of Genetics Development and Cell Biology Iowa State University Ames IA USA.; Center for Plant Biology Purdue University West Lafayett IN USA.; Department of Horticulture and Landscape Architecture Purdue University West Lafayett IN USA.; Department of Plant Pathology and Microbiology Iowa State University Ames IA USA.; Department of Biochemistry Purdue University West Lafayett IN USA.
Auxin is a hormone that is required for hypocotyl elongation during seedling development. In response to auxin, rapid changes in transcript and protein abundance occur in hypocotyls, and some auxin responsive gene expression is linked to hypocotyl growth. To functionally validate proteomic studies, a reverse genetics screen was performed on mutants in auxin-regulated proteins to identify novel regulators of plant growth. This uncovered a long hypocotyl mutant, which we called slim shady, in an annotated insertion line in IMMUNOREGULATORY RNA-BINDING PROTEIN (IRR). Overexpression of the IRR gene failed to rescue the slim shady phenotype and characterization of a second T-DNA allele of IRR found that it had a wild-type (WT) hypocotyl length. The slim shady mutant has an elevated expression of numerous genes associated with the brassinosteroid-auxin-phytochrome (BAP) regulatory module compared to WT, including transcription factors that regulate brassinosteroid, auxin, and phytochrome pathways. Additionally, slim shady seedlings fail to exhibit a strong transcriptional response to auxin. Using whole genome sequence data and genetic complementation analysis with SALK_015201C, we determined that a novel single nucleotide polymorphism in PHYTOCHROME B was responsible for the slim shady phenotype. This is predicted to induce a frameshift and premature stop codon at leucine 1125, within the histidine kinase-related domain of the carboxy terminus of PHYB, which is required for phytochrome signaling and function. Genetic complementation analyses with phyb-9 confirmed that slim shady is a mutant allele of PHYB. This study advances our understanding of the molecular mechanisms in seedling development, by furthering our understanding of how light signaling is linked to auxin-dependent cell elongation. Furthermore, this study highlights the importance of confirming the genetic identity of research material before attributing phenotypes to known mutations sourced from T-DNA stocks.
PMID: 34136747