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Duan W, Chen X, Ding Y, Mao X, Song Z, Bao J, Fang L, Guo L, Zhou J. Intricate microbe-plant-metabolic remodeling mediated by intercropping enhances the quality of Panax quinquefolius L. PHYSIOLOGIA PLANTARUM 2024; 176:e14499. [PMID: 39221485 DOI: 10.1111/ppl.14499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 07/13/2024] [Accepted: 07/27/2024] [Indexed: 09/04/2024]
Abstract
Improving the cultivation mode and technology for traditional Chinese medicine has become important for its sustainable development. Monoculture enhances plant diseases, which decreases yield and quality. Intercropping is an effective measure to counterbalance that negative effect. In this study, we focused on Panax quinquefolium L. (ginseng) and four treatments were set up: the control without intercropping, P. quinquefolius + ryegrass (Lolium perenne L.), P. quinquefolius + red clover (Trifolium pratense L.), and P. quinquefolius + ryegrass + red clover. An LC-MS/MS system was used to detect the changes in the P. quinquefolius secondary metabolites, and high-throughput sequencing technology was used to determine the changes in the P. quinquefolius' rhizosphere soil microorganisms. Ginsenoside content, soil enzyme activities, and arbuscular mycorrhizal infection rate of P. quinquefolius were also measured using HPLC, ELISA kits, and microscopy, respectively. Co-intertia and Pearson's analysis were performed to explore the relationship between the metabolites and the P. quinquefolius microorganisms. Intercropping significantly increased the content of ginsenoside metabolites and recruited a large number of beneficial bacteria to the P. quinquefolius rhizosphere. The P. quinquefolius secondary metabolites were associated with the rhizosphere microbial community. For example, the dominant microorganisms, such as Acidobacteriota and Chloroflexi, played a key role in promoting the synthesis of ginsenoside Rd and (20R) ginsenoside Rg3 by P. quinquefolius. Intercropping led to changes in the P. quinquefolius secondary metabolites by driving and reshaping the rhizosphere microorganisms. These findings revealed the potential application of intercropping for improving the quality of P. quinquefolius.
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Affiliation(s)
- Wanying Duan
- School of Biological Science and Technology, University of Jinan, Jinan, P. R. China
- State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijng, P. R. China
| | - Xiaoli Chen
- School of Biological Science and Technology, University of Jinan, Jinan, P. R. China
| | - Yu Ding
- School of Biological Science and Technology, University of Jinan, Jinan, P. R. China
| | - Xinying Mao
- School of Biological Science and Technology, University of Jinan, Jinan, P. R. China
| | - Zhengjian Song
- Weihai (Wendeng) Authentic Ginseng Industry Development Co., Ltd., Wendeng, P. R. China
| | - Jie Bao
- School of Biological Science and Technology, University of Jinan, Jinan, P. R. China
| | - Lei Fang
- School of Biological Science and Technology, University of Jinan, Jinan, P. R. China
- Shandong Engineering Research Center of Key Technologies for High-Value and High-Efficiency Full Industry Chain of Lonicera japonica, Linyi, P. R. China
- Pingyi Fangyuan Pharmaceutical Co., Ltd., Linyi, P. R. China
| | - Lanping Guo
- State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijng, P. R. China
| | - Jie Zhou
- School of Biological Science and Technology, University of Jinan, Jinan, P. R. China
- State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, National Resource Center for Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijng, P. R. China
- Shandong Engineering Research Center of Key Technologies for High-Value and High-Efficiency Full Industry Chain of Lonicera japonica, Linyi, P. R. China
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Lei S, Yu G, Rossi S, Yu J, Huang B. LpNOL-knockdown suppression of heat-induced leaf senescence in perennial ryegrass involving regulation of amino acid and organic acid metabolism. PHYSIOLOGIA PLANTARUM 2021; 173:1979-1991. [PMID: 34455589 DOI: 10.1111/ppl.13541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/06/2021] [Accepted: 08/24/2021] [Indexed: 06/13/2023]
Abstract
