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Dun EA, Brewer PB, Gillam EMJ, Beveridge CA. Strigolactones and Shoot Branching: What Is the Real Hormone and How Does It Work? PLANT & CELL PHYSIOLOGY 2023; 64:967-983. [PMID: 37526426 PMCID: PMC10504579 DOI: 10.1093/pcp/pcad088] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 07/26/2023] [Accepted: 08/01/2023] [Indexed: 08/02/2023]
Abstract
There have been substantial advances in our understanding of many aspects of strigolactone regulation of branching since the discovery of strigolactones as phytohormones. These include further insights into the network of phytohormones and other signals that regulate branching, as well as deep insights into strigolactone biosynthesis, metabolism, transport, perception and downstream signaling. In this review, we provide an update on recent advances in our understanding of how the strigolactone pathway co-ordinately and dynamically regulates bud outgrowth and pose some important outstanding questions that are yet to be resolved.
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Affiliation(s)
- Elizabeth A Dun
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, St Lucia, QLD 4072, Australia
- School of Agriculture and Food Sustainability, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Philip B Brewer
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, St Lucia, QLD 4072, Australia
- Waite Research Institute, School of Agriculture Food & Wine, The University of Adelaide, Adelaide, SA 5064, Australia
| | - Elizabeth M J Gillam
- School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD 4072, Australia
| | - Christine A Beveridge
- ARC Centre of Excellence for Plant Success in Nature and Agriculture, The University of Queensland, St Lucia, QLD 4072, Australia
- School of Agriculture and Food Sustainability, The University of Queensland, St Lucia, QLD 4072, Australia
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2
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Veerabagu M, van der Schoot C, Turečková V, Tarkowská D, Strnad M, Rinne PLH. Light on perenniality: Para-dormancy is based on ABA-GA antagonism and endo-dormancy on the shutdown of GA biosynthesis. PLANT, CELL & ENVIRONMENT 2023; 46:1785-1804. [PMID: 36760106 DOI: 10.1111/pce.14562] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 01/23/2023] [Accepted: 02/07/2023] [Indexed: 05/04/2023]
Abstract
Perennial para- and endo-dormancy are seasonally separate phenomena. Whereas para-dormancy is the suppression of axillary buds (AXBs) by a growing shoot, endo-dormancy is the short-day elicited arrest of terminal and AXBs. In hybrid aspen (Populus tremula x P. tremuloides) compromising the apex releases para-dormancy, whereas endo-dormancy requires chilling. ABA and GA are implicated in both phenomena. To untangle their roles, we blocked ABA biosynthesis with fluridone (FD), which significantly reduced ABA levels, downregulated GA-deactivation genes, upregulated the major GA3ox-biosynthetic genes, and initiated branching. Comprehensive GA-metabolite analyses suggested that FD treatment shifted GA production to the non-13-hydroxylation pathway, enhancing GA4 function. Applied ABA counteracted FD effects on GA metabolism and downregulated several GA3/4 -inducible α- and γ-clade 1,3-β-glucanases that hydrolyze callose at plasmodesmata (PD), thereby enhancing PD-callose accumulation. Remarkably, ABA-deficient plants repressed GA4 biosynthesis and established endo-dormancy like controls but showed increased stress sensitivity. Repression of GA4 biosynthesis involved short-day induced DNA methylation events within the GA3ox2 promoter. In conclusion, the results cast new light on the roles of ABA and GA in dormancy cycling. In para-dormancy, PD-callose turnover is antagonized by ABA, whereas in short-day conditions, lack of GA4 biosynthesis promotes callose deposition that is structurally persistent throughout endo-dormancy.
