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Li Y, Zhu G, Sun H, Xiang D, Zhang C, Li Z, Liu P. Genome-wide analysis of LOG family genes in castor and RcLOG5 enhances drought, salt, and cold stress tolerance in Arabidopsis thaliana. Gene 2024; 913:148398. [PMID: 38518901 DOI: 10.1016/j.gene.2024.148398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/14/2024] [Accepted: 03/19/2024] [Indexed: 03/24/2024]
Abstract
The gene encoding the specific phosphohydrolase LONELY GUY (LOG) plays an important role in the activation of cytokinin and the stress response in plant cells. However, the role of LOG genes in castor bean (Ricinus communis) has not been reported. In this study, we identified a total of nine members of the LOG gene family in the castor bean genome and investigated the upregulated expression of the RcLOG5 gene using transcriptome data analysis. We found that the RcLOG5 gene exhibited tissue-specific expression and was activated by polyethylene glycol, NaCl, low temperature, and abscisic acid stress. The subcellular localization results showed that the RcLOG5 gene is mainly located in the cytoplasm. Based on phenotypic and physiological indicators, namely root length, peroxidase activity, and malondialdehyde content, overexpression of the RcLOG5 gene not only improved the drought resistance, salt tolerance, and cold tolerance of transgenic Arabidopsis, but also shortened the dormancy period of the transgenic plants. Transcriptomic sequencing revealed that the overexpression of the RcLOG5 gene led to the enrichment of differentially expressed genes in the glutathione metabolism pathway in transgenic Arabidopsis. Moreover, the overexpression plants had higher levels of glutathione and a higher GSH/GSSG ratio under stress compared to the wild type. Therefore, we inferred that the RcLOG5 gene may be responsible for regulating cell membrane homeostasis by reducing the accumulation of reactive oxygen species through the glutathione pathway. Overall, the overexpression of the RcLOG5 gene positively regulated the stress resistance of transgenic Arabidopsis. This study provides valuable gene resources for breeding stress-tolerant castor bean varieties.
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Affiliation(s)
- Yanxiao Li
- College of Agriculture, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Guishuang Zhu
- College of Agriculture, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Haonan Sun
- College of Agriculture, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Dianjun Xiang
- College of Agriculture, Inner Mongolia Minzu University, Tongliao 028000, China.
| | - Chunlan Zhang
- College of Life Science and Food Engineering, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Zhigang Li
- College of Agriculture, Inner Mongolia Minzu University, Tongliao 028000, China
| | - Peng Liu
- College of Agriculture, Inner Mongolia Minzu University, Tongliao 028000, China.
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2
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Rathore RS, Mishra M, Pareek A, Singla-Pareek SL. Concurrent improvement of rice grain yield and abiotic stress tolerance by overexpression of cytokinin activating enzyme LONELY GUY (OsLOG). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 211:108635. [PMID: 38688114 DOI: 10.1016/j.plaphy.2024.108635] [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: 09/30/2023] [Revised: 03/25/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024]
Abstract
Meristem activity is important for normal plant growth as well as adaptive plastic development under abiotic stresses. Cytokinin has been recognized to have a major role in regulating meristem function which is controlled by cytokinin activating enzymes by fine-tuning the concentrations and spatial distribution of its bioactive forms. It was previously reported that LONELY GUY (LOG) acts in the direct activation pathway of cytokinin in rice shoot meristems. LOG has a cytokinin specific phosphoribohydrolase activity, which transforms inactive cytokinin nucleotides into active free bases. Here, we explored the role of OsLOG in controlling meristem activity mediated by cytokinin and its effects on growth, development, and stress resilience of rice plants. Overexpression of OsLOG in rice led to significant alterations in cytokinin levels in the inflorescence meristem, leading to enhanced plant growth, biomass and grain yield under both non-stress as well as stress conditions such as drought and salinity. Moreover, our study provides insight into how overexpression of OsLOG improves the ability of plants to withstand stress. The OsLOG-overexpressing lines exhibit reduced accumulation of H2O2 along with elevated antioxidant enzyme activities, thereby maintaining better redox homeostasis under stress conditions. This ultimately reduces the negative impact of stresses on grain yield and improves harvest index, as evidenced by observations in the OsLOG-overexpressing lines. In summary, our study emphasizes the diverse role of OsLOG, not only in regulating plant growth and yield via cytokinin but also in enhancing adaptability to abiotic stresses. This highlights its potential to improve crop yield and promote sustainable agriculture.
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Affiliation(s)
- Ray Singh Rathore
- Plant Stress Biology, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Manjari Mishra
- Plant Stress Biology, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India
| | - Ashwani Pareek
- Stress Physiology and Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Sneh Lata Singla-Pareek
- Plant Stress Biology, International Centre for Genetic Engineering and Biotechnology, New Delhi, 110067, India.
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3
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Zhao J, Wang J, Liu J, Zhang P, Kudoyarova G, Liu CJ, Zhang K. Spatially distributed cytokinins: Metabolism, signaling, and transport. PLANT COMMUNICATIONS 2024:100936. [PMID: 38689499 DOI: 10.1016/j.xplc.2024.100936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 04/25/2024] [Accepted: 04/28/2024] [Indexed: 05/02/2024]
Abstract
Cytokinins are mobile phytohormones that regulate plant growth, development, and environmental adaptability. The major cytokinin species include isopentenyl adenine (iP), trans-zeatin (tZ), cis-zeatin (cZ), and dihydrozeatin (DZ). The spatial distributions of different cytokinin species in different organelles, cells, tissues, and organs are primarily shaped by biosynthesis via isopentenyltransferases (IPT), cytochrome P450 monooxygenase, and 5'-ribonucleotide phosphohydrolase and by conjugation or catabolism via glycosyltransferase or cytokinin oxidase/dehydrogenase. Cytokinins bind to histidine receptor kinases in the endoplasmic reticulum or plasma membrane and relay signals to response regulators in the nucleus via shuttle proteins known as histidine phosphotransfer proteins. The movements of cytokinins from sites of biosynthesis to sites of signal perception usually require long-distance, intercellular, and intracellular transport. In the past decade, ATP-binding cassette (ABC) transporters, purine permeases (PUP), AZA-GUANINE RESISTANT (AZG) transporters, equilibrative nucleoside transporters (ENT), and Sugars Will Eventually Be Exported transporters (SWEET) have been characterized as involved in cytokinin transport processes. This review begins by introducing the spatial distributions of various cytokinins and the subcellular localizations of the proteins involved in their metabolism and signaling. Highlights focus on an inventory of the characterized transporters involved in cytokinin compartmentalization, including long-distance, intercellular, and intracellular transport, and the regulation of the spatial distributions of cytokinins by environmental cues. Future directions for cytokinin research are also discussed.
