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Peng S, Ma T, Ma T, Chen K, Dai Y, Ding J, He P, Yu S. Effects of Salt Tolerance Training on Multidimensional Root Distribution and Root-Shoot Characteristics of Summer Maize under Brackish Water Irrigation. PLANTS (BASEL, SWITZERLAND) 2023; 12:3329. [PMID: 37765493 PMCID: PMC10534383 DOI: 10.3390/plants12183329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023]
Abstract
To investigate the impact of brackish water irrigation on the multidimensional root distribution and root-shoot characteristics of summer maize under different salt-tolerance-training modes, a micro-plot experiment was conducted from June to October in 2022 at the experimental station in Hohai University, China. Freshwater irrigation was used as the control (CK), and different concentrations of brackish water (S0: 0.08 g·L-1, S1: 2.0 g·L-1, S2: 4.0 g·L-1, S3: 6.0 g·L-1) were irrigated at six-leaf stage, ten-leaf stage, and tasseling stage, constituting different salt tolerance training modes, referred to as S0-2-3, S0-3-3, S1-2-3, S1-3-3, S2-2-3, and S2-3-3. The results showed that although their fine root length density (FRLD) increased, the S0-2-3 and S0-3-3 treatments reduced the limit of root extension in the horizontal direction, causing the roots to be mainly distributed near the plants. This resulted in decreased leaf area and biomass accumulation, ultimately leading to significant yield reduction. Additionally, the S2-2-3 and S2-3-3 treatments stimulated the adaptive mechanism of maize roots, resulting in boosted fine root growth to increase the FRLD and develop into deeper soil layers. However, due to the prolonged exposure to a high level of salinity, their roots below 30 cm depth senesced prematurely, leading to an inhibition in shoot growth and also resulting in yield reduction of 10.99% and 11.75%, compared to CK, respectively. Furthermore, the S1-2-3 and S1-3-3 treatments produced more reasonable distributions of FRLD, which did not boost fine root growth but established fewer weak areas (FLRD < 0.66 cm-3) in their root systems. Moreover, the S1-2-3 treatment contributed to increasing leaf development and biomass accumulation, compared to CK, whereas it allowed for minimizing yield reduction. Therefore, our study proposed the S1-2-3 treatment as the recommended training mode for summer maize while utilizing brackish water resources.
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Affiliation(s)
- Suhan Peng
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
- Jiangsu Province Engineering Research Center for Agricultural Soil-Water Efficient Utilization, Carbon Sequestration and Emission Reduction, Nanjing 211100, China
| | - Tao Ma
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
- Jiangsu Province Engineering Research Center for Agricultural Soil-Water Efficient Utilization, Carbon Sequestration and Emission Reduction, Nanjing 211100, China
| | - Teng Ma
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
| | - Kaiwen Chen
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
| | - Yan Dai
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
| | - Jihui Ding
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
| | - Pingru He
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
| | - Shuang’en Yu
- College of Agricultural Science and Engineering, Hohai University, Nanjing 211100, China; (S.P.); (Y.D.); (J.D.); (S.Y.)