The nonyellow COLORING 1-like gene (NOL) is known for its roles in accelerating leaf senescence, but the underlying metabolic mechanisms for heat-induced leaf senescence remain unclear. The objectives of this study were to identify metabolites and associated metabolic pathways regulated by knockdown of NOL in perennial ryegrass (Lolium perenne) and to determine the metabolic mechanisms of NOL controlling heat-induced leaf senescence. Wild-type (WT; cv. "Pinnacle") and two lines (Noli-1 and Noli-2) of perennial ryegrass with LpNOL knockdown were exposed to heat stress at 35/33°C (day/night) or nonstress control temperatures at 25/22°C (day/night) for 30 days in growth chambers. Leaf electrolyte leakage, chlorophyll (Chl) content, photochemical efficiency (Fv /Fm ), and net photosynthetic rate (Pn) were measured as physiological indicators of leaf senescence, while gas chromatography-mass spectrometry was performed to identify metabolites regulated by LpNOL. Knockdown of LpNOL suppressed heat-induced leaf senescence and produced a stay-green phenotype in perennial ryegrass, as manifested by increased Chl content, photochemical efficiency, net photosynthetic rate, and cell membrane stability in Noli-1 and Noli-2. Five metabolites (valine, malic acid, threonic acid, shikimic acid, chlorogenic acid) were uniquely upregulated in LpNOL plants exposed to heat stress, and six metabolites (aspartic acid, glutamic acid, 5-oxoproline, phenylalanine, proline, tartaric acid) exhibited more pronounced increases in their content in LpNOL plants than the WT. LpNOL could regulate heat-induced leaf senescence in perennial ryegrass through metabolic reprogramming in the pathways of respiration, secondary metabolism, antioxidant metabolism, and protein synthesis.
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Affiliation(s)
- Shuhan Lei
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
- Department of Plant Biology, Rutgers University, New Brunswick, New Jersey, USA
| | - Guohui Yu
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Stephanie Rossi
- Department of Plant Biology, Rutgers University, New Brunswick, New Jersey, USA
| | - Jinjing Yu
- College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China
| | - Bingru Huang
- Department of Plant Biology, Rutgers University, New Brunswick, New Jersey, USA
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AbdElgawad H, Abuelsoud W, Madany MMY, Selim S, Zinta G, Mousa ASM, Hozzein WN. Actinomycetes Enrich Soil Rhizosphere and Improve Seed Quality as well as Productivity of Legumes by Boosting Nitrogen Availability and Metabolism. Biomolecules 2020; 10:E1675. [PMID: 33333896 PMCID: PMC7765327 DOI: 10.3390/biom10121675] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 11/23/2020] [Accepted: 11/23/2020] [Indexed: 12/18/2022] Open
Abstract
The use of actinomycetes for improving soil fertility and plant production is an attractive strategy for developing sustainable agricultural systems due to their effectiveness, eco-friendliness, and low production cost. Out of 17 species isolated from the soil rhizosphere of legume crops, 4 bioactive isolates were selected and their impact on 5 legumes: soybean, kidney bean, chickpea, lentil, and pea were evaluated. According to the morphological and molecular identification, these isolates belong to the genus Streptomyces. Here, we showed that these isolates increased soil nutrients and organic matter content and improved soil microbial populations. At the plant level, soil enrichment with actinomycetes increased photosynthetic reactions and eventually increased legume yield. Actinomycetes also increased nitrogen availability in soil and legume tissue and seeds, which induced the activity of key nitrogen metabolizing enzymes, e.g., glutamine synthetase, glutamate synthase, and nitrate reductase. In addition to increased nitrogen-containing amino acids levels, we also report high sugar, organic acids, and fatty acids as well as antioxidant phenolics, mineral, and vitamins levels in actinomycete treated legume seeds, which in turn improved their seed quality. Overall, this study shed the light on the impact of actinomycetes on enhancing the quality and productivity of legume crops by boosting the bioactive primary and secondary metabolites. Moreover, our findings emphasize the positive role of actinomycetes in improving the soil by enriching its microbial population. Therefore, our data reinforce the usage of actinomycetes as biofertilizers to provide sustainable food production and achieve biosafety.