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Affiliation(s)
- Jiangzhe Zhao
- Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants, College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, P.R. China
| | - Jingqi Wang
- Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants, College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, P.R. China
| | - Jie Liu
- Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants, College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, P.R. China
| | - Penghong Zhang
- Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants, College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, P.R. China
| | - Guzel Kudoyarova
- Ufa Institute of Biology, Ufa Federal Research Center, RAS, Prospekt Oktyabrya 69, Ufa 450054, Russia
| | - Chang-Jun Liu
- Biology Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Kewei Zhang
- Zhejiang Provincial Key Laboratory of Biotechnology on Specialty Economic Plants, College of Life Sciences, Zhejiang Normal University, Jinhua, Zhejiang 321004, P.R. China.
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4
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Jameson PE. Zeatin: The 60th anniversary of its identification. PLANT PHYSIOLOGY 2023; 192:34-55. [PMID: 36789623 PMCID: PMC10152681 DOI: 10.1093/plphys/kiad094] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/06/2023] [Accepted: 02/08/2023] [Indexed: 05/03/2023]
Abstract
While various labs had shown cell division-inducing activity in a variety of plant extracts for over a decade, the identification of zeatin (Z) in 1964, the first known naturally occurring cytokinin, belongs to Letham and co-workers. Using extracts from maize (Zea mays), they were the first to obtain crystals of pure Z and in sufficient quantity for structural determination by MS, NMR, chromatography, and mixed melting-point analysis. This group also crystallized Z-9-riboside (ZR) from coconut (Cocos nucifera) milk. However, their chemical contributions go well beyond the identification of Z and ZR and include two unambiguous syntheses of trans-Z (to establish stereochemistry), the synthesis of 3H-cytokinins that facilitated metabolic studies, and the synthesis of deuterated internal standards for accurate mass spectral quantification. Letham and associates also unequivocally identified Z nucleotide, the 7-and 9-glucoside conjugates of Z, and the O-glucosides of Z, ZR, dihydro Z (DHZ) and DHZR as endogenous compounds and as metabolites of exogenous Z. Their contributions to the role of cytokinins in plant physiology and development were also substantial, especially the role of cytokinins moving in the xylem. These biological advances are described and briefly related to the genetic/molecular biological contributions of others that established that plants have an absolute requirement for cytokinin.
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Affiliation(s)
- Paula Elizabeth Jameson
- School of Biological Sciences, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand
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5
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Iqbal S, Wang X, Mubeen I, Kamran M, Kanwal I, Díaz GA, Abbas A, Parveen A, Atiq MN, Alshaya H, Zin El-Abedin TK, Fahad S. Phytohormones Trigger Drought Tolerance in Crop Plants: Outlook and Future Perspectives. FRONTIERS IN PLANT SCIENCE 2022; 12:799318. [PMID: 35095971 PMCID: PMC8792739 DOI: 10.3389/fpls.2021.799318] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/27/2021] [Indexed: 05/20/2023]
Abstract
In the past and present, human activities have been involved in triggering global warming, causing drought stresses that affect animals and plants. Plants are more defenseless against drought stress; and therefore, plant development and productive output are decreased. To decrease the effect of drought stress on plants, it is crucial to establish a plant feedback mechanism of resistance to drought. The drought reflex mechanisms include the physical stature physiology and biochemical, cellular, and molecular-based processes. Briefly, improving the root system, leaf structure, osmotic-balance, comparative water contents and stomatal adjustment are considered as most prominent features against drought resistance in crop plants. In addition, the signal transduction pathway and reactive clearance of oxygen are crucial mechanisms for coping with drought stress via calcium and phytohormones such as abscisic acid, salicylic acid, jasmonic acid, auxin, gibberellin, ethylene, brassinosteroids and peptide molecules. Furthermore, microorganisms, such as fungal and bacterial organisms, play a vital role in increasing resistance against drought stress in plants. The number of characteristic loci, transgenic methods and the application of exogenous substances [nitric oxide, (C28H48O6) 24-epibrassinolide, proline, and glycine betaine] are also equally important for enhancing the drought resistance of plants. In a nutshell, the current review will mainly focus on the role of phytohormones and related mechanisms involved in drought tolerance in various crop plants.
