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Lawrie K. Brown Timothy S. George Konrad Neugebauer Philip J. White 《Plant and Soil》2017,412(1-2):115-132
Aims
Phosphorus (P) is frequently limiting crop production in agroecosystems. Large progress was achieved in understanding root traits associated with P acquisition efficiency (PAE, i.e. P uptake achieved under low P conditions). Most former studies were performed in controlled environments, and avoided the complexity of soil-root interactions. This may lead to an oversimplification of the root-soil relations. The aim of the present study was, therefore, to identify the dominant root and rhizosphere-related traits determining PAE, in contrasting soil conditions in the field.Methods
Twenty-three maize hybrids were grown at two contrasting P levels of a long-term P-fertilizer trial in two adjacent soil types: alkaline and neutral. Bulk soil, rhizosphere and root parameters were studied in relation to plant P acquisition.Results
Soil type had robust effect on PAE. Hybrids’ performance in one soil type was not related to that in the other soil type. In the neutral soil, roots exhibited higher specific root length, higher root/shoot ratio but lower PAE. Best performing hybrids in the neutral soil were characterized by top soil exploration, i.e., greater root surface and topsoil foraging. In contrast, in the alkaline soil, PAE and foraging traits were not correlated, P availability in the rhizosphere was greater than the bulk soil and phosphatase activity was higher, suggesting a ‘mining strategy’ in that case (i.e. traits that facilitate elevated P availability).Conclusions
These results indicate the key role of environmental factors for roots traits determining high PAE. The study highlights the need to consider soil properties when breeding for high PAE, as various soil types are likely to require different crop ideotypes.3.
S. L. Bauke M. Landl M. Koch D. Hofmann K. A. Nagel N. Siebers A. Schnepf W. Amelung 《Plant and Soil》2017,416(1-2):67-82
Background and aims
Macropores may be preferential root pathways into the subsoil. We hypothesised that the presence of macropores promotes P-uptake from subsoil, particularly at limited water supply in surface soil. We tested this hypothesis in a rhizotron experiment with spring wheat (Triticum aestivum cv. Scirocco) under variation of fertilisation and irrigation.Methods
Rhizotrons were filled with compacted subsoil (bulk density 1.4 g cm?3), underneath a P-depleted topsoil. In half of these rhizotrons the subsoil contained artificial macropores. Spring wheat was grown for 41 days with and without irrigation and 31P–addition. Also, a 33P–tracer was added at the soil surface to trace P-distribution in plants using liquid scintillation counting and radioactive imaging.Results
Fertilisation and irrigation promoted biomass production and plant P-uptake. Improved growing conditions resulted in a higher proportion of subsoil roots, indicating that the topsoil root system additionally promoted subsoil nutrient acquisition. The presence of macropores did not improve plant growth but tended to increase translocation of 33P into both above- and belowground biomass. 33P–imaging confirmed that this plant-internal transport of topsoil-P extended into subsoil roots.Conclusions
The lack of penetration resistance in macropores did not increase plant growth and nutrient uptake from subsoil here; however, wheat specifically re-allocated topsoil-P for subsoil root growth.4.
David A. Huskey Gilberto Curlango-Rivera Robert A. Root Fushi Wen Mary Kay Amistadi Jon Chorover Martha C. Hawes 《Plant and Soil》2018,430(1-2):205-217
Aims
Most plants produce a root tip extracellular matrix that includes viable border cell populations programmed to disperse into soil. Like neutrophils, border cells export structures that trap pathogens and prevent root tip infection. Border cells also trap metals. The goal of this study was to determine if border cells trap Pb.Methods
Border cell responses to Pb were observed microscopically. Border cell impact on Pb-induced injury to roots was assessed using root growth assays. Pb removal from solution was measured using inductively coupled plasma mass spectrometry (ICP-MS). Speciation of Pb associated with border cells was evaluated by synchrotron X-ray absorption spectroscopy (XAS).Results
Increased border cell trap size and number occurred within minutes in response to Pb but not silicon (Si). Transient immersion of root tips into Pb after border cells were removed resulted in growth inhibition. Immersion of root tips and border cells into Pb solution resulted in significant removal of Pb. Si levels in the presence of root tips remained unchanged. The Pb speciation, measured with Pb LIII XAS, altered when reacted with border cells, indicating that direct binding by extracellular traps occurred.Conclusions
Border cells can trap Pb and prevent damage to the root tip.5.