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Affiliation(s)
- Hamada AbdElgawad
- Botany and Microbiology Department, Faculty of Science, Beni-Suef University, Beni-Suef 62511, Egypt; (H.A.); (A.S.M.M.)
| | - Walid Abuelsoud
- Department of Botany and Microbiology, Faculty of Science, Cairo University, Giza 12613, Egypt; (W.A.); (M.M.Y.M.)
| | - Mahmoud M. Y. Madany
- Department of Botany and Microbiology, Faculty of Science, Cairo University, Giza 12613, Egypt; (W.A.); (M.M.Y.M.)
- Biology Department, College of Science, Taibah University, Al-Madinah Al-Munawarah 41411, Saudi Arabia
| | - Samy Selim
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Sakaka P.O. 2014, Saudi Arabia;
| | - Gaurav Zinta
- Shanghai Center for Plant Stress Biology, Center of Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China;
| | - Ahmed S. M. Mousa
- Botany and Microbiology Department, Faculty of Science, Beni-Suef University, Beni-Suef 62511, Egypt; (H.A.); (A.S.M.M.)
| | - Wael N. Hozzein
- Botany and Microbiology Department, Faculty of Science, Beni-Suef University, Beni-Suef 62511, Egypt; (H.A.); (A.S.M.M.)
- Bioproducts Research Chair, Zoology Department, College of Science, King Saud University, Riyadh 11451, Saudi Arabia
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Hassan MU, Islam MM, Wang R, Guo J, Luo H, Chen F, Li X. Glutamine application promotes nitrogen and biomass accumulation in the shoot of seedlings of the maize hybrid ZD958. PLANTA 2020; 251:66. [PMID: 32065312 DOI: 10.1007/s00425-020-03363-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 02/09/2020] [Indexed: 05/21/2023]
Abstract
Glutamine (Gln) is an efficient nitrogen source in promoting aboveground nitrogen and biomass accumulation in ZD958 (an elite maize hybrid with great potential for further genetic improvement) seedlings when conditioning a smaller but adequate root system. Amino acids account for a significant part of nitrogen (N) resources in the soil. However, how amino acid-N affects crop growth remains to be further investigated. Here, glutamine (Gln) application (80% NH4NO3 + 20% Gln; mixed N) enhanced shoot growth of the maize hybrid ZD958. N concentration in the shoot increased, which is associated with favorable increases in SPAD values, GS/GOGAT activities, and accumulation of glutamate, asparagine, total free amino acids and soluble proteins in the shoot under mixed N. On the other hand, root growth was reduced when exposed to Gln as indicated by the significantly lower dry weight, root/shoot ratio, and primary, seminal, crown, and total root lengths, as well as unfavorable physiological alterations. Up-regulation of expression of ZmAMT1.3, ZmNRT2.1, and ZmAAP2 in the root and that of ZmAMT1.1, ZmAMT1.3, and ZmLHT1 in the shoot preconditioned N over-accumulation in the shoot and facilitated shoot growth, presumably via enhancing N translocation to the shoot, when Gln was supplied. Together, Gln is an efficient N source in promoting aboveground N and biomass accumulation in ZD958 seedlings when conditioning a smaller but adequate root system. Notably, ZD958's parental lines Z58 and Chang7-2 displayed a wide range of variations in Gln responses, which may be partially attributed to single nucleotide polymorphisms (SNPs) in cis-elements and coding regions revealed in this study and much larger quantities of unidentified genetic variations between Z58 and Chang7-2. Extensive genetic divergence of these two elite inbred lines implied large potentials for further genetic improvement of ZD958 in relation to organic N use efficiency.