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Affiliation(s)
- Shehzad Iqbal
- Faculty of Agriculture Sciences, Universidad De Talca, Talca, Chile
| | - Xiukang Wang
- Shaanxi Key Laboratory of Chinese Jujube, College of Life Sciences, Yan’an University, Yan’an, China
| | - Iqra Mubeen
- Key Lab of Integrated Crop Disease and Pest Management of Shandong Province, College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, China
| | - Muhammad Kamran
- School of Agriculture, Food, and Wine, The University of Adelaide, Adelaide, SA, Australia
| | - Iqra Kanwal
- Department of Plant Pathology, University of Agriculture, Faisalabad, Pakistan
| | - Gonzalo A. Díaz
- Faculty of Agriculture Sciences, Universidad De Talca, Talca, Chile
| | - Aqleem Abbas
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Aasma Parveen
- Department of Soil Science, Faculty of Agriculture and Environmental Sciences, The Islamia University of Bahawalpur, Bahawalpur, Pakistan
| | - Muhammad Nauman Atiq
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Huda Alshaya
- Cell and Molecular Biology, University of Arkansas, Fayetteville, NC, United States
| | - Tarek K. Zin El-Abedin
- Department of Agriculture and Biosystems Engineering, Faculty of Agriculture (El-Shatby), Alexandria University, Alexandria, Egypt
| | - Shah Fahad
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresource, College of Tropical Crops, Hainan University, Haikou, China
- Department of Agronomy, The University of Haripur, Haripur, Pakistan
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Wang R, Liu L, Kong Z, Li S, Lu L, Chen G, Zhang J, Qanmber G, Liu Z. Identification of GhLOG gene family revealed that GhLOG3 is involved in regulating salinity tolerance in cotton (Gossypium hirsutum L.). PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2021; 166:328-340. [PMID: 34147725 DOI: 10.1016/j.plaphy.2021.06.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 06/08/2021] [Indexed: 06/12/2023]
Abstract
Cytokinin (CK) is an important plant hormone that promotes plant cell division and differentiation, and participates in salt response under osmotic stress. LOGs (LONELY GUY) are CK-activating enzymes involved in CK synthesis. The LOG gene family has not been comprehensively characterized in cotton. In this study we identified 151 LOG genes from nine plant species, including 28 LOG genes in Gossypium hirsutum. Phylogenetic analysis divided LOG genes into three groups. Exon/intron structures and protein motifs of GhLOG genes were highly conserved. Synteny analysis revealed that several gene loci were highly conserved between the A and D sub-genomes of G. hirsutum with purifying selection pressure during evolution. Expression profiles showed that most LOG genes were constitutively expressed in eight different tissues. Furthermore, LOG genes can be regulated by abiotic stresses and phytohormone treatments. Moreover, subcellular localization revealed that GhLOG3_At resides inside the cell membrane. Overexpression of GhLOG3 enhanced salt tolerance in Arabidopsis. Virus-induced gene silencing (VIGS) of GhLOG3_At in cotton enhanced sensitivity of plants to salt stress with increased H2O2 contents and decreased chlorophyll and proline (PRO) activity. Our results suggested that GhLOG3_At induces salt stress tolerance in cotton, and provides a basis for the use of CK synthesis genes to regulate cotton growth and stress resistance.
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Affiliation(s)
- Rong Wang
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China.
| | - Le Liu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China.
| | - Zhaosheng Kong
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China; State Key Laboratory of Plant Genomics, Institute of Microbiology, Academy of Seed Design, Chinese Academy of Sciences, Beijing, China.
| | - Shengdong Li
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China.
| | - Lili Lu
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, Henan, China.
| | - Guoquan Chen
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China.
| | - Jiaxin Zhang
- Saint John Paul the Great Catholic High School, Dumfries, VA, 22172, USA.
| | - Ghulam Qanmber
- State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang, 455000, Henan, China.
| | - Zhao Liu
- Zhengzhou Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China.
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Basunia MA, Nonhebel HM. Hormonal regulation of cereal endosperm development with a focus on rice (Oryza sativa). FUNCTIONAL PLANT BIOLOGY : FPB 2019; 46:493-506. [PMID: 30955506 DOI: 10.1071/fp18323] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/13/2019] [Indexed: 05/07/2023]
Abstract
The endosperm of cereal grain forms the staple diet for most of the world's population, and feeds much of their stock. Grain size and quality are determined largely by events taking place during coenocytic nuclear division, endosperm cellularisation and cell differentiation, and the production of storage molecules. Thus, understanding the complex signalling processes occurring at each of these steps is essential for maintaining and improving our food supply. Here, we critically review evidence for the effects of phytohormones on grain size, as well as hormone homeostasis, signalling and crosstalk. We focus on rice endosperm due to the importance of rice as a food crop and a model grass, as well as its relative neglect in recent reviews; however, data from other cereals are also discussed due to strong evidence for conserved signalling networks operating during grain development. Discussion is restricted to auxin, cytokinin, ethylene, abscisic acid and gibberellin. Our review highlights the need for accurate hormone determinations combined with information on gene expression. We present evidence for separate, localised signalling roles for auxin at different stages of grain development and highlight key research questions for other hormones where much less data are available.
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Affiliation(s)
- Mafroz A Basunia
- School of Science and Technology, University of New England, Armidale, NSW 2350, Australia
| | - Heather M Nonhebel
- School of Science and Technology, University of New England, Armidale, NSW 2350, Australia; and Corresponding author.
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8
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Kang J, Lee Y, Sakakibara H, Martinoia E. Cytokinin Transporters: GO and STOP in Signaling. TRENDS IN PLANT SCIENCE 2017; 22:455-461. [PMID: 28372884 DOI: 10.1016/j.tplants.2017.03.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/23/2017] [Accepted: 03/02/2017] [Indexed: 05/04/2023]
Abstract
Cytokinins are phytohormones essential for cytokinesis and many other physiological and developmental processes in planta. Long-distance transport and intercellular transport have been postulated. For these processes, the existence of cytokinin transporters has been suggested. Recently, a transporter loading the xylem (AtABCG14) and another for cellular import (AtPUP14) have been discovered. AtABCG14 participates in the xylem loading process of cytokinins and contributes to the positive regulation of shoot growth. The cellular importer AtPUP14 is required to suppress cytokinin signaling. A role of a transporter as stop signal is a new paradigm for a hormone transporter.
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Affiliation(s)
- Joohyun Kang
- Institute of Plant and Microbial Biology, University Zurich, Zollikerstrasse 107, 8008 Zürich, Switzerland.
| | - Youngsook Lee
- Department of Life Sciences, Pohang University of Science and Technology (POSTECH), Pohang 37673, Korea
| | - Hitoshi Sakakibara
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; RIKEN Center for Sustainable Resource Science, 1-7-22 Suehiro, Tsurumi, Yokohama 230-0045, Japan
| | - Enrico Martinoia
- Institute of Plant and Microbial Biology, University Zurich, Zollikerstrasse 107, 8008 Zürich, Switzerland
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Abstract
The history of auxin and cytokinin biology including the initial discoveries by father-son duo Charles Darwin and Francis Darwin (1880), and Gottlieb Haberlandt (1919) is a beautiful demonstration of unceasing continuity of research. Novel findings are integrated into existing hypotheses and models and deepen our understanding of biological principles. At the same time new questions are triggered and hand to hand with this new methodologies are developed to address these new challenges.