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Affiliation(s)
| | | | - Veronika Turečková
- Laboratory of Growth Regulators, Faculty of Sciences, Palacký University & Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czech Republic
| | - Danuše Tarkowská
- Laboratory of Growth Regulators, Faculty of Sciences, Palacký University & Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czech Republic
| | - Miroslav Strnad
- Laboratory of Growth Regulators, Faculty of Sciences, Palacký University & Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, Czech Republic
| | - Päivi L H Rinne
- Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
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3
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Zhang R, Dong Y, Li Y, Ren G, Chen C, Jin X. SLs signal transduction gene CsMAX2 of cucumber positively regulated to salt, drought and ABA stress in Arabidopsis thaliana L. Gene 2023; 864:147282. [PMID: 36822526 DOI: 10.1016/j.gene.2023.147282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 01/09/2023] [Accepted: 02/08/2023] [Indexed: 02/23/2023]
Abstract
Recent studies have demonstrated that strigolactones (SLs) participate in the regulation of stress adaptation, however, the mechanisms remain elusive. MAX2 (MORE AXILLARY GROWTH2) is the key gene in the signal transduction pathway of SLs. This study aimed to clone and functionally characterize the CsMAX2 gene of cucumber in Arabidopsis. The results showed that the expression levels of the CsMAX2 gene changed significantly after salt, drought, and ABA stresses in cucumber. Moreover, the overexpression of CsMAX2 promoted stress tolerance and increased the germination rate and root length of Arabidopsis thaliana. Meanwhile, the content of chlorophyll increased and malondialdehyde decreased in CsMAX2 OE lines under salt and drought stresses. Additionally, the expression levels of stress-related marker genes, especially AREB1 and COR15A, were significantly upregulated under salt stress, while the expression levels of all genes were upregulated under drought stress, except ABI4 and ABI5 genes. The level of NCED3 continued to rise under both salt and drought stresses. In addition, D10 and D27 gene expression level also showed a continuous increase under ABA stress. The result suggested the interaction between SL and ABA in the process of adapting to stress. Overall, CsMAX2 could positively regulate salt, drought, and ABA stress resistance, and this process correlated with ABA transduction.
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Affiliation(s)
- Runming Zhang
- College of Life Science and Technology, Harbin Normal University, Harbin, China
| | - Yanlong Dong
- College of Life Science and Technology, Harbin Normal University, Harbin, China; Horticulture Branch, Heilongjiang Academy of Agricultural Sciences, Harbin, China
| | - Yuanyuan Li
- College of Life Science and Technology, Harbin Normal University, Harbin, China
| | - Guangyue Ren
- College of Life Science and Technology, Harbin Normal University, Harbin, China
| | - Chao Chen
- College of Life Science and Technology, Harbin Normal University, Harbin, China
| | - Xiaoxia Jin
- College of Life Science and Technology, Harbin Normal University, Harbin, China.
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4
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Singh RK, Bhalerao RP, Maurya JP. When to branch: seasonal control of shoot architecture in trees. FEBS J 2022; 289:8062-8070. [PMID: 34652884 DOI: 10.1111/febs.16227] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/07/2021] [Accepted: 10/13/2021] [Indexed: 01/14/2023]
Abstract
Long-lived perennial plants optimize their shoot architecture by responding to seasonal cues. The main strategy used by plants of temperate and boreal regions with respect to surviving the extremely unfavourable conditions of winter comprises the protection of their apical and lateral meristematic tissues. This involves myriads of transcriptional, translational and metabolic changes in the plants because shoot architecture is controlled by multiple pathways that regulate processes such as bud formation and flowering, small RNAs, environmental factors (especially light quality, photoperiod and temperature), hormones, and sugars. Recent studies have begun to reveal how these pathways are recruited for the seasonal adaptation and regulation of shoot architecture in perennial plants, including the role of a regulatory module consisting of antagonistic players terminal flower 1 (TFL1) and like-ap1 (LAP1) in the hybrid aspen. Here, we review recent progress in our understanding of the genetic control of shoot architecture in perennials compared to in annuals.
