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Xu X, Hu Q, Wang J, Wang X, Lou L, Xu J, Yang X, Chen X. A 2-bp deletion in the protein kinase domain region of the ERECTA-like receptor kinase gene in cucumber results in short internode phenotype. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2023; 327:111536. [PMID: 36402238 DOI: 10.1016/j.plantsci.2022.111536] [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: 05/25/2022] [Revised: 10/31/2022] [Accepted: 11/10/2022] [Indexed: 06/16/2023]
Abstract
Cucumber varieties with shortend internodes require less space than regular vining varieties, thus have great significance for germplasm improvement. Here, we found a novel spontaneous cucumber mutant si107 that exhibited short intenodes (si), smaller leaves, fruits, and seeds. The decrease in longitudinal cell length led to the shortened internodes of si107. The genetic analysis revealed a single recessive gene si-2 that was responsible for the mutation. Through multiple lines of evidence, we demonstrated that CsSI is the possible candidate gene for si-2, which encodes an ERECTA leucine-rich repeat receptor-like kinase. The shortened internode in si107 is attributed to a 2-bp deletion in the protein kinase domain region of this gene. The expression of CsSI was higher in the internodes, petioles, and fruit peels of si107 than in the wild type (WT). The transcriptome analysis between the si107 mutant and WT indicated that differentially expressed genes were significantly enriched in the plant hormone signal transduction pathway, in which auxin signal genes comprised the largest group, and all were downregulated in si107. Phytohormone quantitation confirmed that endogenous auxin levels in the stems of si107 were decreased. Our results provide new insights into the molecular mechanisms underlying the internode length control in cucumber.
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Affiliation(s)
- Xuewen Xu
- School of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou, Jiangsu 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Qiming Hu
- School of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Jiaxi Wang
- School of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Xueting Wang
- School of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Lina Lou
- Jiangsu Key Laboratory for Horticultural Crop Genetic Improvement, Institute of Vegetable Crops, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210014, China
| | - Jun Xu
- School of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Xiaodong Yang
- School of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou, Jiangsu 225009, China
| | - Xuehao Chen
- School of Horticulture and Landscape Architecture, Yangzhou University, Yangzhou, Jiangsu 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu 225009, China.
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Involvement of Auxin and Brassinosteroid in Dwarfism of Autotetraploid Apple (Malus × domestica). Sci Rep 2016; 6:26719. [PMID: 27216878 PMCID: PMC4877651 DOI: 10.1038/srep26719] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 05/09/2016] [Indexed: 11/23/2022] Open
Abstract
The plant height is an important trait in fruit tree. However, the molecular mechanism on dwarfism is still poorly understood. We found that colchicine-induced autotetraploid apple plants (Malus × domestica) exhibited a dwarf phenotype. The vertical length of cortical parenchyma cells was shorter in autotetraploids than in diploids, by observing paraffin sections. Hormone levels of indoleacetic acid (IAA) and brassinosteroid (BR) were significantly decreased in 3- and 5-year-old autotetraploid plants. Digital gene expression (DGE) analysis showed that the differentially expressed genes were mainly involved in IAA and BR pathways. microRNA390 was significantly upregulated according to microarray analysis. Exogenous application of IAA and BR promoted stem elongation of both apple plants grown in medium. The results show that dwarfing in autotetraploid apple plants is most likely regulated by IAA and BR. The dwarf phenotype of autotetraploid apple plants could be due to accumulation of miR390 after genome doubling, leading to upregulation of apple trans-acting short-interfering RNA 3 (MdTAS3) expression, which in turn downregulates the expression of MdARF3. Overall, this leads to partial interruption of the IAA and BR signal transduction pathway. Our study provides important insights into the molecular mechanisms underlying dwarfism in autopolyploid apple plants.