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Mondal S, Chakraborty D. Root growth and physiological responses in wheat to topsoil and subsoil compaction with or without artificial vertical macropores. Heliyon 2023; 9:e18834. [PMID: 37576250 PMCID: PMC10415892 DOI: 10.1016/j.heliyon.2023.e18834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 07/25/2023] [Accepted: 07/31/2023] [Indexed: 08/15/2023] Open
Abstract
The process of soil compaction can cause various stresses on roots, ultimately limiting their growth and development within the soil. Understanding this phenomenon in real-world conditions can be challenging since the growth of roots is influenced by the soil environment. To investigate this issue, four experiments were conducted to examine the impact of topsoil (two in pots: with clay loam and sandy loam soils under two soil water regimes) and subsoil (in rhizobox: one with clay loam soil and the other with sandy loam soil, containing artificial vertical macropores) compaction on the relationship between edaphic factors and the physiological response of wheat roots. The topsoil compaction reduced root length, volume, and weight by 30-50% and the root diameter by ∼15% compared to the non-compact soil. The effect was reduced in the soil with higher clay content (clay loam), especially under the limited soil water condition. Plant physiological responses were adversely affected by compaction with a reduction in plant height. The transpiration rate was highly impacted (21-47% reduction) with the build-up of intercellular CO2 content in leaves (13-31%), especially with limited water applications. Root growth was severely restricted (>60%) in the compact subsoil layer, although the surface area and volume of roots increased in the overlying non-compact layer. Naturally occurring or artificial vertical macropores acted as escape channels, facilitating the roots to pass through the compact subsoil and grow abundantly in the loose soil below. However, plants in field conditions encounter a mix of loose and compact soil zones. By studying how roots respond to this soil heterogeneity, we can develop strategies to reduce the negative effects of soil compaction.
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Affiliation(s)
| | - Debashis Chakraborty
- Division of Agricultural Physics, ICAR Indian Agricultural Research Institute, New Delhi, 110 012, India
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Su SH, Levine HG, Masson PH. Brachypodium distachyon Seedlings Display Accession-Specific Morphological and Transcriptomic Responses to the Microgravity Environment of the International Space Station. Life (Basel) 2023; 13:life13030626. [PMID: 36983782 PMCID: PMC10058394 DOI: 10.3390/life13030626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/06/2023] [Accepted: 02/16/2023] [Indexed: 03/06/2023] Open
Abstract
Plants have been recognized as key components of bioregenerative life support systems for space exploration, and many experiments have been carried out to evaluate their adaptability to spaceflight. Unfortunately, few of these experiments have involved monocot plants, which constitute most of the crops used on Earth as sources of food, feed, and fiber. To better understand the ability of monocot plants to adapt to spaceflight, we germinated and grew Brachypodium distachyon seedlings of the Bd21, Bd21-3, and Gaz8 accessions in a customized growth unit on the International Space Station, along with 1-g ground controls. At the end of a 4-day growth period, seedling organ’s growth and morphologies were quantified, and root and shoot transcriptomic profiles were investigated using RNA-seq. The roots of all three accessions grew more slowly and displayed longer root hairs under microgravity conditions relative to ground control. On the other hand, the shoots of Bd21-3 and Gaz-8 grew at similar rates between conditions, whereas those of Bd21 grew more slowly under microgravity. The three Brachypodium accessions displayed dramatically different transcriptomic responses to microgravity relative to ground controls, with the largest numbers of differentially expressed genes (DEGs) found in Gaz8 (4527), followed by Bd21 (1353) and Bd21-3 (570). Only 47 and six DEGs were shared between accessions for shoots and roots, respectively, including DEGs encoding wall-associated proteins and photosynthesis-related DEGs. Furthermore, DEGs associated with the “Oxidative Stress Response” GO group were up-regulated in the shoots and down-regulated in the roots of Bd21 and Gaz8, indicating that Brachypodium roots and shoots deploy distinct biological strategies to adapt to the microgravity environment. A comparative analysis of the Brachypodium oxidative-stress response DEGs with the Arabidopsis ROS wheel suggests a connection between retrograde signaling, light response, and decreased expression of photosynthesis-related genes in microgravity-exposed shoots. In Gaz8, DEGs were also found to preferentially associate with the “Plant Hormonal Signaling” and “MAP Kinase Signaling” KEGG pathways. Overall, these data indicate that Brachypodium distachyon seedlings exposed to the microgravity environment of ISS display accession- and organ-specific responses that involve oxidative stress response, wall remodeling, photosynthesis inhibition, expression regulation, ribosome biogenesis, and post-translational modifications. The general characteristics of these responses are similar to those displayed by microgravity-exposed Arabidopsis thaliana seedlings. However, organ- and accession-specific components of the response dramatically differ both within and between species. These results suggest a need to directly evaluate candidate-crop responses to microgravity to better understand their specific adaptability to this novel environment and develop cultivation strategies allowing them to strive during spaceflight.
