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1.
Background and aims
Plant-soil feedback may vary across host species and environmental gradients. The relative importance of these biotic versus abiotic drivers of feedback will determine the stability of plant and microbial communities across environments. If plant hosts are the main driver of soil microbial communities, plant-soil feedback may be stable across changing environments. However, if microbial communities vary with environmental gradients, feedback may also vary, limiting its capacity to predict plant distributions.Methods
We characterized arbuscular mycorrhizal (AM) fungi across tree plantations and a primary Neotropical rainforest. We then performed a plant-soil feedback pot experiment of AM fungi from these plantations on three plant species and related feedback and AM fungal communities in the field.Results
In the field, temporal and spatial variation in AM fungal composition was similar in magnitude to variation across plant host species. Composition of AM fungi in the pot experiment significantly differed from the field plots. Furthermore, differential feedback was explained by shifts in AM fungal composition only for one plant host species (Hyeronima alchorneoides) in the pot experiment.Conclusions
Natural AM fungal communities were temporally and spatially heterogeneous and AM fungal communities in the greenhouse did not reflect natural soils. These factors led to heterogeneous and unpredictable feedback responses, which suggests that applying greenhouse derived plant-soil feedback trends to predict plant coexistence in natural systems may be misleading.2.
Transient expression of recombinant tissue plasminogen activator (rt-PA) gene in cucurbit plants using viral vector 总被引:1,自引:0,他引:1
Vahid Jalali Javaran Alireza Shafeinia Mokhtar Jalali Javaran Esmaeil Ghasemi Gojani Malihe Mirzaee 《Biotechnology letters》2017,39(4):607-612
Objective
To use a transient expression system to express a truncated human tissue plasminogen activator (K2S) gene in cucurbit plants.Results
The recombinant tissue plasminogen activator protein (K2S form) was expressed in active form in cucurbit plants. Its molecular weight was 43 kDa. The plant-derived rt-PA was determined using goat anti-rabbit antibody by western blotting. Among the infected lines, the highest expression of rt-PA was 62 ng/100 mg per leaf tissue as measured by ELISA. The enzymatic activity of the plant-derived rt-PA was 0.8 IU/ml.Conclusions
The K25 form of rt-PA was expressed for the first time using the viral expression system. Plant-derived rt-PA showed similar potency to commercially-available PA.3.
Nirmalee Bhagya Wijayalath Hengodage Anna Liisa Ruotsalainen Annamari Markkola Hely Häggman 《Plant and Soil》2017,414(1-2):171-180
Aims
Root fungal relationships in forest understory may be affected by tree harvesting. Deschampsia flexuosa forms a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi functioning in nutrient uptake, and a more loose association with dark septate endophytic (DSE) fungi. We asked how harvesting affects fungal colonisations and whether DSE is more prone to change than AM.Methods
Deschampsia flexuosa plants were sampled close to a control or a cut tree after top-canopy harvesting in a primary successional site. Colonisations were studied using light microscopy. Shoot N%, vegetation cover and soil nutrients were determined.Results
Tree harvesting did not affect vegetation and soil parameters, except potassium (K+) increasing near cut trees. AM colonisation did not change, while DSE increased. Shoot N% increased with increasing DSE near cut trees. Hyaline septate (HSE) hyphae and soil K+ and magnesium (Mg2+) were positively correlated near control trees. Lichen cover and HSE correlated negatively.Conclusions
DSE colonisation increased but AM did not change after harvesting. Positive correlation of DSE with shoot N% near cut trees may suggest a role for DSE in favouring plant nitrogen uptake after disturbance in an open microsite. HSE may play a role in K+ and Mg2+ uptake.4.
Mai Kukumägi Ivika Ostonen Veiko Uri Heljä-Sisko Helmisaari Arno Kanal Olevi Kull Krista Lõhmus 《Plant and Soil》2017,414(1-2):265-280
Aims
Understanding the linkage of soil respiration (Rs) with forest development is essential for long-term C cycle models. We estimated the variation and temperature sensitivity (Q10 value) of Rs and its hetero-, (Rh) and autotrophic (Ra) components in relation to abiotic and biotic factors in Norway spruce stands of different ages, and the effect of trenching on microbial and soil characteristics.Methods
Trenching method was used to partition Rs into Rh and Ra. Ingrowth core method was used to estimate fine root production. Soil microbial biomass was measured using manometric respirometers.Results
Rs varied in differently aged stands demonstrating non-linear response to development stage. The variation of Rs was explained by changes in biotic factors rather than by changes in soil microclimate. Rh was more sensitive to Ts than Rs or Ra. After 4 years of trenching soil pH, N, SOM and dehydrogenase activity were significantly changed in trenched plots compared to control plots.Conclusions
Different Q10 values of Rh and Ra in stands of different ages indicate the importance of Rs partitioning. Trenching should be used during a limited number of years because of the possible changes in chemical characteristics of soil and in the activity of soil microbial community.5.