Marie J. Zwetsloot Johannes Lehmann Taryn Bauerle Steven Vanek Rachel Hestrin Abebe Nigussie 《Plant and Soil》2016,408(1-2):95-105
Aims
The objectives of this study were to evaluate (1) the fertilizer potential of bone char, (2) the effects of wood biochar on plant-available phosphorus (P), and (3) the role of root-mycorrhizae-biochar interactions in plant P acquisition from a P-fixing soil.Methods
Incubation and pot experiments were conducted with a P-fixing soil and maize with or without root hairs and arbuscular mycorrhizae (AM) inoculation. Olsen-, resin-P and plant P accumulation were used to estimate P availability from bone char, co-pyrolyzed bone char-wood biochar, and separate bone char and wood biochar additions produced at 60, 350 and 750 °C, and Triple Superphosphate (TSP).Results
Maize inoculated with AM showed similar P accumulation when fertilized with either 750 °C bone char or TSP. Pyrolyzing bone did not increase extractable P in soil in comparison to unpyrolyzed bone, apart from a 67 % increase in resin-extractable P after additions of bone char pyrolyzed at 350 °C. Despite greater Olsen-P extractability, co-pyrolysis of bone with wood reduced maize P uptake. Wood biochars reduced resin-P from bone char by 14–26 %, whereas oven-dried wood increased resin-P by 23 %.Conclusions
Bone char is an effective P fertilizer, especially if root-AM interactions are simultaneously considered. Biochar influences plant access to soil P and requires careful management to improve P availability.6.
Pei-Chun Lisa Hsu Maureen O’Callaghan Leo Condron Mark R. H. Hurst 《Plant and Soil》2018,425(1-2):43-55
Aims
The mechanisms by which rhizosphere bacteria increase the availability of mineral P precipitates for plant use are understudied. However, Paraburkholderia bryophila Ha185 is known to solubilize inorganic phosphate in vitro via a novel process. Therefore, this study aimed to demonstrate P solubilization by Ha185 in association with roots of perennial ryegrass (Lolium perenne L.).Methods
We developed a gnotobiotic plant assay to assess P solubilization by Ha185 on ryegrass roots under various nutrient conditions. A green fluorescent protein (GFP)-tagged derivative of Ha185 was used in conjunction with fluorescent microscopy and confocal microscopy to visualize colonization of ryegrass roots.Results
Ha185 solubilized mineral P (hydroxyapatite) in association with ryegrass roots and increased ryegrass growth by 20% under P-limited conditions. The GFP-tagged Ha185 strain colonized the rhizoplane and penetrated the primary root of ryegrass, possibly through “crack entry” at the point of lateral root emergence, but also by entering the epidermal cells via root hairs.Conclusions
Ha185 supported ryegrass growth under P-limited conditions, indicating this strain may improve availability of soil P for uptake by ryegrass. Tools developed in this study have broad application in the study of rhizobacteria-plant interactions.7.
Objective
To examine the activities of residual enzymes in dried shiitake mushrooms, which are a traditional foodstuff in Japanese cuisine, for possible applications in food processing.Results
Polysaccharide-degrading enzymes remained intact in dried shiitake mushrooms and the activities of amylase, β-glucosidase and pectinase were high. A potato digestion was tested using dried shiitake powder. The enzymes reacted with potato tuber specimens to solubilize sugars even under a heterogeneous solid-state condition and that their reaction modes were different at 38 and 50 °C.Conclusion
Dried shiitake mushrooms have a potential use in food processing as an enzyme preparation.8.