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Mariani ME, Madoery RR, Fidelio GD. Auxins action on Glycine max secretory phospholipase A2 is mediated by the interfacial properties imposed by the phytohormones. Chem Phys Lipids 2015; 189:1-6. [PMID: 25987194 DOI: 10.1016/j.chemphyslip.2015.05.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 04/24/2015] [Accepted: 05/09/2015] [Indexed: 11/28/2022]
Abstract
Secretory phospholipase A2 (sPLA2) are soluble enzymes that catalyze the conversion of phospholipids to lysophospholipids and free fatty acids at membrane interfaces. The effect of IAA and IPA auxins over the activity of recombinant sPLA2 isoforms from Glycine max was studied using membrane model systems including mixed micelles and Langmuir lipid monolayers. Both phytohormones stimulate the activity of both plant sPLA2 using DLPC/Triton mixed micelles as substrate. To elucidate the mechanism of action of the phytohormones, we showed that both auxins are able to self-penetrate lipid monolayers and cause an increment in surface pressure and an expansion of lipid/phytohormone mixed interfaces. The stimulating effect of auxins over phospholipase A2 activity was still present when using Langmuir mixed monolayers as organized substrate regardless of sPLA2 source (plant or animal). All the data suggest that the stimulating effect of auxins over sPLA2 is due to a more favorable interfacial environment rather to a direct effect over the enzyme.
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Affiliation(s)
- María Elisa Mariani
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, UNC, CONICET, Departamento de Química Biológica, Fac. de Cs. Químicas, Universidad Nacional de Córdoba. Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
| | - Ricardo Román Madoery
- Departamento de Fundamentación Biológica, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Gerardo Daniel Fidelio
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, UNC, CONICET, Departamento de Química Biológica, Fac. de Cs. Químicas, Universidad Nacional de Córdoba. Haya de la Torre y Medina Allende, Ciudad Universitaria, X5000HUA, Córdoba, Argentina.
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Ross JJ, Weston DE, Davidson SE, Reid JB. Plant hormone interactions: how complex are they? PHYSIOLOGIA PLANTARUM 2011; 141:299-309. [PMID: 21214880 DOI: 10.1111/j.1399-3054.2011.01444.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Models describing plant hormone interactions are often complex and web-like. Here we assess several suggested interactions within one experimental system, elongating pea internodes. Results from this system indicate that at least some suggested interactions between auxin, gibberellins (GAs), brassinosteroids (BRs), abscisic acid (ABA) and ethylene do not occur in this system or occur in the reverse direction to that suggested. Furthermore, some of the interactions are relatively weak and may be of little physiological relevance. This is especially true if plant hormones are assumed to show a log-linear response curve as many empirical results suggest. Although there is strong evidence to support some interactions between hormones (e.g. auxin stimulating ethylene and bioactive GA levels), at least some of the web-like complexities do not appear to be justified or are overstated. Simpler and more targeted models may be developed by dissecting out key interactions with major physiological effects.
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Affiliation(s)
- John J Ross
- School of Plant Science, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia
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Sorce C, Picciarelli P, Calistri G, Lercari B, Ceccarelli N. The involvement of indole-3-acetic acid in the control of stem elongation in dark- and light-grown pea (Pisum sativum) seedlings. JOURNAL OF PLANT PHYSIOLOGY 2007; 165:482-9. [PMID: 17706834 DOI: 10.1016/j.jplph.2007.03.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 02/15/2007] [Accepted: 03/12/2007] [Indexed: 05/16/2023]
Abstract
We investigated the role of auxin on stem elongation in pea (Pisum sativum L.) grown for 10d in continuous darkness or under low-irradiance blue, red, far red and white light. The third internode of treated seedlings was peeled and the tissues (epidermis and cortex+central cylinder) were separately analyzed for the concentration of free and conjugated indole-3-acetic acid (IAA). Under red, far red and white light internode elongation was linearly related with the free IAA content of all internode tissues, suggesting that phytochrome-dependent inhibition of stem growth may be mediated by a decrease of free IAA levels in pea seedlings. The correlation between IAA and internode elongation, however, did not hold for blue light-grown seedlings. The hypothesis that the growth response under low-irradiance blue light might be correlated with the lack of phytochrome B signalling and changes in gibberellin metabolism is discussed in view of current knowledge on hormonal control of stem growth.