Molla F. Mengist Dan Milbourne Sheila Alves Mike J. McLaughlin Peter W. Jones Denis Griffin 《Plant and Soil》2018,427(1-2):139-148
Aims
We investigated whether density fractionation can be used to determine the distribution of organic phosphorus (OP) between free and mineral-associated soil organic matter (SOM).Methods
We performed density fractionations using sodium polytungstate solution (specific gravity 1.6 g cm?3) on 20 soils from UK semi-natural and pasture ecosystems, to obtain a light fraction (LF) and a heavy fraction (HF) for each soil. The fractions were quantified by weight, and analysed for organic carbon (OC), total N (TN), total P (TP), inorganic P (IP), and OP (by difference).Results
Good recoveries of soil mass (96%), OC and TN (both ~ 90%) were obtained, but recovery of OP only averaged 56%. The average P:C ratio of HF SOM exceeded that of LF SOM by a factor of six, greater than the factor of two obtained for TN:OC. For the soils studied, the elements of SOM were predominantly in the HF, with averages of 75% for C, 82% for N, and 90% for P.Conclusions
The incomplete recovery of OP demands further work. Nonetheless, the results show that HF SOM is much richer in P than LF SOM.6.
Thais Freitas da Silva Renata Estebanez Vollú Joana Montezano Marques Joana Falcão Salles Lucy Seldin 《Plant and Soil》2017,414(1-2):69-79
Background
The fungus Colletotrichum is a plant pathogen that causes the anthracnose disease, resulting in huge losses in various crops including the rose-scented geranium (Pelargonium graveolens). Although the bacterial community associated with plants has an important role in the establishment of plant diseases, little is known about what happens in P. graveolens.Aims
To increase the knowledge about the bacterial community associated with P. graveolens and its relationship with anthracnose disease symptoms.Methods
Quantitative PCR and high-throughput sequencing were combined to determine the presence of the fungus Colletotrichum and to reveal the bacterial communities associated with different plant parts – root, stem and leaf – and in the rhizosphere and bulk soil, and also to determine the respective bacterial communities associated with P. graveolens leaves symptomatic and asymptomatic for anthracnose disease.Results
The fungus Colletotrichum was detected in all plant parts and in the surrounding soil. Bacterial communities varied spatially in plants, and the disease symptoms also influenced the composition of the bacterial community. Abundances of operational taxonomic units (OTUs) assigned to the phylum Actinobacteria and to the genus Streptococcus were greatly increased in asymptomatic leaves.Conclusions
The bacterial community associated to geranium leaves responds to anthracnose symptoms.7.
César Nicolás Juan P. Almeida Magnus Ellström Adam Bahr Sharon E. Bone Nicholas P. Rosenstock John R. Bargar Anders Tunlid Per Persson Håkan Wallander 《Plant and Soil》2017,414(1-2):113-125
Background and aims
Mineralization of soil organic matter (SOM) constitutes a major carbon flux to the atmosphere. The carbon use efficiency (CUE) of the saprotrophic microorganisms mineralizing SOM is integral for soil carbon dynamics. Here we investigate how the CUE is affected by temperature, metabolic conditions, and the molecular complexity of the substrate.Methods
We incubated O-horizon soil samples (with either 13C–glucose or 13C–cellulose) from a boreal coniferous forest at 4, 9, 14, and 19 °C, and calculated CUEs based on the amount of 13C–CO2 and 13C–labelled microbial biomass produced. The effects of substrate, temperature, and metabolic conditions (representing unlimited substrate supply and substrate limitation) on CUE were evaluated.Results
CUE from metabolizing glucose was higher as compared to cellulose. A slight decrease in CUE with increasing temperature was observed in glucose amended samples (but only in the range 9–19 °C), but not in cellulose amended samples. CUE differed significantly with metabolic conditions, i.e. CUE was higher during unlimited growth conditions as compared to conditions with substrate limitation.Conclusions
We conclude that it is integral to account for both differences in CUE during different metabolic phases, as well as complexity of substrate, when interpreting temperature dependence on CUE in incubation studies.8.