Minggang Wang Arjen Biere Wim H. van der Putten T. Martijn Bezemer E. Pernilla Brinkman 《Plant and Soil》2017,412(1-2):215-233
Aims
A soil-plant-atmosphere continuum (SPAC) model for simulating tree transpiration (Ep) with variable water stress and water distribution in the soil is presented. The model couples a sun/shade approach for the canopy with a discrete representation of the soil in different layers and compartments.Methods
To test its performance, the outputs from the simulations are compared to those from an experiment using trees of olive ‘Picual’ and almond ‘Marinada’ with the root system split into two. Trees are subjected to different irrigation phases in which one side of the root system is dried out while the other is kept wet.Results
The model is able to accurately predict Ep (R2 and the efficiency factor (EF) around 0.9) in the two species studied. The use of a function that modulates the uptake capacity of a root according to the soil water content was necessary to track the fluxes observed from each split part. It was also appropriate to account for root clumping to match the measured and modelled leaf water potential.Conclusions
Coupling the sun/shade approach with the soil multi-compartment solution provides a useful tool to explore tree Ep for different degrees of water availability and distribution.9.
Robert P. Jeffery Richard J. Simpson Hans Lambers Daniel R. Kidd Megan H. Ryan 《Plant and Soil》2017,412(1-2):21-34
Aims
Trifolium subterraneum L. is the predominant annual pasture legume in southern Australia. Cultivars with improved phosphorus (P) foraging ability would improve the P-use efficiency of agricultural systems. We therefore investigated variation in root traits related to P-uptake among six cultivars.Methods
Micro-swards were grown at six levels of P in field soil with indigenous arbuscular mycorrhizal (AM) fungi for six weeks. Dry matter yield, tissue P concentration, rhizosphere carboxylates, AM fungal colonisation and root morphological traits were measured.Results
The cultivars showed similar shoot and root yield responses to P supply. Average root diameter did not change, specific root length (SRL) increased and root tissue density (RTD) decreased with increased P supply. Amounts of total rhizosphere carboxylates were low (<1.2 nmol cm?1 root). The percentage of root length colonised by AM fungi was greatest (29–43 %) at an intermediate level (8 mg kg?1 dry soil) of P supply.Conclusions
Most differences among cultivars were reasonably consistent across P supply levels, indicating greater numbers of lines could be screened reliably at a single P level. Low colonisation by AM fungi at low P supply deserves consideration when selecting soils for cultivar comparisons. Increased SRL and decreased RTD at high P supply likely result from self-shading within the micro-swards and warrant further investigation.10.
Heidi A. Waddell Richard J. Simpson Megan H. Ryan Hans Lambers Denys L. Garden Alan E. Richardson 《Plant and Soil》2017,412(1-2):7-19
Aims
Rytidosperma species are native Australian grasses which have different growth rates and phosphorus (P) requirements. This study examined the role of root morphology traits in response to P supply.Methods
Nine Rytidosperma species ranging from slow- to fast-growth were examined along with Lolium perenne and Bromus hordeaceus. Plants were grown in a glasshouse for 47 days in soil supplied with six levels of P between 0 and 60 mg P per pot. Root mass, length and diameter, root hair length and density, and extent of mycorrhizal colonisation were measured.Results
Across all species there was a positive correlation (P < 0.001) between P uptake and root mass, length and root hair cylinder volume (RHCV; estimated using root diameter, root hair length and root length) at all levels of P supply. An exception was the RHCV of B. hordeaceus, where expected P uptake was not achieved due to a markedly reduced root length at low-P supply. For the Rytidosperma species, morphological plasticity for specific root length, root mass fraction and root hair length ranged from 1.5-fold to 2.7-fold between high- and low-P supply. However, across all species and P levels no single root morphological trait was identified for universally increasing the size of the root system and P uptake.Conclusions
Fast-growing species took up more P as a result of an overall larger root mass, greater root length and larger RHCV.11.