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Affiliation(s)
- Shih-Heng Su
- Laboratory of Genetics, University of Wisconsin-Madison, 425 G Henry Mall, Madison, WI 53706, USA
- Correspondence: (S.-H.S.); (P.H.M.)
| | - Howard G. Levine
- NASA John F. Kennedy Space Center, Kennedy Space Center, Merritt Island, FL 32899, USA
| | - Patrick H. Masson
- Laboratory of Genetics, University of Wisconsin-Madison, 425 G Henry Mall, Madison, WI 53706, USA
- Correspondence: (S.-H.S.); (P.H.M.)
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Su SH, Keith MA, Masson PH. Gravity Signaling in Flowering Plant Roots. PLANTS (BASEL, SWITZERLAND) 2020; 9:E1290. [PMID: 33003550 PMCID: PMC7601833 DOI: 10.3390/plants9101290] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/24/2020] [Accepted: 09/27/2020] [Indexed: 12/28/2022]
Abstract
Roots typically grow downward into the soil where they anchor the plant and take up water and nutrients necessary for plant growth and development. While the primary roots usually grow vertically downward, laterals often follow a gravity set point angle that allows them to explore the surrounding environment. These responses can be modified by developmental and environmental cues. This review discusses the molecular mechanisms that govern root gravitropism in flowering plant roots. In this system, the primary site of gravity sensing within the root cap is physically separated from the site of curvature response at the elongation zone. Gravity sensing involves the sedimentation of starch-filled plastids (statoliths) within the columella cells of the root cap (the statocytes), which triggers a relocalization of plasma membrane-associated PIN auxin efflux facilitators to the lower side of the cell. This process is associated with the recruitment of RLD regulators of vesicular trafficking to the lower membrane by LAZY proteins. PIN relocalization leads to the formation of a lateral gradient of auxin across the root cap. Upon transmission to the elongation zone, this auxin gradient triggers a downward curvature. We review the molecular mechanisms that control this process in primary roots and discuss recent insights into the regulation of oblique growth in lateral roots and its impact on root-system architecture, soil exploration and plant adaptation to stressful environments.
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Affiliation(s)
| | | | - Patrick H. Masson
- Laboratory of Genetics, University of Wisconsin-Madison, 425G Henry Mall, Madison, WI 53706, USA; (S.-H.S.); (M.A.K.)
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Miyazawa Y, Takahashi H. Molecular mechanisms mediating root hydrotropism: what we have observed since the rediscovery of hydrotropism. JOURNAL OF PLANT RESEARCH 2020; 133:3-14. [PMID: 31797131 PMCID: PMC7082378 DOI: 10.1007/s10265-019-01153-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 11/19/2019] [Indexed: 06/02/2023]
Abstract
Roots display directional growth toward moisture in response to a water potential gradient. Root hydrotropism is thought to facilitate plant adaptation to continuously changing water availability. Hydrotropism has not been as extensively studied as gravitropism. However, comparisons of hydrotropic and gravitropic responses identified mechanisms that are unique to hydrotropism. Regulatory mechanisms underlying the hydrotropic response appear to differ among different species. We recently performed molecular and genetic analyses of root hydrotropism in Arabidopsis thaliana. In this review, we summarize the current knowledge of specific mechanisms mediating root hydrotropism in several plant species.