Douglas Adams Weiler Sandro José Giacomini Sylvie Recous Leonardo Mendes Bastos Getúlio Elias Pilecco Guilherme Dietrich Celso Aita 《Plant and Soil》2018,429(1-2):213-225
Aims
Biological soil crusts (biocrusts) are soil-surface communities in drylands, dominated by cyanobacteria, mosses, and lichens. They provide key ecosystem functions by increasing soil stability and influencing soil hydrologic, nutrient, and carbon cycles. Because of this, methods to reestablish biocrusts in damaged drylands are needed. Here we test the reintroduction of field-collected vs. greenhouse-cultured biocrusts for rehabilitation.Methods
We collected biocrusts for 1) direct reapplication, and 2) artificial cultivation under varying hydration regimes. We added field-collected and cultivated biocrusts (with and without hardening treatments) to bare field plots and monitored establishment.Results
Both field-collected and cultivated cyanobacteria increased cover dramatically during the experimental period. Cultivated biocrusts established more rapidly than field-collected biocrusts, attaining ~82% cover in only one year, but addition of field-collected biocrusts led to higher species richness, biomass (as assessed by chlorophyll a) and level of development. Mosses and lichens did not establish well in either case, but late successional cover was affected by hardening and culture conditions.Conclusions
This study provides further evidence that it is possible to culture biocrust components from later successional materials and reestablish cultured organisms in the field. However, more research is needed into effective reclamation techniques.9.
Huan Fang Hu Zhou Gareth J. Norton Adam H. Price Annette C. Raffan Sacha J. Mooney Xinhua Peng Paul D. Hallett 《Plant and Soil》2018,424(1-2):233-254
Background and aims
Drought events, agricultural practices and plant communities influence microbial and soil abiotic parameters which can feedback to fodder production. This study aimed to determine which soil legacies influence plant biomass production and nutritional quality, and its resistance and recovery to extreme weather events.Methods
In a greenhouse experiment, soil legacy effects on Lolium perenne were examined, first under optimal conditions, and subsequently during and after drought. We used subalpine grassland soils previously cultivated for two years with grass communities of distinct functional composition, and subjected to combinations of climatic stress and simulated management.Results
The soil legacy of climatic stress increased biomass production of Lolium perenne and its resistance and recovery to a new drought. This beneficial effect resulted from higher nutrient availability in soils previously exposed to climatic stresses due to lower competitive abilities and resistance of microbial communities to a new drought. This negative effect on microbial communities was strongest in soils from previously cut and fertilized grasslands or dominated by conservative grasses.Conclusion
In subalpine grasslands more frequent climatic stresses could benefit fodder production in the short term, but threaten ecosystem functioning and the maintenance of traditional agricultural practices in the long term.10.
Cédric Gonneau Sanjay K. Mohanty Lee H. Dietterich Wei-Ting Hwang Jane K. Willenbring Brenda B. Casper 《Plant and Soil》2017,416(1-2):149-163
Background and aims
Elemental uptake in serpentine floras in eastern North America is largely unknown. The objective of this study was to determine major and trace element concentrations in soil and leaves of three native pseudo-metallophyte C4 grasses in situ at five sites with three very different soil types, including three serpentine sites, in eastern USA.Methods
Pseudo-total and extractible concentrations of 15 elements were measured and correlated from the soils and leaves of three species at the five sites.Results
Element concentrations in soils of pseudo-metallophytes varied up to five orders of magnitude. Soils from metalliferous sites exhibited higher concentrations of their characteristic elements than non-metalliferous. In metallicolous populations, elemental concentrations depended on the element. Concentrations of major elements (Ca, Mg, K) in leaves were lower than typical toxicity thresholds, whereas concentrations of Zn were higher.Conclusions
In grasses, species can maintain relatively low metal concentrations in their leaves even when soil concentrations are richer. However, in highly Zn-contaminated soil, we found evidence of a threshold concentration above which Zn uptake increases drastically. Finally, absence of main characteristics of serpentine soil at one site indicated the importance of soil survey and restoration to maintain serpentinophytes communities and avoid soil encroachment.11.