Zinc uptake by roots and accumulation in maize plants as affected by phosphorus application and arbuscular mycorrhizal colonization 总被引:1,自引:0,他引:1
Wei Zhang Xiu-Xiu Chen Yu-Min Liu Dun-Yi Liu Xin-Ping Chen Chun-Qin Zou 《Plant and Soil》2017,413(1-2):59-71
Background and aims
Phosphorus (P) application reduces the zinc (Zn) concentration of cereal grain, but the mechanisms, including root Zn accumulation, remain controversial.Methods
Field and pot experiments were conducted to determine the degree to which root Zn accumulation, root arbuscular mycorrhizal (AM) colonization, and other factors contribute to the negative interaction between P and Zn.Results
Root Zn accumulation was positively related to shoot Zn accumulation. In responding to P application, root Zn accumulation was more affected by changes in AM colonization than by changes in root dry weight (RDW). In the pot experiment without Zn supply, root Zn concentration (RZnC), RDW, and AM colonization together explained 98% (adjusted R2 value) of the decrease in root Zn accumulation with P application, while AM colonization and RDW explained 66% (adjusted R2 value) of decrease in total Zn accumulation. In the pot experiment with Zn sufficient supply, RZnC and RDW explained 89% (adjusted R2 value) of the decrease in root Zn accumulation with increasing P application, while RDW, RZnC, and AM colonization explained 53% (adjusted R2 value) of the decrease in total Zn accumulation.Conclusion
Especially in Zn-deficient soil, root Zn accumulation explains much of the negative interaction between P and Zn, and root Zn accumulation is greatly affected by AM colonization.12.
Oliver Bühler Morten Ingerslev Simon Skov Erik Schou Iben Margrete Thomsen Christian Nørgaard Nielsen Palle Kristoffersen 《Plant and Soil》2017,413(1-2):29-44
Aims
The purpose of this study is to evaluate root and stem growth, nutrient status and soil properties of a tree planting in structural soil.Methods
Root and stem growth were measured at an 10-year-old urban planting of Tilia x europaea L. ‘Pallida’ established in structural soil on a paved square in Copenhagen, Denmark.Root abundance was quantified and soil profiles were established at three different distances from 10 trees (1.0, 1.9, and 2.9 m). Soil and leaf samples were analysed for nutrient concentrations.Results
Abundant root presence was measured across the entire profile of structural soil (160?×?60 cm) at all distances, provided that structural soil layers were constructed correctly. Erroneously constructed structural soil layers however, resulted in impaired tree and root growth. Coarse root morphology was affected by the confined growing space in the voids of the stone matrix. The soil was relatively alkaline with an average pH (CaCl2) of 7.3. Foliar analysis revealed deficiencies of K and Mn. These deficiencies might be due to a combined effect of high pH and low soil concentrations of these nutrients.Conclusions
The study documents that correctly constructed structural soils allow and encourage root growth in load bearing layers.13.
Gabriella Saviano Debora Paris Dominique Melck Antonio Falasca Dalila Trupiano Maria Iorizzi Gabriella S. Scippa Andrea Motta 《Metabolomics : Official journal of the Metabolomic Society》2016,12(4):65
Introduction
Molecular factors are differentially observed in various bent sectors of poplar (Populus nigra) woody taproots. Responses to stress are modulated by a complex interplay among different hormones and signal transduction pathways. In recent years, metabolomics has been recognized as a powerful tool to characterize metabolic network regulation, and it has been widely applied to investigate plant responses to biotic and abiotic stresses.Objectives
In this paper we used metabolomics to understand if long term-bending stress induces a “spatial” and a “temporal” metabolic reprogramming in woody poplar roots.Methods
By NMR spectroscopy and statistical analysis we investigated the unstressed and three portions of stressed root (above-bent, bent, and below-bent) sectors collected at 12 (T0), 13 (T1) and 14 (T2) months after stress induction.Results
The data indicate a clear between-class separation of control and stressed regions, based on the metabolites regulation, during both spatial and temporal changes. We found that taproots, as a consequence of the stress, try to restore homeostasis and normal metabolic fluxes thorough the synthesis and/or accumulation of specific compounds related to mechanical forces distribution along the bent taproot.Conclusion
The data demonstrate that the impact of mechanical stress on plant biology can efficiently be studied by NMR-based metabolomics.14.