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Affiliation(s)
- Rajesh Kumar Singh
- Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh, India
| | - Rishikesh P Bhalerao
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Jay P Maurya
- Department of Botany, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India
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5
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Yang L, Zhu S, Xu J. Roles of auxin in the inhibition of shoot branching in 'Dugan' fir. TREE PHYSIOLOGY 2022; 42:1411-1431. [PMID: 35088089 DOI: 10.1093/treephys/tpac008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 01/25/2022] [Indexed: 06/14/2023]
Abstract
Shoot branching substantially impacts vegetative and reproductive growth as well as wood characteristics in perennial woody species by shaping the shoot system architecture. Although plant hormones have been shown to play a fundamental role in shoot branching in annual species, their corresponding actions in perennial woody plants are largely unknown, in part due to the lack of branching mutants. Here, we demonstrated the role of plant hormones in bud dormancy transition toward activation and outgrowth in woody plants by comparing the physiological and molecular changes in the apical shoot stems of 'Yangkou' 020 fir and 'Dugan' fir, two Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) clones with normal and completely abolished branching phenotypes, respectively. Our studies showed that the defect in bud outgrowth was the cause of failed shoot branching in 'Dugan' fir whereas apically derived signals acted as triggers of this ectopic bud activity. Further studies indicated that auxin played a key role in inhibiting bud outgrowth in 'Dugan' fir. During bud dormancy release, the differential auxin resistant 1/Like AUX1 (AUX1/LAX) and PIN-formed (PIN) activity resulted in an ectopic auxin/indole-3-acetic acid (IAA) accumulation in the apical shoot stem of 'Dugan' fir, which could inhibit the cell cycle in the axillary meristem by decreasing cytokinin (CK) biosynthesis but increasing abscisic acid (ABA) production and response through the signaling pathway. In contrast, during bud activation and outgrowth, the striking increase in auxin biosynthesis and PIN activity in the shoot tip of 'Dugan' fir may trigger the correlative inhibition of axillary buds by modulating the polar auxin transport stream (PATS) and connective auxin transport (CAT) in shoots, and by influencing the biosynthesis of secondary messengers, including CK, gibberellin (GA) and ABA, thereby inducing the paradormancy of axillary buds in 'Dugan' fir by apical dominance under favorable conditions. The findings of this study provide important insights into the roles of plant hormones in bud outgrowth control in perennial woody plants.
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Affiliation(s)
- Liwei Yang
- Department of Forest Genetics & Biotechnology, Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education, Co-innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, No.159 Longpan Road, Nanjing, Jiangsu 210037, China
| | - Sheng Zhu
- Department of Forest Genetics & Biotechnology, Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education, Co-innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, No.159 Longpan Road, Nanjing, Jiangsu 210037, China
- Department of Molecular Biology and Biochemistry, College of Biology and Environment, Nanjing Forestry University, No.159 Longpan Road, Nanjing, Jiangsu 210037, China
| | - Jin Xu
- Department of Forest Genetics & Biotechnology, Key Laboratory of Forest Genetics & Biotechnology of Ministry of Education, Co-innovation Center for Sustainable Forestry in Southern China, College of Forestry, Nanjing Forestry University, No.159 Longpan Road, Nanjing, Jiangsu 210037, China
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Yang R, Liu W, Sun Y, Sun Z, Wu Z, Wang Y, Wang M, Wang H, Bai S, Fu C. LATERAL BRANCHING OXIDOREDUCTASE, one novel target gene of Squamosa Promoter Binding Protein-like 2, regulates tillering in switchgrass. THE NEW PHYTOLOGIST 2022; 235:563-575. [PMID: 35383390 PMCID: PMC9321131 DOI: 10.1111/nph.18140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 03/29/2022] [Indexed: 06/14/2023]
Abstract
Strigolactones (SLs) play a critical role in regulating plant tiller number. LATERAL BRANCHING OXIDOREDUCTASE (LBO) encodes an important late-acting enzyme for SL biosynthesis and regulates shoot branching in Arabidopsis. However, little is known about the function of LBO in monocots including switchgrass (Panicum virgatum L.), a dual-purpose fodder and biofuel crop. We studied the function of PvLBO via the genetic manipulation of its expression levels in both the wild-type and miR156 overexpressing (miR156OE ) switchgrass. Co-expression analysis, quantitative real-time polymerase chain reaction (qRT-PCR), transient dual luciferase assay, and chromatin immunoprecipitation-qPCR were all used to determine the activation of PvLBO by miR156-targeted Squamosa Promoter Binding Protein-like 2 (PvSPL2) in regulating tillering of switchgrass. PvLBOtranscripts dramatically declined in miR156OE transgenic switchgrass, and the overexpression of PvLBO in the miR156OE transgenic line produce fewer tillers than the control. Furthermore, we found that PvSPL2 can directly bind to the promoter of PvLBO and activate its transcription, suggesting that PvLBO is a novel downstream gene of PvSPL2. We propose that PvLBO functions as an SL biosynthetic gene to mediate tillering and acts as an important downstream factor in the crosstalk between the SL biosynthetic pathway and the miR156-SPL module in switchgrass.