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Affiliation(s)
- Andrej Hurný
- Institute of Science and Technology, Am Campus 1, 3400, Klosterneuburg, Austria
| | - Eva Benková
- Institute of Science and Technology, Am Campus 1, 3400, Klosterneuburg, Austria.
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10
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Zürcher E, Müller B. Cytokinin Synthesis, Signaling, and Function--Advances and New Insights. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 324:1-38. [PMID: 27017005 DOI: 10.1016/bs.ircmb.2016.01.001] [Citation(s) in RCA: 82] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The plant hormones referred to as cytokinins are chemical signals that control numerous developmental processes throughout the plant life cycle, including gametogenesis, root meristem specification, vascular development, shoot and root growth, meristem homeostasis, senescence, and more. In addition, they mediate responses to environmental cues such as light, stress, and nutrient conditions. The core mechanistics of cytokinin metabolism and signaling have been elucidated, but more layers of regulation, additional functions, and interactions with other signals are continuously discovered and described. In this chapter, we recapitulate the highlights of over 100 years of cytokinin research covering its isolation, the elucidation of phosphorelay signaling, and how cytokinin functions in various developmental contexts including its interaction with other pathways. Additionally, given cytokinin's paracrine signaling mechanism, we postulate that cellular exporters for cytokinins exist.
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Affiliation(s)
- E Zürcher
- Department of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich Zurich, Switzerland
| | - B Müller
- Department of Plant and Microbial Biology, Zurich-Basel Plant Science Center, University of Zurich Zurich, Switzerland.
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Shivashankar S, Sumathi M. Do seed VLCFAs trigger spongy tissue formation in Alphonso mango by inducing germination? J Biosci 2015; 40:375-87. [PMID: 25963264 DOI: 10.1007/s12038-015-9515-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Spongy tissue is a physiological disorder in Alphonso mango caused by the inception of germination-associated events during fruit maturation on the tree, rendering the fruit inedible. Inter-fruit competition during active fruit growth is a major contributing factor for the disorder which leads to reduced fat content in spongy tissue affected fruits. This study was, therefore, carried out to determine the possible association between seed fats and ST formation. The study of the fat content during fruit growth showed that it increased gradually from 40 percent fruit maturity. At 70 percent maturity, however, there was a sudden increase of fat content of whole fruit, leading to acute competition and resulting in differential allocation of resources among developing fruits. As a result, the seed in spongy-tissue-affected mature ripe fruit showed a marked drop in the levels of fats and the two very long chain fatty acids (VLCFAs), tetracosanoic acid and hexacosanoic acid together with an increase of linolenic acid and a fall in oleic acid contents, which are known to be key determinants for the initiation of pre-germination events in seed. Subsequently, a rise in the level of cytokinin and gibberellins in ST seed associated with a fall in abscisic acid level clearly signalled the onset of germination. Concurrently, a significant reduction in the ratio of linolenic acid/linoleic acid in pulp led to the loss of membrane integrity, cell death and the eventual formation of spongy tissue. Based on the above, it is concluded that a significant reduction in the biosynthesis of VLCFAs in seeds during fruit growth might trigger pre-germination events followed by a cascade of biochemical changes in the pulp, leading to lipid peroxidation and membrane injury in pulp culminating in ST development. Thus, this study presents crucial experimental evidence to highlight the critical role played by VLCFAs in inducing ST formation in Alphonso mango during the pre-harvest phase of fruit growth.
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Affiliation(s)
- Seshadri Shivashankar
- Division of Plant Physiology and Biochemistry, Indian Institute of Horticultural Research, Bangalore, India,
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12
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Asgher M, Khan MIR, Anjum NA, Khan NA. Minimising toxicity of cadmium in plants--role of plant growth regulators. PROTOPLASMA 2015; 252:399-413. [PMID: 25303855 DOI: 10.1007/s00709-014-0710-4] [Citation(s) in RCA: 140] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 09/23/2014] [Indexed: 05/20/2023]
Abstract
A range of man-made activities promote the enrichment of world-wide agricultural soils with a myriad of chemical pollutants including cadmium (Cd). Owing to its significant toxic consequences in plants, Cd has been one of extensively studied metals. However, sustainable strategies for minimising Cd impacts in plants have been little explored. Plant growth regulators (PGRs) are known for their role in the regulation of numerous developmental processes. Among major PGRs, plant hormones (such as auxins, gibberellins, cytokinins, abscisic acid, jasmonic acid, ethylene and salicylic acid), nitric oxide (a gaseous signalling molecule), brassinosteroids (steroidal phytohormones) and polyamines (group of phytohormone-like aliphatic amine natural compounds with aliphatic nitrogen structure) have gained attention by agronomist and physiologist as a sustainable media to induce tolerance in abiotic-stressed plants. Considering recent literature, this paper: (a) overviews Cd status in soil and its toxicity in plants, (b) introduces major PGRs and overviews their signalling in Cd-exposed plants, (c) appraises mechanisms potentially involved in PGR-mediated enhanced plant tolerance to Cd and (d) highlights key aspects so far unexplored in the subject area.
