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Krahmer J, Fankhauser C. Environmental Control of Hypocotyl Elongation. ANNUAL REVIEW OF PLANT BIOLOGY 2024; 75:489-519. [PMID: 38012051 DOI: 10.1146/annurev-arplant-062923-023852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The hypocotyl is the embryonic stem connecting the primary root to the cotyledons. Hypocotyl length varies tremendously depending on the conditions. This developmental plasticity and the simplicity of the organ explain its success as a model for growth regulation. Light and temperature are prominent growth-controlling cues, using shared signaling elements. Mechanisms controlling hypocotyl elongation in etiolated seedlings reaching the light differ from those in photoautotrophic seedlings. However, many common growth regulators intervene in both situations. Multiple photoreceptors including phytochromes, which also respond to temperature, control the activity of several transcription factors, thereby eliciting rapid transcriptional reprogramming. Hypocotyl growth often depends on sensing in green tissues and interorgan communication comprising auxin. Hypocotyl auxin, in conjunction with other hormones, determines epidermal cell elongation. Plants facing cues with opposite effects on growth control hypocotyl elongation through intricate mechanisms. We discuss the status of the field and end by highlighting open questions.
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Affiliation(s)
- Johanna Krahmer
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland;
- Current affiliation: Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark;
| | - Christian Fankhauser
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland;
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Lei L, Zhang JY, Pu D, Liu BZ, Meng XM, Shang QM, Duan YD, Zhang F, Zhang MX, Dong CJ. ABA-responsive AREB1/ABI3-1/ABI5 cascade regulates IAA oxidase gene SlDAO2 to inhibit hypocotyl elongation in tomato. PLANT, CELL & ENVIRONMENT 2023; 46:498-517. [PMID: 36369997 DOI: 10.1111/pce.14491] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 06/16/2023]
Abstract
Hypocotyl elongation is dramatically influenced by environmental factors and phytohormones. Indole-3-acetic acid (IAA) plays a prominent role in hypocotyl elongation, whereas abscisic acid (ABA) is regarded as an inhibitor through repressing IAA synthesis and signalling. However, the regulatory role of ABA in local IAA deactivation remains largely uncharacterized. In this study, we confirmed the antagonistic interplay of ABA and IAA during the hypocotyl elongation of tomato (Solanum lycopersicum) seedlings. We identified an IAA oxidase enzyme DIOXYGENASE FOR AUXIN OXIDATION2 (SlDAO2), and its expression was induced by both external and internal ABA signals in tomato hypocotyls. Moreover, the overexpression of SlDAO2 led to a reduced sensitivity to IAA, and the knockout of SlDAO2 alleviated the inhibitory effect of ABA on hypocotyl elongation. Furthermore, an ABA-responsive regulatory SlAREB1/SlABI3-1/SlABI5 cascade was identified to act upstream of SlDAO2 and to precisely control its expression. SlAREB1 directly bound to the ABRE present in the SlDAO2 promoter to activate SlDAO2 expression, and SlABI3-1 enhanced while SlABI5 inhibited the activation ability of SlAREB1 by directly interacting with SlAREB1. Our findings revealed that ABA might induce local IAA oxidation and deactivation via SlDAO2 to modulate IAA homoeostasis and thereby repress hypocotyl elongation in tomato.
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Affiliation(s)
- Lei Lei
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
- Crop Breeding and Cultivation Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, China
| | - Jing-Ya Zhang
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Dan Pu
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Bing-Zhu Liu
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Xian-Min Meng
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Qing-Mao Shang
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Yun-Dan Duan
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Feng Zhang
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Meng-Xia Zhang
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
| | - Chun-Juan Dong
- Key Laboratory of Horticultural Crop Biology and Germplasm Innovation, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Ministry of Agriculture, Beijing, People's Republic of China
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Mikołajczak K, Kuczyńska A, Krajewski P, Kempa M, Nuc M. Transcriptome profiling disclosed the effect of single and combined drought and heat stress on reprogramming of genes expression in barley flag leaf. FRONTIERS IN PLANT SCIENCE 2023; 13:1096685. [PMID: 36726667 PMCID: PMC9885109 DOI: 10.3389/fpls.2022.1096685] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 12/14/2022] [Indexed: 06/18/2023]
Abstract
Despite numerous studies aimed at unraveling the genetic background of barley's response to abiotic stress, the modulation of the transcriptome induced by combinatorial drought and increased temperature remains largely unrecognized. Very limited studies were done, especially on the flag leaf, which plays an important role in grain filling in cereals. In the present study, transcriptome profiles, along with chlorophyll fluorescence parameters and yield components, were compared between barley genotypes with different flag leaf sizes under single and combined drought and heat stress. High-throughput mRNA sequencing revealed 2,457 differentially expressed genes, which were functionally interpreted using Gene Ontology term enrichment analysis. The transcriptomic signature under double stress was more similar to effects caused by drought than by elevated temperature; it was also manifested at phenotypic and chlorophyll fluorescence levels. Both common and stress-specific changes in transcript abundance were identified. Genes regulated commonly across stress treatments, determining universal stress responses, were associated, among others, with responses to drought, heat, and oxidative stress. In addition, changes specific to the size of the flag leaf blade were found. Our study allowed us to identify sets of genes assigned to various processes underlying the response to drought and heat, including photosynthesis, the abscisic acid pathway, and lipid transport. Genes encoding LEA proteins, including dehydrins and heat shock proteins, were especially induced by stress treatments. Some association between genetic composition and flag leaf size was confirmed. However, there was no general coincidence between SNP polymorphism of genotypes and differential expression of genes induced by stress factors. This research provided novel insight into the molecular mechanisms of barley flag leaf that determine drought and heat response, as well as their co-occurrence.
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Hwang G, Park J, Kim S, Park J, Seo D, Oh E. Overexpression of BBX18 Promotes Thermomorphogenesis Through the PRR5-PIF4 Pathway. FRONTIERS IN PLANT SCIENCE 2021; 12:782352. [PMID: 34899810 PMCID: PMC8651621 DOI: 10.3389/fpls.2021.782352] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 11/03/2021] [Indexed: 05/19/2023]
Abstract
Thermomorphogenesis is the morphological response of plants to an elevation in the ambient temperature, which is mediated by the bHLH transcription factor PIF4. The evening-expressed clock component, PRR5, directly represses the expression of PIF4 mRNA. Additionally, PRR5 interacts with PIF4 protein and represses its transactivation activity, which in turn suppresses the thermoresponsive growth in the evening. Here, we found that the B-box zinc finger protein, BBX18, interacts with PRR5 through the B-Box2 domain. Deletion of the B-Box2 domain abolished the functions of BBX18, including the stimulation of PIF4 mRNA expression and hypocotyl growth. Overexpression of BBX18, and not of B-Box2-deleted BBX18, restored the expression of thermoresponsive genes in the evening. We further show that BBX18 prevents PRR5 from inhibiting PIF4-mediated high temperature responses. Taken together, our results suggest that BBX18 regulates thermoresponsive growth through the PRR5-PIF4 pathway.
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