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Affiliation(s)
- Ruijuan Yang
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
- University of Chinese Academy of SciencesBeijing100049China
| | - Wenwen Liu
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
| | - Ying Sun
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
| | - Zhichao Sun
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
| | - Zhenying Wu
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
- University of Chinese Academy of SciencesBeijing100049China
| | - Yamei Wang
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
| | - Mengqi Wang
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
| | - Honglun Wang
- CAS Key Laboratory of Tibetan Medicine ResearchNorthwest Institute of Plateau BiologyChinese Academy of SciencesXining810008China
| | - Shiqie Bai
- Sichuan Academy of Grassland ScienceChengdu611731China
| | - Chunxiang Fu
- Shandong Provincial Key Laboratory of Energy Genetics and CAS Key Laboratory of BiofuelsQingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao266101China
- University of Chinese Academy of SciencesBeijing100049China
- CAS Key Laboratory of Tibetan Medicine ResearchNorthwest Institute of Plateau BiologyChinese Academy of SciencesXining810008China
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Yi M, Yang H, Yang S, Wang J. Overexpression of SHORT-ROOT2 transcription factor enhances the outgrowth of mature axillary buds in poplar trees. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:2469-2486. [PMID: 35107566 DOI: 10.1093/jxb/erac040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
SHORT-ROOT (SHR) transcription factors play important roles in asymmetric cell division and radial patterning of Arabidopsis roots. In hybrid poplar (P. tremula × P. alba clone INRA 717-1B4), PtaSHR2 was preferentially expressed in axillary buds (AXBs) and transcriptionally up-regulated during AXB maturation and activation. Overexpression of SHR2 (PtSHR2OE) induced an enhanced outgrowth of AXBs below the bud maturation point, with a simultaneous transition of an active shoot apex into an arrested terminal bud. The larger and more mature AXBs of PtSHR2OE trees revealed altered expression of genes involved in axillary meristem initiation and bud activation, as well as a higher ratio of cytokinin to auxin. To elucidate the underlying mechanism of PtSHR2OE-induced high branching, subsequent molecular and biochemical studies showed that compared with wild-type trees, decapitation induced a quicker bud outburst in PtSHR2OE trees, which could be fully inhibited by exogenous application of auxin or cytokinin biosynthesis inhibitor, but not by N-1-naphthylphthalamic acid. Our results indicated that overexpression of PtSHR2B disturbed the internal hormonal balance in AXBs by interfering with the basipetal transport of auxin, rather than causing auxin biosynthesis deficiency or auxin insensitivity, thereby releasing mature AXBs from apical dominance and promoting their outgrowth.
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Affiliation(s)
- Minglei Yi
- School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Heyu Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Shaohui Yang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Jiehua Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, China
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Veerabagu M, Rinne PLH, Skaugen M, Paul LK, van der Schoot C. Lipid Body Dynamics in Shoot Meristems: Production, Enlargement, and Putative Organellar Interactions and Plasmodesmal Targeting. FRONTIERS IN PLANT SCIENCE 2021; 12:674031. [PMID: 34367200 PMCID: PMC8335594 DOI: 10.3389/fpls.2021.674031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 06/14/2021] [Indexed: 05/20/2023]
Abstract
Post-embryonic cells contain minute lipid bodies (LBs) that are transient, mobile, engage in organellar interactions, and target plasmodesmata (PD). While LBs can deliver γ-clade 1,3-β-glucanases to PD, the nature of other cargo is elusive. To gain insight into the poorly understood role of LBs in meristems, we investigated their dynamics by microscopy, gene expression analyzes, and proteomics. In developing buds, meristems accumulated LBs, upregulated several LB-specific OLEOSIN genes and produced OLEOSINs. During bud maturation, the major gene OLE6 was strongly downregulated, OLEOSINs disappeared from bud extracts, whereas lipid biosynthesis genes were upregulated, and LBs were enlarged. Proteomic analyses of the LB fraction of dormant buds confirmed that OLEOSINs were no longer present. Instead, we identified the LB-associated proteins CALEOSIN (CLO1), Oil Body Lipase 1 (OBL1), Lipid Droplet Interacting Protein (LDIP), Lipid Droplet Associated Protein1a/b (LDAP1a/b) and LDAP3a/b, and crucial components of the OLEOSIN-deubiquitinating and degradation machinery, such as PUX10 and CDC48A. All mRFP-tagged LDAPs localized to LBs when transiently expressed in Nicotiana benthamiana. Together with gene expression analyzes, this suggests that during bud maturation, OLEOSINs were replaced by LDIP/LDAPs at enlarging LBs. The LB fraction contained the meristem-related actin7 (ACT7), "myosin XI tail-binding" RAB GTPase C2A, an LB/PD-associated γ-clade 1,3-β-glucanase, and various organelle- and/or PD-localized proteins. The results are congruent with a model in which LBs, motorized by myosin XI-k/1/2, traffic on F-actin, transiently interact with other organelles, and deliver a diverse cargo to PD.