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Affiliation(s)
- Mohd Asgher
- Department of Botany, Aligarh Muslim University, Aligarh, 202002, India
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Del Bianco M, Giustini L, Sabatini S. Spatiotemporal changes in the role of cytokinin during root development. THE NEW PHYTOLOGIST 2013; 199:324-338. [PMID: 23692218 DOI: 10.1111/nph.12338] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 04/12/2013] [Indexed: 05/07/2023]
Abstract
The root is a dynamic system whose structure is regulated by a complex network of interactions between hormones. The primary root meristem is specified in the embryo. After germination, the primary root meristem grows and then reaches a final size that will be maintained during the life of the plant. Subsequently, secondary structures such as lateral roots and root nodules form via the re-specification of differentiated cells. Cytokinin plays key roles in the regulation of root development. Down-regulation of the cytokinin response is required for the specification of a new stem cell niche, during both embryo and lateral root development. In the root meristem, cytokinin signalling regulates the longitudinal zonation of the meristem by controlling cell differentiation. Moreover, cytokinin regulates radial patterning of root vasculature by promoting protophloem cell identity and by spatially inhibiting protoxylem formation. In this review, an effort is made to describe the known details of the role of cytokinin during root development, taking into account also the interactions between cytokinin and other hormones. Attention is given on the dynamicity of cytokinin signalling output during different developmental events. Indeed, there is much evidence that the effects of cytokinin change as organs grow, underlining the importance of the spatiotemporal specificity of cytokinin signalling.
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Affiliation(s)
- Marta Del Bianco
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
| | - Leonardo Giustini
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
| | - Sabrina Sabatini
- Laboratory of Functional Genomics and Proteomics of Model Systems, Dipartimento di Biologia e Biotecnologie, Università di Roma, Sapienza - via dei Sardi, 70-00185, Rome, Italy
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El-Showk S, Ruonala R, Helariutta Y. Crossing paths: cytokinin signalling and crosstalk. Development 2013; 140:1373-83. [PMID: 23482484 DOI: 10.1242/dev.086371] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cytokinins are a major class of plant hormones that are involved in various aspects of plant development, ranging from organ formation and apical dominance to leaf senescence. Cytokinin and auxin have long been known to interact antagonistically, and more recent studies have shown that cytokinins also interact with other plant hormones to regulate plant development. A growing body of research has begun to elucidate the molecular and genetic underpinnings of this extensive crosstalk. The rich interconnections between the synthesis, perception and transport networks of these plant hormones provide a wide range of opportunities for them to modulate, amplify or buffer one another. Here, we review this exciting and rapidly growing area of cytokinin research.
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Affiliation(s)
- Sedeer El-Showk
- Institute of Biotechnology/Department of Biosciences, University of Helsinki, Helsinki FI-00014, Finland
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15
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Liu X, Bereźniak T, Panek JJ, Jezierska-Mazzarello A. Theoretical study of zeatin – A plant hormone and potential drug for neural diseases – On the basis of DFT, MP2 and target docking. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2012.12.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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16
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Abstract
Despite long-standing observations on diverse cytokinin actions, the discovery path to cytokinin signaling mechanisms was tortuous. Unyielding to conventional genetic screens, experimental innovations were paramount in unraveling the core cytokinin signaling circuitry, which employs a large repertoire of genes with overlapping and specific functions. The canonical two-component transcription circuitry involves His kinases that perceive cytokinin and initiate signaling, as well as His-to-Asp phosphorelay proteins that transfer phosphoryl groups to response regulators, transcriptional activators, or repressors. Recent advances have revealed the complex physiological functions of cytokinins, including interactions with auxin and other signal transduction pathways. This review begins by outlining the historical path to cytokinin discovery and then elucidates the diverse cytokinin functions and key signaling components. Highlights focus on the integration of cytokinin signaling components into regulatory networks in specific contexts, ranging from molecular, cellular, and developmental regulations in the embryo, root apical meristem, shoot apical meristem, stem and root vasculature, and nodule organogenesis to organismal responses underlying immunity, stress tolerance, and senescence.
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Affiliation(s)
- Ildoo Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, Korea.
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Leonard NJ, Hecht SM, Skoog F, Schmitz RY. Cytokinins: synthesis, mass spectra, and biological activity of compounds related to zeatin. Proc Natl Acad Sci U S A 2010; 63:175-82. [PMID: 16591745 PMCID: PMC534019 DOI: 10.1073/pnas.63.1.175] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Compounds related to dihydrozeatin that define the influence of the location of the hydroxyl group along the side chain have been synthesized and tested for cytokinin activity. The compounds compared are in the series: 6-(X-hydroxy-3-methylbutylamino)purines and their ribosides, where X = 2, 3, and 4.Hydroxy substitution on the 4-position of the side chain enhances, but in the 2-, 3-, or 2- and 3- positions, decreases cytokinin activity as compared with the unsubstituted isopentyl (or isopentenyl) chains. This differential influence of the position of the hydroxyl group in the N(6)-chain holds also for the similarly related 9-beta-D-ribofuranosides. The relatively higher activity of 3,4-dihydroxy as compared with 2,3-dihydroxy derivatives is consistent with this position effect.Compounds related to zeatin possessing side-chain ester moieties have also been synthesized and tested comparatively. Among these, 6-(4-acetoxy-3-methyl-trans-2-butenylamino)purine is at least as active as zeatin, the most active presently known cytokinin in the tobacco bioassay, whereas the analog, methyl 2-methyl-4-(purin-6-ylamino)-trans-crotonate, with the ester function effectively reversed, has vastly lower activity, and its riboside is practically inactive.
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Affiliation(s)
- N J Leonard
- DEPARTMENT OF CHEMISTRY AND CHEMICAL ENGINEERING, UNIVERSITY OF ILLINOIS, URBANA
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19
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Amasino R. 1955: kinetin arrives: the 50th anniversary of a new plant hormone. PLANT PHYSIOLOGY 2005; 138:1177-84. [PMID: 16009993 PMCID: PMC1176392 DOI: 10.1104/pp.104.900160] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2005] [Revised: 04/28/2005] [Accepted: 04/28/2005] [Indexed: 05/03/2023]
Affiliation(s)
- Richard Amasino
- Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
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20
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Affiliation(s)
- Atsuhiro Oka
- Laboratory of Molecular Biology, Institute for Chemical Research, Kyoto University, Uji, Japan.