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Affiliation(s)
- Carlo Sorce
- Department of Biology, University of Pisa, via L. Ghini, 5, 56126 Pisa, Italy.
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6
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Chawla R, DeMason DA. Molecular expression of PsPIN1, a putative auxin efflux carrier gene from pea (Pisum sativum L.). PLANT GROWTH REGULATION 2004. [PMID: 0 DOI: 10.1007/s10725-004-2139-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
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Wolbang CM, Chandler PM, Smith JJ, Ross JJ. Auxin from the developing inflorescence is required for the biosynthesis of active gibberellins in barley stems. PLANT PHYSIOLOGY 2004; 134:769-76. [PMID: 14730077 PMCID: PMC344552 DOI: 10.1104/pp.103.030460] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2003] [Revised: 08/18/2003] [Accepted: 10/29/2003] [Indexed: 05/19/2023]
Abstract
Multiple gibberellins (GAs) were quantified in the stems of intact, decapitated, and decapitated auxin-treated barley (Hordeum vulgare) plants. Removal of the developing inflorescence reduced the endogenous levels of indole-3-acetic acid (IAA), GA(1), and GA(3) and increased the level of GA(29) in internodal and nodal tissues below the site of excision. Application of IAA to the excised stump restored GA levels to normal in almost all cases. The conversion of [(14)C]GA(20) to bioactive [(14)C]GA(1) and of [(14)C]GA(5) to bioactive [(14)C]GA(3) was reduced by decapitation, and IAA application was able to restore conversion rates back to the levels found in intact plants. The amount of mRNA for the principal vegetative 3-oxidase (converting GA(20) to GA(1), and GA(5) to GA(3)) was decreased in decapitated plants and restored by IAA application. The results indicate that the inflorescence of barley is a source of IAA that is transported basipetally into the internodes and nodes where bioactive GA(1) and GA(3) are biosynthesized. Thus, IAA is required for normal GA biosynthesis in stems, acting at multiple steps in the latter part of the pathway.
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Affiliation(s)
- Carla M Wolbang
- School of Plant Science, University of Tasmania, GPO Box 252-55, Hobart, Tasmania 7001, Australia
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8
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Swarup R, Parry G, Graham N, Allen T, Bennett M. Auxin cross-talk: integration of signalling pathways to control plant development. PLANT MOLECULAR BIOLOGY 2002; 49:411-26. [PMID: 12036264 DOI: 10.1007/978-94-010-0377-3_12] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Plants sense and respond to endogenous signals and environmental cues to ensure optimal growth and development. Plant cells must integrate the myriad transduction events into a comprehensive network of signalling pathways and responses. The phytohormone auxin occupies a central place within this transduction network, frequently acting in conjunction with other signals, to co-ordinately regulate cellular processes such as division, elongation and differentiation. As a non-cell autonomous signal, auxin also interacts with other signalling pathways to regulate inter-cellular developmental processes. As part of this especially themed edition of Plant Molecular Biology, we will review examples of 'cross-talk' between auxin and other signalling pathways. Given the current state of knowledge, we have deliberately focused our efforts reviewing auxin interactions with other phytohormone and light signalling pathways. We conclude by discussing how new genomic approaches and the Arabidopsis genome sequence are likely to impact this area of research in the future.