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Affiliation(s)
- Yutaka Miyazawa
- Faculty of Science, Yamagata University, 1-4-12 Kojirakawa-machi, Yamagata, 990-8560, Japan.
| | - Hideyuki Takahashi
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, 980-8577, Japan
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Muthert LWF, Izzo LG, van Zanten M, Aronne G. Root Tropisms: Investigations on Earth and in Space to Unravel Plant Growth Direction. FRONTIERS IN PLANT SCIENCE 2019; 10:1807. [PMID: 32153599 PMCID: PMC7047216 DOI: 10.3389/fpls.2019.01807] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 12/24/2019] [Indexed: 05/12/2023]
Abstract
Root tropisms are important responses of plants, allowing them to adapt their growth direction. Research on plant tropisms is indispensable for future space programs that envisage plant-based life support systems for long-term missions and planet colonization. Root tropisms encompass responses toward or away from different environmental stimuli, with an underexplored level of mechanistic divergence. Research into signaling events that coordinate tropistic responses is complicated by the consistent coincidence of various environmental stimuli, often interacting via shared signaling mechanisms. On Earth the major determinant of root growth direction is the gravitational vector, acting through gravitropism and overruling most other tropistic responses to environmental stimuli. Critical advancements in the understanding of root tropisms have been achieved nullifying the gravitropic dominance with experiments performed in the microgravity environment. In this review, we summarize current knowledge on root tropisms to different environmental stimuli. We highlight that the term tropism must be used with care, because it can be easily confused with a change in root growth direction due to asymmetrical damage to the root, as can occur in apparent chemotropism, electrotropism, and magnetotropism. Clearly, the use of Arabidopsis thaliana as a model for tropism research contributed much to our understanding of the underlying regulatory processes and signaling events. However, pronounced differences in tropisms exist among species, and we argue that these should be further investigated to get a more comprehensive view of the signaling pathways and sensors. Finally, we point out that the Cholodny-Went theory of asymmetric auxin distribution remains to be the central and unifying tropistic mechanism after 100 years. Nevertheless, it becomes increasingly clear that the theory is not applicable to all root tropistic responses, and we propose further research to unravel commonalities and differences in the molecular and physiological processes orchestrating root tropisms.
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Affiliation(s)
| | - Luigi Gennaro Izzo
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
- *Correspondence: Luigi Gennaro Izzo,
| | - Martijn van Zanten
- Molecular Plant Physiology, Institute of Environmental Biology, Utrecht University, Utrecht, Netherlands
| | - Giovanna Aronne
- Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy
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8
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Erland LAE, Saxena PK, Murch SJ. Melatonin in plant signalling and behaviour. FUNCTIONAL PLANT BIOLOGY : FPB 2018; 45:58-69. [PMID: 32291021 DOI: 10.1071/fp16384] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/29/2017] [Indexed: 05/23/2023]
Abstract
Melatonin is an indoleamine neurotransmitter that has recently become well established as an important multi-functional signalling molecule in plants. These signals have been found to induce several important physiological responses that may be interpreted as behaviours. The diverse processes in which melatonin has been implicated in plants have expanded far beyond the traditional roles for which it has been implicated in mammals, which include sleep, tropisms and reproduction. These functions, however, appear to also be important melatonin mediated processes in plants, though the mechanisms underlying these functions have yet to be fully elucidated. Mediation or redirection of plant physiological processes induced by melatonin can be summarised as a series of behaviours including, among others: herbivore defence, avoidance of undesirable circumstances or attraction to opportune conditions, problem solving and response to environmental stimulus. As the mechanisms of melatonin action are elucidated, its involvement in plant growth, development and behaviour is likely to expand beyond the aspects discussed in this review and hold promise for applications in diverse fundamental and applied plant sciences including conservation, cryopreservation, morphogenesis, industrial agriculture and natural health products.