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21
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Emery, Leport, Barton, Turner, Atkins. cis-isomers of cytokinins predominate in chickpea seeds throughout their development. PLANT PHYSIOLOGY 1998; 117:1515-23. [PMID: 9701607 PMCID: PMC34915 DOI: 10.1104/pp.117.4.1515] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/1998] [Accepted: 05/18/1998] [Indexed: 05/20/2023]
Abstract
Trans-isomers of cytokinins (CK) are thought to predominate and have greater biological activity than corresponding cis-isomers in higher plants. However, this study demonstrates a system within which the predominant CK are cis-isomers. CK were measured at four developmental stages in developing chickpea (Cicer arietinum L. cultivar Kaniva) seeds by gas chromatography-mass spectrometry. Concentrations were highest at an early endospermic fluid stage and fell considerably when the cotyledons expanded. The cis-isomers of zeatin nucleotide ([9R-MP]Z), zeatin riboside ([9R]Z), and zeatin (Z) were present in greater concentrations than those of corresponding trans-isomers: (trans)[9R-MP]Z, (trans)[9R]Z, (trans)Z, or dihydrozeatin riboside. Dihydrozeatin, dihydrozeatin nucleotide, and the isopentenyl-type CK concentrations were either low or not detectable. Root xylem exudates also contained predominantly cis-isomers of [9R-MP]Z and [9R]Z. Identities of (cis)[9R]Z and (cis)Z were confirmed by comparison of ion ratios and retention indices, and a full spectrum was obtained for (cis)[9R]Z. Tissues were extracted under conditions that minimized the possibility of RNase hydrolysis of tRNA following tissue disruption, being a significant source of the cis-CK. Since no isomerization of (trans)[2H]CK internal standards occurred, it is unlikely that the cis-CK resulted from enzymic or nonenzymic isomerization during extraction. Although quantities of total CK varied, similar CK profiles were found among three different chickpea cultivars and between adequately watered and water-stressed plants. Developing chickpea seeds will be a useful system for investigating the activity of cis-CK or determining the origin and metabolism of free CK.
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Affiliation(s)
- Emery
- Centre for Legumes in Mediterranean Agriculture (R.J.N.E., L.L., C.A. A., J.E.B., N.C.T.)
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22
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Hormonal Regulation of Seed Development. ADVANCES IN CELLULAR AND MOLECULAR BIOLOGY OF PLANTS 1997. [DOI: 10.1007/978-94-015-8909-3_4] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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23
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Карадимова М, Карадимова М, Karadimova M. IN VITRO МЕТОДИ ЗА ИНДУЦИРАНЕ НА КАЛУС И РЕГЕНЕРАЦИЯ НА РАСТЕНИЯ ПРИ ПШЕНИЦАТА. BIOTECHNOL BIOTEC EQ 1993. [DOI: 10.1080/13102818.1993.10819406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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24
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Boerjan W, Genetello C, Van Montagu M, Inzé D. A new bioassay for auxins and cytokinins. PLANT PHYSIOLOGY 1992; 99:1090-8. [PMID: 16668975 PMCID: PMC1080588 DOI: 10.1104/pp.99.3.1090] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The authors have developed a sensitive bioassay that can be used to detect auxins as well as cytokinins. The bioassay is based on the expression in transformed tobacco (Nicotiana tabacum) mesophyll protoplasts of a chimeric gene, consisting of the upstream sequences of the Agrobacterium tumefaciens gene 5, coupled to the coding sequence of the beta-glucuronidase. The expression of this gene is induced by the presence of both auxin and cytokinin in the culture medium. Using this assay, indole-3-acetic acid was detected at 5 x 10(-8) molar, whereas trans-zeatin could be detected at 5 x 10(-11) molar. The assay can be performed in microtiter plates, allowing numerous samples to be analyzed simultaneously. Only 2.5 x 10(5) protoplasts are required for one individual assay in 250 microliters of culture medium and for qualitative results, the reaction is readily visualized by ultraviolet light.
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Affiliation(s)
- W Boerjan
- Laboratorium voor Genetica, Universiteit Gent, B-9000 Gent, Belgium
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25
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Shadid B, van der Plas HC. A convenient new synthesis of the allylic pyrophosphate of trans-zeatin. Tetrahedron 1990. [DOI: 10.1016/s0040-4020(01)81370-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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26
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Chapter 3 Purine Alkaloids. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/s0099-9598(08)60240-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
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27
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Soriano-Garc�a M, Toscano RA, Arroyo-Reyna JA. Stereochemistry and hydrogen bonding of cytokinins: Crystal and molecular structure of 6-(4-hydroxy-3-methyl-cis-2-butenyl) aminopurine (cis-zeatin). ACTA ACUST UNITED AC 1987. [DOI: 10.1007/bf01160913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Fosket DE, Tepfer DA. Hormonal regulation of growth in cultured plant cells. IN VITRO 1978; 14:63-75. [PMID: 624559 DOI: 10.1007/bf02618175] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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31
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Mizuno K, Komamine A. Isolation and identification of substances inducing formation of tracheary elements in cultured carrot-root slices. PLANTA 1978; 138:59-62. [PMID: 24413942 DOI: 10.1007/bf00392915] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/1976] [Accepted: 10/11/1977] [Indexed: 06/03/2023]
Abstract
The roots of a carrot (Daucus carota L.) cultivar, Kuroda-gosun, contain active substances causing formation of tracheary elements in cultured root phloem slices. In the roots of another carrot cultivar, Hokkaidô-gosun, such substances could not be detected but when root-phloem slices of this cultivar were cultured in the light, active substances were produced in the tissue. From the behavior in thinlayer chromatography and data from gas chromatography and mass spectrometry, the major active substance isolated from the roots of Kuroda-gosun was identified as zeatin ribonucleoside. Hydrolysis with HCl and alkaline phosphatase of the active substance in the amphoteric fraction from root slices of Hokkaidô-gosun, cultured in the light, gave rise to zeatin and zeatin ribonucleoside, respectively, indicating that the active substance produced in this material in the light may be zeatin ribonucleotide.