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Affiliation(s)
- Ranjan Swarup
- School of Biosciences, Sutton Bonington, University of Nottingham, Leicestershire, UK
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Ross JJ, O'Neill DP, Smith JJ, Kerckhoffs LH, Elliott RC. Evidence that auxin promotes gibberellin A1 biosynthesis in pea. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2000; 21:547-52. [PMID: 10758505 DOI: 10.1046/j.1365-313x.2000.00702.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
In shoots of the garden pea, the bioactive gibberellin (GA1) is synthesised from GA20, and the enzyme which catalyses this step (a GA 3-oxidase -- PsGA3ox1) is encoded by Mendel's LE gene. It has been reported previously that decapitation of the shoot (excision of the apical bud) dramatically reduces the conversion of [3H]GA20 to [3H]GA1 in stems, and here we show that endogenous GA1 and PsGA3ox1 transcript levels are similarly reduced. We show also that these effects of decapitation are completely reversed by application of the auxin indole-3-acetic acid (IAA) to the 'stump' of decapitated plants. Gibberellin A20 is also converted to an inactive product, GA29, and this step is catalysed by a GA 2-oxidase, PsGA2ox1. In contrast to PsGA3ox1, PsGA2ox1 transcript levels were increased by decapitation and reduced by IAA application. Decapitation and IAA treatment did not markedly affect the level of GA1 precursors. It is suggested that in intact pea plants, auxin from the apical bud moves into the elongating internodes where it (directly or indirectly) maintains PsGA3ox1 transcript levels and, consequently, GA1 biosynthesis.
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Affiliation(s)
- J J Ross
- School of Plant Science, University of Tasmania, GPO Box 252-55, Hobart, Tasmania 7001, Australia.
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11
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Haga K, Iino M. Auxin-growth relationships in maize coleoptiles and pea internodes and control by auxin of the tissue sensitivity to auxin. PLANT PHYSIOLOGY 1998; 117:1473-1486. [PMID: 9701602 PMCID: PMC34910 DOI: 10.1104/pp.117.4.1473] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/1998] [Accepted: 05/18/1998] [Indexed: 05/22/2023]
Abstract
Growth of a zone of maize (Zea mays L.) coleoptiles and pea (Pisum sativum L.) internodes was greatly suppressed when the organ was decapitated or ringed at an upper position with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA) mixed with lanolin. The transport of apically applied 3H-labeled indole-3-acetic acid (IAA) was similarly inhibited by NPA. The growth suppressed by NPA or decapitation was restored by the IAA mixed with lanolin and applied directly to the zone, and the maximal capacity to respond to IAA did not change after NPA treatment, although it declined slightly after decapitation. The growth rate at IAA saturation was greater than the rate in intact, nontreated plants. It was concluded that growth is limited and controlled by auxin supplied from the apical region. In maize coleoptiles the sensitivity to IAA increased more than 3 times when the auxin level was reduced over a few hours with NPA treatment. This result, together with our previous result that the maximal capacity to respond to IAA declines in pea internodes when the IAA level is enhanced for a few hours, indicates that the IAA concentration-response relationship is subject to relatively slow adaptive regulation by IAA itself. The spontaneous growth recovery observed in decapitated maize coleoptiles was prevented by an NPA ring placed at an upper position of the stump, supporting the view that recovery is due to regenerated auxin-producing activity. The sensitivity increase also appeared to participate in an early recovery phase, causing a growth rate greater than in intact plants.
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Affiliation(s)
- K Haga
- Botanical Gardens, Faculty of Science, Osaka City University, Kisaichi, Katano-shi, Osaka 576, Japan
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12
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Gray WM, Ostin A, Sandberg G, Romano CP, Estelle M. High temperature promotes auxin-mediated hypocotyl elongation in Arabidopsis. Proc Natl Acad Sci U S A 1998; 95:7197-202. [PMID: 9618562 PMCID: PMC22781 DOI: 10.1073/pnas.95.12.7197] [Citation(s) in RCA: 443] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Physiological studies with excised stem segments have implicated the plant hormone indole-3-acetic acid (IAA or auxin) in the regulation of cell elongation. Supporting evidence from intact plants has been somewhat more difficult to obtain, however. Here, we report the identification and characterization of an auxin-mediated cell elongation growth response in Arabidopsis thaliana. When grown in the light at high temperature (29 degreesC), Arabidopsis seedlings exhibit dramatic hypocotyl elongation compared with seedlings grown at 20 degreesC. This temperature-dependent growth response is sharply reduced by mutations in the auxin response or transport pathways and in seedlings containing reduced levels of free IAA. In contrast, mutants deficient in gibberellin and abscisic acid biosynthesis or in ethylene response are unaffected. Furthermore, we detect a corresponding increase in the level of free IAA in seedlings grown at high temperature, suggesting that temperature regulates auxin synthesis or catabolism to mediate this growth response. Consistent with this possibility, high temperature also stimulates other auxin-mediated processes including auxin-inducible gene expression. Based on these results, we propose that growth at high temperature promotes an increase in auxin levels resulting in increased hypocotyl elongation. These results strongly support the contention that endogenous auxin promotes cell elongation in intact plants.