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Affiliation(s)
- Lauren A E Erland
- Gosling Research Institute for Plant Preservation, Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Ontario, N1G 2W1, Canada
| | - Praveen K Saxena
- Gosling Research Institute for Plant Preservation, Department of Plant Agriculture, University of Guelph, 50 Stone Road E, Guelph, Ontario, N1G 2W1, Canada
| | - Susan J Murch
- Chemistry, University of British Columbia, Okanagan, Kelowna, British Columbia, V1V 1V7, Canada
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Colombi T, Braun S, Keller T, Walter A. Artificial macropores attract crop roots and enhance plant productivity on compacted soils. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 574:1283-1293. [PMID: 27712865 DOI: 10.1016/j.scitotenv.2016.07.194] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/19/2016] [Accepted: 07/27/2016] [Indexed: 05/03/2023]
Abstract
The structure of compacted soils is characterised by decreased (macro-)porosity, which leads to increased mechanical impedance and decreased fluid transport rates, resulting in reduced root growth and crop productivity. Particularly in soils with high mechanical impedance, macropores can be used by roots as pathways of least resistance. This study investigated how different soil physical states relate to whole plant growth and whether roots grow towards spots with favourable soil physical conditions. Experiments were conducted under controlled and field conditions. Soybean (Glycine max L.), wheat (Triticum aestivum L.) and maize (Zea mays L.) were grown on uncompacted soil, compacted soil and compacted soil with artificial macropores. The interactions between roots and artificial macropores were quantified using X-ray computed tomography. Active growth of roots towards artificial macropores was observed for all three species. Roots grew either into macropores (predominantly in maize) or crossed them (predominantly in wheat). The presence of artificial macropores in compacted soil enabled all three species to compensate for decreased early vigour at later developmental stages. These results show that roots sense their physical environment, enabling them to grow towards spots with favourable soil conditions. The different kinds of root-macropore interaction indicated that macropores serve as a path of least resistance and a source of oxygen, both resulting in increased crop productivity on compacted soils.
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Affiliation(s)
- Tino Colombi
- Institute of Agricultural Sciences (IAS), ETH Zurich, Switzerland.
| | - Serge Braun
- Institute of Agricultural Sciences (IAS), ETH Zurich, Switzerland
| | - Thomas Keller
- Agroscope, Department of Natural Resources and Agriculture, Zurich, Switzerland; Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden
| | - Achim Walter
- Institute of Agricultural Sciences (IAS), ETH Zurich, Switzerland
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Nakashima J, Liao F, Sparks JA, Tang Y, Blancaflor EB. The actin cytoskeleton is a suppressor of the endogenous skewing behaviour of Arabidopsis primary roots in microgravity. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16 Suppl 1:142-50. [PMID: 23952736 DOI: 10.1111/plb.12062] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 05/24/2013] [Indexed: 05/11/2023]
Abstract
Before plants can be effectively utilised as a component of enclosed life-support systems for space exploration, it is important to understand the molecular mechanisms by which they develop in microgravity. Using the Biological Research in Canisters (BRIC) hardware on board the second to the last flight of the Space Shuttle Discovery (STS-131 mission), we studied how microgravity impacts root growth in Arabidopsis thaliana. Ground-based studies showed that the actin cytoskeleton negatively regulates root gravity responses on Earth, leading us to hypothesise that actin might also be an important modulator of root growth behaviour in space. We investigated how microgravity impacted root growth of wild type (ecotype Columbia) and a mutant (act2-3) disrupted in a root-expressed vegetative actin isoform (ACTIN2). Roots of etiolated wild-type and act2-3 seedlings grown in space skewed vigorously toward the left, which was unexpected given the reduced directional cue provided by gravity. The left-handed directional root growth in space was more pronounced in act2-3 mutants than wild type. To quantify differences in root orientation of these two genotypes in space, we developed an algorithm where single root images were converted into binary images using computational edge detection methods. Binary images were processed with Fast Fourier Transformation (FFT), and histogram and entropy were used to determine spectral distribution, such that high entropy values corresponded to roots that deviated more strongly from linear orientation whereas low entropy values represented straight roots. We found that act2-3 roots had a statistically stronger skewing/coiling response than wild-type roots, but such differences were not apparent on Earth. Ultrastructural studies revealed that newly developed cell walls of space-grown act2-3 roots were more severely disrupted compared to space-grown wild type, and ground control wild-type and act2-3 roots. Collectively, our results provide evidence that, like root gravity responses on Earth, endogenous directional growth patterns of roots in microgravity are suppressed by the actin cytoskeleton. Modulation of root growth in space by actin could be facilitated in part through its impact on cell wall architecture.