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Affiliation(s)
- K Mizuno
- Department of Botany, Faculty of Science, University of Tokyo, Hongo, 113, Tokyo, Japan
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32
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Short KC, Tepfer DA, Fosket DE. Regulation of polyribosome formation and cell division in cultured soybean cells by cytokinin. J Cell Sci 1974; 15:75-87. [PMID: 4407320 DOI: 10.1242/jcs.15.1.75] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABSTRACT
Cytokinin was shown to be required for cell division in cultured cells of Glycine max var. Sodifury. This cytokinin-induced mitotic activity was correlated with a high cellular content of polysomes. Within 24 h after transfer to a cytokinin-containing medium there was a 4”5-fold increase in the percentage of ribosomes bound as polyribosomes, as determined by sucrose density gradient centrifugation of extracted ribosomal material. Relatively high levels of polysomes and mitotic activity were maintained through the first 6 days of the culture period on cytokinin-containing medium. Thereafter, both cell division activity and the percentage of polyribosomes declined progressively with increasing time in culture. A comparatively small increase in polyribosomes occurred within 24 h of transfer to medium lacking cytokinins, followed by the progressive decline of the level of polyribosomes. The time course of cytokinin-induced polyribosome formation was determined by treating cells with cytokinin after they had been cultured for 24 h on a medium lacking cytokinin. Under these conditions there was a rapid increase in polyribosomes over the next 3 h with no detectable lag period, and near maximal levels of polyribosomes after 6 h of treatment. The initial stimulation of polyribosome formation by cytokinin was not blocked by actinomycin D. Cytokinin was shown to have a comparatively small effect on the ribonuclease activity in extracts of these cells.
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33
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Rodrigues Pereira A, Houwen P, Deurenberg-Vos H, Pey E. Cytokinins and the bacterial symbiosis of Ardisia species. ACTA ACUST UNITED AC 1972. [DOI: 10.1016/s0044-328x(72)80166-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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34
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Krasnuk M, Witham FH, Tegley JR. Cytokinins extracted from pinto bean fruit. PLANT PHYSIOLOGY 1971; 48:320-4. [PMID: 16657790 PMCID: PMC396858 DOI: 10.1104/pp.48.3.320] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Extracts from various parts of Phaseolus vulgaris L. var. Pinto plants were found to exhibit cytokinin activity with the highest levels present in extracts of the fruit tissue. To separate the cytokinins present in the fruit, extracts were chromatographed in several solvent systems. Bioassays of chromatograms indicated the presence of active factors in those regions of migration associated with several known N-6-substituted aminopurines.Ultraviolet and mass spectral studies confirm the presence of a mixture of N-6-substituted aminopurines in the active material isolated by cation exchange resin chromatography. The evidence strongly supports the conclusions that dihydrozeatin is naturally occurring as the free base and possibly as a ribonucleoside. Further, zeatin appears to occur mainly as a glycosidic compound which is altered by KMnO(4) treatment and is hydrolyzed under acid conditions.
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Affiliation(s)
- M Krasnuk
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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35
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Tegley JR, Witham FH, Krasnuk M. Chromatographic analysis of a cytokinin from tissue cultures of crown-gall. PLANT PHYSIOLOGY 1971; 47:581-5. [PMID: 16657664 PMCID: PMC396730 DOI: 10.1104/pp.47.4.581] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Extracts from tissue cultures of crown-gall from Parthenocissus tricuspidata (Sieb. and Zucc.) Planch. exhibited cell division activity in the soybean cytokinin assay. The chromatographic migration of one component, responsible for most of the activity, is similar to that of zeatin ribonucleoside. In addition, acid hydrolysis of the active region taken from chromatograms and of an eluate from a cation-exchange resin column resulted in the production of an active free-base-like derivative. Since the derivative and the parent compound lose activity after KMnO(4) treatment, they are believed to possess an unsaturated constituent essential for biological activity. The major active factor present in crown-gall from Parthenocissus tricuspidata is therefore distinct from the nicotinamide derivative reported to be present in Vinca rosea L. tumor cells.
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Affiliation(s)
- J R Tegley
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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36
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37
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Tal M, Imber D, Itai C. Abnormal Stomatal Behavior and Hormonal Imbalance in flacca, a Wilty Mutant of Tomato: I. Root Effect and Kinetin-like Activity. PLANT PHYSIOLOGY 1970; 46:367-72. [PMID: 16657469 PMCID: PMC396598 DOI: 10.1104/pp.46.3.367] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The wilty tomato mutant, flacca, and the normal variety, Rheinlands Ruhm, were compared for kinetin-like activity in ontogeny. The mutant wilts easily because its stomata resist closure. This stomatal resistance decreases with age. The occurrence of a root factor which induces stomatal opening was inferred from grafting experiments. It was hypothesized that the excessive stomatal openings in the mutant may result from excess of kinetin-like activity in the leaf of that plant. In addition, it was suggested that the closure of stomata in the aging mutant is due to a decrease of kinetin-like activity with age. Kinetin-like activity in the leaf was determined by incorporation of labeled leucine. The concentration of cytokinins in root exudate and leaf extract was determined by the soybean callus assay. Evidence was presented of higher kinetin-like activity in the leaves of the mutant and higher cytokinin concentration in its root exudate. Cytokinin concentration in the shoot was found to be only slightly higher in the mutant than in the normal plants. Kinetin-like activity in the leaf and cytokinin concentration of root exudate decreased with age in both mutant and normal plants. Kinetin-like activity in the leaves of mutant plants, which phenocopy the normal variety as a result of continuous application of abscisic acid, was lower than in control mutant plants. The significance of these findings per se and in connection with stomatal behavior is discussed.
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Affiliation(s)
- M Tal
- Negev Institute for Arid Zone Research, Beer-Sheva, Israel
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38
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Abstract
Extracts of seeds of pumpkin (Cucurbita pepo Linn.) contain three chromatographically distinguishable cytokinins which are held on Dowex 50-W and are extractable by ethanol and n-butanol. Two of the active factors are precipitable by silver nitrate at acidic pH. The chromatographic behavior and the spectral characteristics of one of these cytokinins are similar to those of zeatin. However, the R(F) values of the other two active compounds do not match with those of any of the known natural cytokinins.