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Affiliation(s)
- Manikandan Veerabagu
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Päivi L. H. Rinne
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Skaugen
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Laju K. Paul
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Christiaan van der Schoot
- Faculty of Biosciences, Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
- *Correspondence: Christiaan van der Schoot
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Yang T, Lian Y, Kang J, Bian Z, Xuan L, Gao Z, Wang X, Deng J, Wang C. The SUPPRESSOR of MAX2 1 (SMAX1)-Like SMXL6, SMXL7 and SMXL8 Act as Negative Regulators in Response to Drought Stress in Arabidopsis. ACTA ACUST UNITED AC 2020; 61:1477-1492. [DOI: 10.1093/pcp/pcaa066] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/30/2020] [Indexed: 12/22/2022]
Abstract
Abstract
Drought represents a major threat to crop growth and yields. Strigolactones (SLs) contribute to regulating shoot branching by targeting the SUPPRESSOR OF MORE AXILLARY GROWTH2 (MAX2)-LIKE6 (SMXL6), SMXL7 and SMXL8 for degradation in a MAX2-dependent manner in Arabidopsis. Although SLs are implicated in plant drought response, the functions of the SMXL6, 7 and 8 in the SL-regulated plant response to drought stress have remained unclear. Here, we performed transcriptomic, physiological and biochemical analyses of smxl6, 7, 8 and max2 plants to understand the basis for SMXL6/7/8-regulated drought response. We found that three D53 (DWARF53)-Like SMXL members, SMXL6, 7 and 8, are involved in drought response as the smxl6smxl7smxl8 triple mutants showed markedly enhanced drought tolerance compared to wild type (WT). The smxl6smxl7smxl8 plants exhibited decreased leaf stomatal index, cuticular permeability and water loss, and increased anthocyanin biosynthesis during dehydration. Moreover, smxl6smxl7smxl8 were hypersensitive to ABA-induced stomatal closure and ABA responsiveness during and after germination. In addition, RNA-sequencing analysis of the leaves of the D53-like smxl mutants, SL-response max2 mutant and WT plants under normal and dehydration conditions revealed an SMXL6/7/8-mediated network controlling plant adaptation to drought stress via many stress- and/or ABA-responsive and SL-related genes. These data further provide evidence for crosstalk between ABA- and SL-dependent signaling pathways in regulating plant responses to drought. Our results demonstrate that SMXL6, 7 and 8 are vital components of SL signaling and are negatively involved in drought responses, suggesting that genetic manipulation of SMXL6/7/8-dependent SL signaling may provide novel ways to improve drought resistance.
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Affiliation(s)
- Tao Yang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yuke Lian
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jihong Kang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Zhiyuan Bian
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Lijuan Xuan
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Zhensheng Gao
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xinyu Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Jianming Deng
- State Key Laboratory of Grassland and Agro-Ecosystems, School of Life Science, Lanzhou University, Lanzhou 730000, China
| | - Chongying Wang
- Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
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Hu J, Sun S, Wang X. Regulation of Shoot Branching by Strigolactones and Brassinosteroids: Conserved and Specific Functions of Arabidopsis BES1 and Rice BZR1. MOLECULAR PLANT 2020; 13:808-810. [PMID: 32222484 DOI: 10.1016/j.molp.2020.03.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 03/17/2020] [Accepted: 03/20/2020] [Indexed: 05/21/2023]
Affiliation(s)
- Jie Hu
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475001, China
| | - Shiyong Sun
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475001, China.
| | - Xuelu Wang
- State Key Laboratory of Crop Stress Adaptation and Improvement, Henan University, Kaifeng 475001, China.