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Affiliation(s)
- J Nakashima
- Division of Plant Biology, The Samuel Roberts Noble Foundation, Ardmore, OK, USA
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Mugnai S, Azzarello E, Baluska F, Mancuso S. Local root apex hypoxia induces NO-mediated hypoxic acclimation of the entire root. PLANT & CELL PHYSIOLOGY 2012; 53:912-920. [PMID: 22422934 DOI: 10.1093/pcp/pcs034] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Roots are very sensitive to hypoxia and adapt effectively to a reduced availability of oxygen in the soil. However, the site of the root where oxygen availability is sensed and how roots acclimate to hypoxia remain unclear. In this study, we found that the root apex transition zone plays central roles in both sensing and adapting to root hypoxia. The exposure of cells of the root apex to hypoxia is sufficient to achieve hypoxic acclimation of the entire root; particularly relevant in this respect is that, of the entire root apex, the transition zone cells show the highest demand for oxygen and also emit the largest amount of nitric oxide (NO). Local root apex-specific oxygen deprivation dramatically inhibits the oxygen influx peak in the transition zone and simultaneously stimulates a local increase in NO emission. The hypoxia-induced efflux of NO is strictly associated with the transition zone and is essential for hypoxic acclimation of the entire root.
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Affiliation(s)
- Sergio Mugnai
- LINV, Department of Plant, Soil and Environmental Science, University of Florence, Viale delle Idee 30, 50019 Sesto Fiorentino, FI, Italy
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Musgrave ME, Kuang A. Plant Reproductive Development during Spaceflight. DEVELOPMENTAL BIOLOGY RESEARCH IN SPACE 2003; 9:1-23. [PMID: 14631627 DOI: 10.1016/s1569-2574(03)09001-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Reproductive development in microgravity has now been studied in a variety of plants; Arabidopsis, Brassica, and Triticum have been especially well studied. Earlier indications that gravity might be required for some stage of reproductive development have now been refuted. Nevertheless, the spaceflight environment presents many unique challenges that have often compromised the ability of plants to reproduce. These include limitations in hardware design to compensate for the unique environmental characteristics of microgravity, especially absence of convective air movement. Pollen development has been shown to be sensitive to high concentrations of ethylene prevailing on various orbital platforms. Barring these gross environmental problems, androecium and gynoecium development occur normally in microgravity, in that functional propagules are produced. Nonetheless, qualitative changes in anther and pistil development have been shown, and significant qualitative changes occur in storage reserve deposition during seed development. Apart from the intrinsic biological importance of these results, consequences of diminished seed quality when plants are grown in the absence of gravity will detract from the utility of plant-based life support systems. By understanding gravity's role in determining the microenvironments that prevail during reproductive development, counter-measures to these obstacles can be found, while at the same time providing basic knowledge that will have broader agricultural significance.
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Affiliation(s)
- Mary E Musgrave
- Department of Plant Science, University of Connecticut, 1376 Storrs Road, Unit 4067, Storrs, CT 06269, USA.
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Abstract
NADPH oxidase is classically regarded as a key enzyme of neutrophils, where it is involved in the pathogenic production of reactive oxygen species. However, NADPH oxidase-like enzymes have recently been identified in non-neutrophil cells, supporting a separate role for NADPH-oxidase derived oxygen species in oxygen sensitive processes. This article reviews the current literature surrounding the potential role of NADPH oxidase in the oxygen sensing processes which underlie hypoxic pulmonary vasoconstriction, systemic vascular smooth muscle proliferation, carotid and airways chemoreceptor activation, erythropoietin gene expression, and oxytropic responses of plant cells.
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Affiliation(s)
- R D Jones
- Section of Respiratory Medicine, Academic Department of Medicine, The University of Hull, Hull, UK.
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