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Affiliation(s)
- G R Gupta
- Department of Botany, University of Delhi, Delhi 7, India
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39
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Miura GA, Miller CO. Cytokinins from a variant strain of cultured soybean cells. PLANT PHYSIOLOGY 1969; 44:1035-9. [PMID: 16657153 PMCID: PMC396210 DOI: 10.1104/pp.44.7.1035] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A strain of soybean cells capable of growing on a tissue culture medium lacking a cytokinin produced at least 3 compounds active in the soybean cytokinin assay. The characteristics of these compounds were consistent with their being zeatin in the free form, zeatin ribonucleoside and zeatin ribonucleotide. Although the conversion from a cytokinin dependent to independent condition in this strain parallels the change of normal cells to crown gall tumor state in terms of the capacity to synthesize cell division substances, the soybean factors are distinct from the nicotinamide derivatives reported for tumor cells of Vinca.
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Affiliation(s)
- G A Miura
- Department of Botany, Indiana University, Bloomington, Indiana 47401
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40
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Fosket DE, Torrey JG. Hormonal control of cell proliferation and xylem differentiation in cultured tissues of Glycine max var. Biloxi. PLANT PHYSIOLOGY 1969; 44:871-80. [PMID: 5816361 PMCID: PMC396179 DOI: 10.1104/pp.44.6.871] [Citation(s) in RCA: 43] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The relationship between tracheary element differentiation, cell proliferation and growth hormones was examined in agar-grown soybean callus. The time course of cell division and tracheary element formation in tissues grown on a medium containing 5 x 10(-7)m kinetin and 10(-5)m NAA was determined by means of maceration technique. After a slight lag period, a logarithmic increase in cell number was observed through the twelfth day of the culture period. Cell numbers increased at a considerably slower rate after the twelfth day. The rate of tracheary element formation varied with the rate of cell proliferation. Tracheary elements increased logarithmically during the log phase of growth. As the rate of cell division decreased after the twelfth day of culture, the rate of tracheary element formation also decreased. In the presence of 10(-5)m NAA, cell number increased as the kinetin concentration was increased between 10(-9) and 10(-6)m. However, tracheary element formation was not initiated unless the kinetin concentration was 5 x 10(-8)m or above. When the Biloxi callus was subcultured repeatedly on media containing 10(-8)m kinetin, a tracheary element-free population of cells was obtained. This undifferentiated tissue produced tracheary elements upon transfer to a medium containing 5 x 10(-7)m kinetin. In the presence of 5 x 10(-7)m kinetin, NAA stimulated cell proliferation between 10(-7) and 10(-5)m, but no tracheary elements were formed without auxin, or with 10(-7)m NAA. Neither NAA nor kinetin at any concentration tested stimulated tracheary element formation in the absence of an effective level of the other hormone. However, 2,4-D at 10(-7) or 10(-6)m promoted both cell proliferation and tracheary element differentiation in the absence of an exogenous cytokinin.
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41
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Esashi Y, Leopold AC. Cotyledon expansion as a bioassay for cytokinins. PLANT PHYSIOLOGY 1969; 44:618-20. [PMID: 16657110 PMCID: PMC396135 DOI: 10.1104/pp.44.4.618] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- Y Esashi
- Department of Horticulture, Purdue University, Lafayette, Indiana 47907
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42
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Eastwood D, Tavener RJ, Laidman DL. Sequential action of cytokinin and gibberellic acid in wheat aleurone tissue. Nature 1969; 221:1267. [PMID: 5773850 DOI: 10.1038/2211267a0] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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43
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Rubery PH, Fosket DE. Changes in phenylalanine ammonia-lyase activity during xylem differentiation in Coleus and soybean. PLANTA 1969; 87:54-62. [PMID: 24504715 DOI: 10.1007/bf00386964] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/1969] [Indexed: 05/08/2023]
Abstract
Xylem differentiation was induced in cultured Coleus internode slices when grown in the light on a simple agar/sucrose/IAA medium and in darkgrown soybean callus tissue when cultured on a complex defined medium containing 5×10(-7) M kinetin. In the Coleus system, the activity of phenylalanine ammonialyase followed the same time course as the formation of lignified wound vessel members. The specific activity of PAL was higher in the soybean callus tissues grown on 5×10(-7) M kinetin, which produced tracheary elements, than in the soybean tissue grown on 10(-8) M kinetin, which did not produce tracheids. These observations suggest that PAL is a "marker enzyme" for xylogenesis and that PAL activity may be a rate limiting step in lignification.
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Affiliation(s)
- P H Rubery
- Department of Biochemistry, University of Cambridge, England
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44
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Helgeson JP. The cytokinins. Synthetic and naturally occurring N6-substituted adenine derivatives profoundly affect plant growth. Science 1968; 161:974-81. [PMID: 4876488 DOI: 10.1126/science.161.3845.974] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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45
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Witham FH. Effect of 2,4-dichlorophenoxyacetic Acid on the cytokinin requirement of soybean cotyledon and tobacco stem pith callus tissues. PLANT PHYSIOLOGY 1968; 43:1455-7. [PMID: 16656937 PMCID: PMC1087039 DOI: 10.1104/pp.43.9.1455] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Affiliation(s)
- F H Witham
- Department of Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
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46
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47
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48
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KHALIFAH RA, LEWIS LN. Cytokinins in Citrus: Isolation of a Cell Division Factor from Lemon Seeds. Nature 1966. [DOI: 10.1038/2121472b0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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49
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Helgeson JP, Leonard NJ. Cytokinins: identification of compounds isolated from Corynebacterium fascians. Proc Natl Acad Sci U S A 1966; 56:60-3. [PMID: 4226131 PMCID: PMC285674 DOI: 10.1073/pnas.56.1.60] [Citation(s) in RCA: 85] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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50
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Klämbt D, Thies G, Skoog F. Isolation of cytokinins from Corynebacterium fascians. Proc Natl Acad Sci U S A 1966; 56:52-9. [PMID: 4226130 PMCID: PMC285673 DOI: 10.1073/pnas.56.1.52] [Citation(s) in RCA: 101] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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