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Affiliation(s)
- Mahmood Ul Hassan
- The Key Laboratory of Plant-Soil Interactions, MOE, Beijing, 100193, China
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Md Monirul Islam
- The Key Laboratory of Plant-Soil Interactions, MOE, Beijing, 100193, China
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Ruifeng Wang
- The Key Laboratory of Plant-Soil Interactions, MOE, Beijing, 100193, China
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Jingyu Guo
- The Key Laboratory of Plant-Soil Interactions, MOE, Beijing, 100193, China
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Huilan Luo
- The Key Laboratory of Plant-Soil Interactions, MOE, Beijing, 100193, China
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Fanjun Chen
- The Key Laboratory of Plant-Soil Interactions, MOE, Beijing, 100193, China
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China
| | - Xuexian Li
- The Key Laboratory of Plant-Soil Interactions, MOE, Beijing, 100193, China.
- Department of Plant Nutrition, China Agricultural University, Beijing, 100193, China.
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Chu Q, Sha Z, Nakamura T, Oka N, Osaki M, Watanabe T. Differential Responses of Soybean and Sorghum Growth, Nitrogen Uptake, and Microbial Metabolism in the Rhizosphere to Cattle Manure Application: A Rhizobox Study. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2016; 64:8084-8094. [PMID: 27726362 DOI: 10.1021/acs.jafc.6b03046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In this study, we determined the capacity of soybean (Glycine max L. Merr. cv. Hoyoharuka) and sorghum (Sorghum bicolor L. Moench. cv. Hybrid Sorgo) to utilize different forms of nitrogen (N) in a rhizobox system. Seedlings were grown for 35 days without N or with 130 mg N kg-1 soil as ammonium sulfate or farmyard cattle manure. The soil fractions at different distances from the root were sliced millimeter by millimeter in the rhizobox system. We assessed the distribution of different forms of N and microbial metabolism in different soil fractions in the rhizosphere. There are no treatment-dependent changes in biomass production in the roots and shoots of soybeans, however, the ammonium and manure treatment yielded 1.30 and 1.40 times higher shoot biomass of sorghum than the control. Moreover, the depletion of inorganic N and total amino acids (TAA) in the rhizosphere was largely undetectable at various distances from the soybean roots regardless of the treatments employed. The addition of ammonium sulfate resulted in a decrease in the nitrate concentration gradient as the distance decreased from the sorghum roots. The addition of manure to the soil increased the N content in the sorghum shoots, 1.57 times higher than the control; this increase was negatively correlated with the concentrations of TAA in the soil of the root compartment. In addition, the application of manure simultaneously induced TAA depletion (i.e., the TAA concentration in root compartment was 1.48 times higher than that in bulk soil) and greater microbial activity and diversity in the sorghum rhizosphere, where higher microbial consumption of asparagine, glutamic acid, and phenylalanine were also observed near the roots. Our results are first to present the evidence that sorghum may possess a high capacity for taking up amino acids as a consequence of organic matter application, and microbial metabolism.