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Plant Lipid Bodies Traffic on Actin to Plasmodesmata Motorized by Myosin XIs. Int J Mol Sci 2020; 21:ijms21041422. [PMID: 32093159 PMCID: PMC7073070 DOI: 10.3390/ijms21041422] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/11/2020] [Accepted: 02/14/2020] [Indexed: 02/07/2023] Open
Abstract
Late 19th-century cytologists observed tiny oil drops in shoot parenchyma and seeds, but it was discovered only in 1972 that they were bound by a half unit-membrane. Later, it was found that lipid bodies (LBs) arise from the endoplasmic reticulum. Seeds are known to be packed with static LBs, coated with the LB-specific protein OLEOSIN. As shown here, apices of Populustremula x P. tremuloides also express OLEOSIN genes and produce potentially mobile LBs. In developing buds, PtOLEOSIN (PtOLE) genes were upregulated, especially PtOLE6, concomitant with LB accumulation. To investigate LB mobility and destinations, we transformed Arabidopsis with PtOLE6-eGFP. We found that PtOLE6-eGFP fusion protein co-localized with Nile Red-stained LBs in all cell types. Moreover, PtOLE6-eGFP-tagged LBs targeted plasmodesmata, identified by the callose marker aniline blue. Pharmacological experiments with brefeldin, cytochalasin D, and oryzalin showed that LB-trafficking requires F-actin, implying involvement of myosin motors. In a triple myosin-XI knockout (xi-k/1/2), transformed with PtOLE6-eGFP, trafficking of PtOLE6-eGFP-tagged LBs was severely impaired, confirming that they move on F-actin, motorized by myosin XIs. The data reveal that LBs and OLEOSINs both function in proliferating apices and buds, and that directional trafficking of LBs to plasmodesmata requires the actomyosin system.
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Katyayini NU, Rinne PLH, Tarkowská D, Strnad M, van der Schoot C. Dual Role of Gibberellin in Perennial Shoot Branching: Inhibition and Activation. FRONTIERS IN PLANT SCIENCE 2020; 11:736. [PMID: 32582259 PMCID: PMC7289990 DOI: 10.3389/fpls.2020.00736] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 05/07/2020] [Indexed: 05/05/2023]
Abstract
Shoot branching from axillary buds (AXBs) is regulated by a network of inhibitory and promotive forces, which includes hormones. In perennials, the dwarfed stature of the embryonic shoot inside AXBs is indicative of gibberellin (GA) deficiency, suggesting that AXB activation and outgrowth require GA. Nonetheless, the role of GA in branching has remained obscure. We here carried out comprehensive GA transcript and metabolite analyses in hybrid aspen, a perennial branching model. The results indicate that GA has an inhibitory as well as promotive role in branching. The latter is executed in two phases. While the expression level of GA2ox is high in quiescent AXBs, decapitation rapidly downregulated it, implying increased GA signaling. In the second phase, GA3ox2-mediated de novo GA-biosynthesis is initiated between 12 and 24 h, prior to AXB elongation. Metabolite analyzes showed that GA1/4 levels were typically high in proliferating apices and low in the developmentally inactive, quiescent AXBs, whereas the reverse was true for GA3/6. To investigate if AXBs are differently affected by GA3, GA4, and GR24, an analog of the branch-inhibitor hormone strigolactone, they were fed into AXBs of single-node cuttings. GA3 and GA4 had similar effects on GA and SL pathway genes, but crucially GA3 induced AXB abscission whereas GA4 promoted outgrowth. Both GA3 and GA4 strongly upregulated GA2ox genes, which deactivate GA1/4 but not GA3/6. Thus, the observed production of GA3/6 in quiescent AXBs targets GA1/4 for GA2ox-mediated deactivation. AXB quiescence can therefore be maintained by GA3/6, in combination with strigolactone. Our discovery of the distinct tasks of GA3 and GA4 in AXB activation might explain why the role of GA in branching has been difficult to decipher. Together, the results support a novel paradigm in which GA3/6 maintains high levels of GA2ox expression and low levels of GA4 in quiescent AXBs, whereas activation and outgrowth require increased GA1/4 signaling through the rapid reduction of GA deactivation and subsequent GA biosynthesis.
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Affiliation(s)
| | - Päivi L. H. Rinne
- Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
| | - Danuše Tarkowská
- Laboratory of Growth Regulators, Faculty of Sciences, Institute of Experimental Botany of the Czech Academy of Sciences, Palacký University Olomouc, Olomouc, Czechia
| | - Miroslav Strnad
- Laboratory of Growth Regulators, Faculty of Sciences, Institute of Experimental Botany of the Czech Academy of Sciences, Palacký University Olomouc, Olomouc, Czechia
| | - Christiaan van der Schoot
- Department of Plant Sciences, Norwegian University of Life Sciences, Ås, Norway
- *Correspondence: Christiaan van der Schoot,
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