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Affiliation(s)
- W M Gray
- Department of Biology, Indiana University Bloomington, IN 47405, USA
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Rodrigo MJ, López-Díaz I, García-Martínez JL. The characterization of gio, a new pea mutant, shows the role of indoleacetic acid in the control of fruit development by the apical shoot. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 1998; 14:83-90. [PMID: 15494055 DOI: 10.1046/j.1365-313x.1998.00100.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Fruit-set and fruit growth in pea (Pisum sativum L.) depend on gibberellins (GAs). The authors have isolated a new pea mutant, gio, which appeared spontaneously within the population of the cultivar Alaska, characterized by unpollinated ovaries much less sensitive to applied GAs. The mutant also has elongated peduncles, and is taller than the wild-type (WT) because the upper plant internodes are longer. Contrary to WT, the gio ovaries respond very little to benzylaminopurine (BAP) and 2,4-dichlorophenoxyacetic acid, but become fully sensitive to GA(3) when this hormone is applied together with BAP. The gio phenotype is determined by a mutation at a single mendelian locus. The mutation is recesive, shows incomplete penetrance, and its expression depends on environmental culture conditions. The sensitivity of the ovaries to GA(3) can be recovered by removing the apical shoot (plant decapitation) and by blocking the transport of indoleacetic acid (IAA) from the apical shoot with 2,3,5-triiodobenzoic acid. The content of IAA in methanolic extracts and phloematic exudates of the apical shoot of gio is about double that in the WT. The rate of transport of [(3)H]IAA applied to the apex of the mutant is also twice that in the WT. This indicates that the insensitivity of the gio ovaries to GAs is due to the inhibitory effect of the higher basipetal IAA transport from the shoot. The interaction between the fruit and the apical shoot mediated by IAA probably also involves cytokinins transported from the basal part of the plant.
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Affiliation(s)
- M J Rodrigo
- Instituto de Biología, Molecular y Celular de Plantas, Universidad Politécnica de Valencia-CSIC, Camino de Vera s/n, 46022-Valencia, Spain
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Hutchinson MJ, KrishnaRaj S, Saxena PK. Inhibitory effect of GA 3 on the development of thidiazuron-induced somatic embryogenesis in geranium (Pelargonium xhortorum Bailey) hypocotyl cultures. PLANT CELL REPORTS 1997; 16:435-438. [PMID: 30727657 DOI: 10.1007/bf01146789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/1996] [Revised: 07/31/1996] [Accepted: 08/20/1996] [Indexed: 06/09/2023]
Abstract
Somatic embryogenesis in geranium (Pelargonium xhortorum Bailey cv 'Scarlet Orbit Improved') can be achieved by incubating hypocotyl explants on MS medium supplemented with thidiazuron (TDZ; 10 μM for 3 days followed by subculture on medium devoid of any plant growth regulators. The presence of gibberellins (GAs) during both the induction and expression phases of embryogenesis was significantly detrimental to somatic embryo formation on the hypocotyl explants. The addition of the GA-synthesis inhibitors paclobutrazol, uniconazole or ancymidol during the period of growth and differentiation of somatic embryos increased the number of somatic embryos formed on each explant. However, paclobutrazol added during the period of induction had no significant influence on somatic embryo formation. Results suggest that both exogenously supplied as well as endogenous GAs play a role, albeit a negative one, on somatic embryogenesis of geranium.