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Affiliation(s)
- Qingnan Chu
- Research Faculty of Agriculture, Hokkaido University , Kita-9, Nishi-9, Kitaku, Sapporo 060-8589, Japan
| | - Zhimin Sha
- School of Agriculture and Biology, Shanghai Jiaotong University , 200240 Shanghai, China
| | - Takuji Nakamura
- Hokkaido Agricultural Research Center, NARO , Sapporo 062-8555, Japan
| | - Norikuni Oka
- Hokkaido Agricultural Research Center, NARO , Sapporo 062-8555, Japan
| | - Mitsuru Osaki
- Research Faculty of Agriculture, Hokkaido University , Kita-9, Nishi-9, Kitaku, Sapporo 060-8589, Japan
| | - Toshihiro Watanabe
- Research Faculty of Agriculture, Hokkaido University , Kita-9, Nishi-9, Kitaku, Sapporo 060-8589, Japan
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Cao XC, Ma QX, Wu LH, Zhu LF, Jin QY. Effects of ammonium application rate on uptake of soil adsorbed amino acids by rice. J Zhejiang Univ Sci B 2016. [DOI: 10.1631/jzus.b1500203] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Brackin R, Näsholm T, Robinson N, Guillou S, Vinall K, Lakshmanan P, Schmidt S, Inselsbacher E. Nitrogen fluxes at the root-soil interface show a mismatch of nitrogen fertilizer supply and sugarcane root uptake capacity. Sci Rep 2015; 5:15727. [PMID: 26496834 PMCID: PMC4620560 DOI: 10.1038/srep15727] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 10/01/2015] [Indexed: 01/26/2023] Open
Abstract
Globally only ≈50% of applied nitrogen (N) fertilizer is captured by crops, and the remainder can cause pollution via runoff and gaseous emissions. Synchronizing soil N supply and crop demand will address this problem, however current soil analysis methods provide little insight into delivery and acquisition of N forms by roots. We used microdialysis, a novel technique for in situ quantification of soil nutrient fluxes, to measure N fluxes in sugarcane cropping soils receiving different fertilizer regimes, and compare these with N uptake capacities of sugarcane roots. We show that in fertilized sugarcane soils, fluxes of inorganic N exceed the uptake capacities of sugarcane roots by several orders of magnitude. Contrary, fluxes of organic N closely matched roots' uptake capacity. These results indicate root uptake capacity constrains plant acquisition of inorganic N. This mismatch between soil N supply and root N uptake capacity is a likely key driver for low N efficiency in the studied crop system. Our results also suggest that (i) the relative contribution of inorganic N for plant nutrition may be overestimated when relying on soil extracts as indicators for root-available N, and (ii) organic N may contribute more to crop N supply than is currently assumed.
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Affiliation(s)
- Richard Brackin
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Torgny Näsholm
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
| | - Nicole Robinson
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Stéphane Guillou
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Kerry Vinall
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Prakash Lakshmanan
- Sugar Research Australia, 50 Meiers Road, Indooroopilly, QLD 4068, Australia
| | - Susanne Schmidt
- School of Agriculture and Food Sciences, The University of Queensland, QLD, 4072, Australia
| | - Erich Inselsbacher
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE-901 83 Umeå, Sweden
- University of Vienna, Department of Geography and Regional Research, Vienna, AT-1090, Austria
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Perchlik M, Foster J, Tegeder M. Different and overlapping functions of Arabidopsis LHT6 and AAP1 transporters in root amino acid uptake. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:5193-204. [PMID: 25005136 PMCID: PMC4157705 DOI: 10.1093/jxb/eru278] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 05/22/2014] [Accepted: 05/29/2014] [Indexed: 05/09/2023]
Abstract
Plants acquire nitrogen in the form of amino acids from the soil, and transport proteins located in the plasma membrane of root cells are required for this process. It was found that the Arabidopsis lysine-histidine-like transporter LHT6 is expressed in root cells important for amino acid uptake, including the epidermis, root hairs, and cortex. Transport studies with lht6 mutants using high levels of amino acids demonstrated that LHT6 is in fact involved in amino acid uptake. To determine if LHT6 plays a role in nitrogen acquisition at soil amino acid concentrations, growth and uptake studies were performed with low levels of toxic amino acid analogues and radiolabelled amino acids, respectively. In addition, mutants of AAP1, another root amino acid transporter, and lht6/aap1 double mutants were examined. The results showed that LHT6 is involved in uptake of acidic amino acids, glutamine and alanine, and probably phenylalanine. LHT6 seems not to transport basic or other neutral amino acids, or, alternatively, other transporters might compensate for eliminated LHT6 function. Previous studies suggested that AAP1 only takes up amino acids at high concentrations; however, here it is demonstrated that the transporter functions in acquisition of glutamate and neutral amino acids when present at soil concentrations. When comparing the characterized root uptake systems, it appears that transporters both with overlapping substrate specificity and with preference for specific substrates are required to access the soil amino acid pool.