M. A. K. Mihoč L. Giménez-Benavides D. S. Pescador A. M. Sánchez L. A. Cavieres A. Escudero 《Plant and Soil》2016,408(1-2):31-41
Aims
Soil under nurse plants is more fertile than in the harsh surroundings. This is a primary mechanism involved in plant to plant facilitation and it is critical in structuring plant communities under stressful conditions. However we do not know how this soil enrichment process varies along complex environmental gradients and among coexisting nurse plants.Methods
Soil properties related to structure, resource stocks and microbial activity, were compared among up to ten nurse plant species and adjacent barren soil areas, along a 1600 m elevation gradient above the treeline in central Chilean Andes. Shifts in Relative Interaction Index (RII) sensu Armas (Ecology 85: 2682–2686, 2004) and in coefficient of variation on soil properties were also modelled.Results
Soil under nurse plants was always richer than on barren areas irrespective of altitude, except in the case of texture with more small particles in the intermediate altitude. β-glucosidase activity was higher under cushion plants than under nurse plants with other growth habit. Besides β-glucosidase and phosphatase activities were more variable at higher altitudes. Nitrogen was more variable under nurse plants than in barren areas and its RII values were lower at intermediate altitudes.Conclusions
Soil amelioration by nurse plants occurred all along the studied environmental gradient promoting islands of fertility and a general increase on soil niches heterogeneity.12.
Jonathan R. Gaiero Elizabeth Bent Tandra D. Fraser Leo M. Condron Kari E. Dunfield 《Plant and Soil》2018,427(1-2):39-51
Background and aims
Microbially driven mineralization of organic phosphorus forms is of particular importance in the soil environment, where it becomes available to plants as inorganic orthophosphates. In acidic soils, microbes produce non-specific acid phosphatases (NSAPs; E.C. 3.1.3.2) which act on the most common forms of organic P in the soil. Our understanding of phosphorus turnover in soils would greatly benefit from an improvement in research tools targeting these genes.Methods
Thus, in this study we developed two novel oligonucleotide PCR primer sets, that will enable researchers to target the present and active communities of bacteria with the genetic potential of acid phosphatase production. A total of three primer sets were validated to target the three classes of NSAPs. Utilizing Illumina MiSeq, amplicons from grassland pasture soils were sequenced.Results
The resulting target specificity was high for all three groups; CAAP (97.2%), CBAP (99.5%), and CCAP (94.8%). Quantification of target genes by qPCR indicated measurable differences between classes, ranging from 5 log to 7.5 log for CAAP, 6 log to 8 log for CBAP, and 4 log to 5 log for CCAP.Conclusions
The validated primer sets were specific to the target genes and identified potential quantitative differences between the NSAP classes.13.
Chao Xie Chin Lui Wesley Goi Daniel H. Huson Peter F. R. Little Rohan B. H. Williams 《BMC bioinformatics》2016,17(19):508
Background
Taxonomic profiling of microbial communities is often performed using small subunit ribosomal RNA (SSU) amplicon sequencing (16S or 18S), while environmental shotgun sequencing is often focused on functional analysis. Large shotgun datasets contain a significant number of SSU sequences and these can be exploited to perform an unbiased SSU--based taxonomic analysis.Results
Here we present a new program called RiboTagger that identifies and extracts taxonomically informative ribotags located in a specified variable region of the SSU gene in a high-throughput fashion.Conclusions
RiboTagger permits fast recovery of SSU-RNA sequences from shotgun nucleic acid surveys of complex microbial communities. The program targets all three domains of life, exhibits high sensitivity and specificity and is substantially faster than comparable programs.14.
Rachel A. Spicer Christoph Steinbeck 《Metabolomics : Official journal of the Metabolomic Society》2018,14(1):16
Introduction
Data sharing is being increasingly required by journals and has been heralded as a solution to the ‘replication crisis’.Objectives
(i) Review data sharing policies of journals publishing the most metabolomics papers associated with open data and (ii) compare these journals’ policies to those that publish the most metabolomics papers.Methods
A PubMed search was used to identify metabolomics papers. Metabolomics data repositories were manually searched for linked publications.Results
Journals that support data sharing are not necessarily those with the most papers associated to open metabolomics data.Conclusion
Further efforts are required to improve data sharing in metabolomics.15.