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Affiliation(s)
- M J Hutchinson
- Department of Horticultural Science, University of Guelph, N1G 2W1, Guelph, Ontario, Canada
| | - S KrishnaRaj
- Department of Horticultural Science, University of Guelph, N1G 2W1, Guelph, Ontario, Canada
| | - P K Saxena
- Department of Horticultural Science, University of Guelph, N1G 2W1, Guelph, Ontario, Canada
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Ezura H, Harberd NP. Endogenous gibberellin levels influence in-vitro shoot regeneration in Arabidopsis thaliana (L.) Heynh. PLANTA 1995; 197:301-305. [PMID: 8547816 DOI: 10.1007/bf00202651] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The regeneration of shoot buds from callus cells in vitro is an important technique in modern plant genetic manipulation. Whilst it is clear that genetic factors play a major role in determining the ability of callus cells to become organized into regenerating shoot buds, the precise nature of these factors remains unknown. Here we show that callus derived from mutants of Arabidopsis thaliana which have reduced levels of endogenous bioactive gibberellins (GAs), or reduced responsivity to GAs, regenerates shoot buds more readily than does callus derived from wild-type controls. In addition, exogenous GA reduces, and exogenous paclobutrazol (a GA-bio-synthesis inhibitor) increases, the frequency of shoot bud regeneration from wild-type callus. These results show that GA levels play a role in regulating shoot bud regeneration from callus, and suggest that variation in endogenous GA levels or responsivity may account for a major component of the genetic variation in shoot bud regeneration frequency described in other species.
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Affiliation(s)
- H Ezura
- Department of Molecular Genetics, John Innes Centre, Norwich, UK
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Behringer FJ, Davies PJ, Reid JB. PHYTOCHROME REGULATION OF STEM GROWTH AND INDOLE-3-ACETIC ACID LEVELS IN THE lv AND Lv GENOTYPES OF Pisum. Photochem Photobiol 1992. [DOI: 10.1111/j.1751-1097.1992.tb02221.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Behringer FJ, Davies PJ. Indole-3-acetic acid levels after phytochrome-mediated changes in the stem elongation rate of dark- and light-grown Pisum seedlings. PLANTA 1992. [PMID: 24178203 DOI: 10.1007/bf01160716] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The effect of red (R) and far-red (FR) light on stem elongation and indole-3-acetic acid (IAA) levels was examined in dwarf and tall Pisum sativum L. seedlings. Red light reduced the extension-growth rate of etiolated seedlings by 70-90% after 3 h, and this inhibition was reversible by FR. Inhibition occurred throughout the growing zone. After 3 h of R, the level of extractable IAA in whole stem sections from the growing zone of etiolated plants either increased or showed no change. By contrast, extractable IAA from epidermal peels consistently decreased 3 h after R treatments. Decreases of 40% were observed for epidermal peels from the top 1 cm of tall plants receiving 3 h R. Brief R treatments resulted in smaller decreases in epidermal IAA levels and these decreases were not as great when FR followed R. In lightgrown plants, end-of-day FR stimulated growth during the following dark period in a photoreversible manner. The uppermost 1 cm of expanding third internodes was most responsive to the FR. Extractable IAA from epidermal peels from the upper 1 cm of third internodes increased by 30% or more 5 h after FR. When R followed the FR the increases were smaller. Levels of IAA in whole stem sections did not change and were twofold greater than in dark-grown plants. In both dark- and light-grown tall plants, IAA levels were lower in epidermal peels than in whole stem segments. These results provide evidence that IAA is compartmentalized at the tissue level within the growing stem and that phytochrome regulation of stem elongation rates may be partly based on modulating the level of IAA within the epidermis.
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Affiliation(s)
- F J Behringer
- Section of Plant Biology, Cornell University, 14853, Ithaca, NY, USA
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The role of indole-3-acetic acid in mediating changes in stem elongation of etiolated pisum seedlings following exposure to light. ACTA ACUST UNITED AC 1992. [DOI: 10.1007/978-94-011-2458-4_51] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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