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Affiliation(s)
- Molly Perchlik
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Justin Foster
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
| | - Mechthild Tegeder
- School of Biological Sciences, Washington State University, Pullman, WA 99164, USA
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Lonhienne TGA, Trusov Y, Young A, Rentsch D, Näsholm T, Schmidt S, Paungfoo-Lonhienne C. Effects of externally supplied protein on root morphology and biomass allocation in Arabidopsis. Sci Rep 2014; 4:5055. [PMID: 24852366 PMCID: PMC4031471 DOI: 10.1038/srep05055] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 05/06/2014] [Indexed: 12/02/2022] Open
Abstract
Growth, morphogenesis and function of roots are influenced by the concentration and form of nutrients present in soils, including low molecular mass inorganic N (IN, ammonium, nitrate) and organic N (ON, e.g. amino acids). Proteins, ON of high molecular mass, are prevalent in soils but their possible effects on roots have received little attention. Here, we investigated how externally supplied protein of a size typical of soluble soil proteins influences root development of axenically grown Arabidopsis. Addition of low to intermediate concentrations of protein (bovine serum albumen, BSA) to IN-replete growth medium increased root dry weight, root length and thickness, and root hair length. Supply of higher BSA concentrations inhibited root development. These effects were independent of total N concentrations in the growth medium. The possible involvement of phytohormones was investigated using Arabidopsis with defective auxin (tir1-1 and axr2-1) and ethylene (ein2-1) responses. That no phenotype was observed suggests a signalling pathway is operating independent of auxin and ethylene responses. This study expands the knowledge on N form-explicit responses to demonstrate that ON of high molecular mass elicits specific responses.
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Affiliation(s)
- Thierry G. A. Lonhienne
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Yuri Trusov
- School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
| | - Anthony Young
- Plant Pathology Herbarium, Queensland Primary Industries and Fisheries, QLD, 4068, Australia
| | - Doris Rentsch
- Institute of Plant Sciences, University of Bern, 3013 Bern, Switzerland
| | - Torgny Näsholm
- Department of Forest Ecology and Management, and Department of Forest Genetics and Plant Physiology, SLU, SE-901 83 Umeå, Sweden
| | - Susanne Schmidt
- School of Agriculture and Food Sciences, The University of Queensland, St. Lucia, QLD, 4072, Australia
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Abstract
As a signalling molecule, glutamate is best known for its role as a fast excitatory neurotransmitter in the mammalian nervous system, a role that requires the activity of a family of ionotropic glutamate receptors (iGluRs). The unexpected discovery in 1998 that Arabidopsis thaliana L. possesses a family of iGluR-related (GLR) genes laid the foundations for an assessment of glutamate's potential role as a signalling molecule in plants that is still in progress. Recent advances in elucidating the function of Arabidopsis GLR receptors has revealed similarities with iGluRs in their channel properties, but marked differences in their ligand specificities. The ability of plant GLR receptors to act as amino-acid-gated Ca(2+) channels with a broad agonist profile, combined with their expression throughout the plant, makes them strong candidates for a multiplicity of amino acid signalling roles. Although root growth is inhibited in the presence of a number of amino acids, only glutamate elicits a specific sequence of changes in growth, root tip morphology, and root branching. The recent finding that the MEKK1 gene is a positive regulator of glutamate sensitivity at the root tip has provided genetic evidence for the existence in plants of a glutamate signalling pathway analogous to those found in animals. This short review will discuss the most recent advances in understanding glutamate signalling in roots, considering them in the context of previous work in plants and animals.
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Affiliation(s)
- Brian G Forde
- Centre for Sustainable Agriculture, Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4YQ, UK
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