Gustavo Boitt Amanda Black Steve A. Wakelin Richard W. McDowell Leo M. Condron 《Plant and Soil》2018,427(1-2):163-174
Aims
We assessed and quantified the cumulative impact of 20 years of biomass management on the nature and bioavailability of soil phosphorus (P) accumulated from antecedent fertiliser inputs.Methods
Soil (0–2.5, 2.5–5, 5–10 cm) and plant samples were taken from replicate plots in a grassland field experiment maintained for 20 years under contrasting plant biomass regimen- biomass retained or removed after mowing. Analyses included dry matter production and P uptake, root biomass, total soil carbon (C), total nitrogen (N), total P, soil P fractionation, and 31P NMR spectroscopy.Results
Contemporary plant production and P uptake were over 2-fold higher for the biomass retained compared with the biomass removed regimes. Soil C, total P, soluble and labile forms of inorganic and organic soil P were significantly higher under biomass retention than removal.Conclusions
Reserves of soluble and labile inorganic P in soil were significantly depleted in response to continued long-term removal of P in plant biomass compared to retention. However, this was only sufficient to sustain plant production at half the level observed for the biomass retention after 20 years, which was partly attributed to limited mobilisation of organic P in response to P removal.15.
Background
An influenza H3N2 epidemic occurred throughout Southern China in 2012.Methods
We analyzed the hemagglutinin (HA) and neuraminidase (NA) genes of influenza H3N2 strains isolated between 2011–2012 from Guangdong. Mutation sites, evolutionary selection, antigenic sites, and N-glycosylation within these strains were analyzed.Results
The 2011–2012 Guangdong strains contained the HA-A214S, HA-V239I, HA-N328S, NA-L81P, and NA-D93G mutations, similar to those seen in the A/ Perth/16/2009 influenza strain. The HA-NSS061–063 and NNS160–162 glycosylation sites were prevalent among the 2011–2012 Guangdong strains but the NA-NRS402–404 site was deleted. Antigenically, there was a four-fold difference between A/Perth/16/2009 -like strains and the 2011–2012 Guangdong strains.Conclusion
Antigenic drift of the H3N2 subtype contributed to the occurrence of the Southern China influenza epidemic of 2012.16.
Claudio Inostroza-Blancheteau Franklin Magnum de Oliveira Silva Fabiola Durán Jaime Solano Toshihiro Obata Mariana Machado Alisdair R. Fernie Marjorie Reyes-Díaz Adriano Nunes-Nesi 《Metabolomics : Official journal of the Metabolomic Society》2018,14(10):138
Introduction
The native potatoes (Solanum tuberosum ssp. tuberosum L.) cultivated on Chiloé Island in southern Chile have great variability in terms of tuber shape, size, color and flavor. These traits have been preserved throughout generations due to the geographical position of Chiloé, as well as the different uses given by local farmers.Objectives
The present study aimed to investigate the diversity of metabolites in skin and pulp tissues of eleven native accessions of potatoes from Chile, and evaluate the metabolite associations between tuber tissues.Methods
For a deeper characterization of these accessions, we performed a comprehensive metabolic study in skin and pulp tissues of tubers, 3 months after harvesting. Specific targeted quantification of metabolites using 96 well microplates, and high-performance liquid chromatography combined with non-targeted metabolite profiling by gas chromatography time-of-flight mass spectrometry were used in this study.Results
We observed differential levels of antioxidant activity and phenolic compounds between skin and pulp compared to a common commercial cultivar (Desireé). In addition, we uncovered considerable metabolite variability between different tuber tissues and between native potatoes. Network correlation analysis revealed different metabolite associations among tuber tissues that indicate distinct associations between primary metabolite and anthocyanin levels, and antioxidant activity in skin and pulp tissues. Moreover, multivariate analysis lead to the grouping of native and commercial cultivars based on metabolites from both skin and pulp tissues.Conclusions
As well as providing important information to potato producers and breeding programs on the levels of health relevant phytochemicals and other abundant metabolites such as starch, proteins and amino acids, this study highlights the associations of different metabolites in tuber skins and pulp, indicating the need for distinct strategies for metabolic engineering in these tissues. Furthermore, this study shows that native Chilean potato accessions have great potential as a natural source of phytochemicals.17.
Ryunosuke Tateno Takeshi Taniguchi Jian Zhang Wei-Yu Shi Jian-Guo Zhang Sheng Du Norikazu Yamanaka 《Plant and Soil》2017,420(1-2):209-222
Aims
The objective of this study was to investigate how plants maintain productivity under a limited supply of water and N along the topographical soil water and N gradients in semi-arid forests.Methods
We investigated forest structure and productivity, N cycling, and water and N use by plants at three different slope positions in a forested area near an arid boundary on a loess plateau in China.Results
Net primary production (NPP) and aboveground N uptake decreased as soil water and/or N availability decreased on upper slopes; however, NPP and aboveground N uptake were only slightly lower than those of more humid forest ecosystems. Water use efficiency (WUE), N use efficiency (NUE), and fine root biomass increased as soil water and/or N supply decreased with altitude. High NUE was linked to higher N mean residence time, caused by higher N resorption efficiency rather than increasing N productivity.Conclusions
Our results suggest that NPP and N uptake can be maintained by increasing WUE and NUE and increasing fine root biomass in water and N co-limited semi-arid forest ecosystems near arid boundaries. Such changes in resource use and acquisition strategy can affect production and N cycling via plant-soil feedback systems.18.
Hans Lambers Felipe Albornoz Lukasz Kotula Etienne Laliberté Kosala Ranathunge François P. Teste Graham Zemunik 《Plant and Soil》2018,424(1-2):11-33
Background
Mycorrhizal strategies are very effective in enhancing plant acquisition of poorly-mobile nutrients, particularly phosphorus (P) from infertile soil. However, on very old and severely P-impoverished soils, a carboxylate-releasing and P-mobilising cluster-root strategy is more effective at acquiring this growth-limiting resource. Carboxylates are released during a period of only a few days from ephemeral cluster roots. Despite the cluster-root strategy being superior for P acquisition in such environments, these species coexist with a wide range of mycorrhizal species, raising questions about the mechanisms contributing to their coexistence.Scope
We surmise that the coexistence of mycorrhizal and non-mycorrhizal strategies is primarily accounted for by a combination of belowground mechanisms, namely (i) facilitation of P acquisition by mycorrhizal plants from neighbouring cluster-rooted plants, and (ii) interactions between roots, pathogens and mycorrhizal fungi, which enhance the plants’ defence against pathogens. Facilitation of nutrient acquisition by cluster-rooted plants involves carboxylate exudation, making more P available for both themselves and their mycorrhizal neighbours. Belowground nutrient exchanges between carboxylate-exuding plants and mycorrhizal N2-fixing plants appear likely, but require further experimental testing to determine their nutritional and ecological relevance. Anatomical studies of roots of cluster-rooted Proteaceae species show that they do not form a complete suberised exodermis.Conclusions
The absence of an exodermis may well be important to rapidly release carboxylates, but likely lowers root structural defences against pathogens, particularly oomycetes. Conversely, roots of mycorrhizal plants may not be as effective at acquiring P when P availability is very low, but they are better defended against pathogens, and this superior defence likely involves mycorrhizal fungi. Taken together, we are beginning to understand how an exceptionally large number of plant species and P-acquisition strategies coexist on the most severely P-impoverished soils.19.
Aim
Our objectives were to compare effects of root charge properties on Al adsorption by the roots of rice that differed in Al-tolerance, and to examine effects of different nitrogen forms on charge properties of rice roots and Al adsorption.Methods
Streaming potential and chemical methods were used to measure root zeta potential and investigate Al chemical forms adsorbed on the roots of rice obtained from solution culture experiments.Results
Rice roots of the Al-sensitive variety Yangdao-6 carried greater negative charge than the Al-tolerant variety Wuyunjing-7, which meant the roots of Yangdao-6 adsorbed more exchangeable and complexed Al. When both rice varieties were grown in NH4 +-containing nutrient solutions, there were less functional groups and lower negative surface charge on their roots, which reduced Al adsorption compared to the rice grown in NO3 ? containing nutrient solutions. The decline in nutrient solution pH due to NH4 + uptake by rice roots was responsible for the reduced numbers of functional groups and the lower negative surface charge on the roots compared to the rice grown in NO3 ? containing solutions.Conclusions
Integrated root surface charge, as expressed by zeta potential, played an important role in Al adsorption by the roots of rice with different Al-tolerance.20.
Elliott J. Price Ranjana Bhattacharjee Antonio Lopez-Montes Paul D. Fraser 《Metabolomics : Official journal of the Metabolomic Society》2017,13(11):144