Bryan D. Emmett Daniel H. Buckley Margaret E. Smith Laurie E. Drinkwater 《Plant and Soil》2018,427(1-2):53-69
Background and aims
Phosphorus (P) availability is crucial for forest ecosystem productivity and soil organic matter (SOM) is an important source for P. This study was conducted to reveal carbon (C), nitrogen (N) and P distributions in functional SOM fractions. We hypothesised that (1) most of the organic P (Porg) is part of the particulate SOM, (2) particulate SOM stores increasing share of P with decreasing soil P content and (3) the C:Porg ratio of mineral-associated SOM is smaller than that of particulate SOM.Methods
We analysed soil samples from five temperate forest sites (Fagus sylvatica) under different geological parent material with a wide range of total P concentrations. Density fractionation was used to separate free light fraction (fLF), particulate SOM occluded within soil aggregates (occluded light fraction; oLF), and mineral associated SOM (heavy fraction; HF). We determined the mass balance of P in these fractions, in addition to the C and N concentrations. Additionally, the P speciation of the topsoil was analysed by X-ray absorption near edge structure (XANES) spectroscopy at the P K-edge.Results
The fLF contained 18–54% and the oLF 1–15% of total P (Ptot). High percentage of P in these light fractions was associated to soil minerals. Phosphorous in particulate SOM within aggregates tend to increase with decreasing soil P. The HF containing mineral-associated OM, comprised 38–71% of Ptot and their C:Porg ratios were consistently lower than those of the fLF irrespective of the P status of the soil.Conclusions
We show that all three functional SOM fractions contain variable amount of both organic and inorganic P species. The free light fraction shows no response to changing P stocks of soils.. Despite physically protected particulate SOM, oLF, becomes increasingly relevant as P cache in soils with declining P status.16.
Xinchang Kou Tongqing Su Ningning Ma Qi Li Peng Wang Zhengfang Wu Wenju Liang Weixin Cheng 《Plant and Soil》2018,422(1-2):129-134
Background
Seeds host bacterial inhabitants but only a limited knowledge is available on which taxa inhabit seed, which niches could be colonized, and what the routes of colonization are.Scope
Within this commentary, a discussion is provided on seed bacterial inhabitants, their taxa, and from where derive the seed colonizers.Conclusions
Seeds/and grains host specific bacteria deriving from the anthosphere, carposphere, or from cones of gymnosperms and inner tissues of plants after a long colonization from the soil to reproductive organs.17.
Background and Aims
The structures of arbuscular mycorrhizal (AM) fungi (hyphae, arbuscules, vesicles, spores) are used to make inferences about fungal activity based on stored samples, yet the impact of storage method has not been quantified, despite known effects of temperature and host condition on AM fungal colonisation.Methods
We measured how four storage treatments (cool or ambient conditions, with and without plant shoots attached, i.e. n?=?four treatment combinations) affected AM fungal colonisation of subterranean clover (Trifolium subterraneum L.) after 0, 2, 6 and 10 days of storage. Roots were assessed for colonisation of fine root endophyte and coarse AM fungi.Results
For coarse AM fungi, total colonisation was unaffected, but arbuscules were reduced at Day 6 and increased again by Day 10, except Ambient-Minus-Shoots. There was a loss of vesicles in all treatments at Day 2, and an increase in spore number at Day 6 within Cool-Plus-Shoots. In contrast, for fine root endophyte, total colonisation was greatly reduced at Day 6 but increased again at Day 10, in all except the Cool-Plus-Shoots treatment.Conclusions
Our data demonstrate that AM fungal activity is not suspended in commonly used plant storage conditions. Storage method and time impacted AM fungal colonisation, particularly for fine root endophyte. We recommend samples are processed within 2 days of harvest.18.
Background and aims
Variations in root-associated fungal communities contribute to the so-called ‘crop rotation benefit’ on soil productivity. We assessed the effects of chickpea, lentil, and pea in wheat-based rotations, as compared to wheat monoculture, on the structure of root-associated fungal communities, and described the legacy of pulses on a following wheat crop.Methods
The internal transcribed spacer (ITS) and 18S rRNA gene markers, and 454 amplicon pyrosequencing were used to describe the fungal communities of crop roots and rhizosphere soil in a field experiment and agronomic data were collected.Results
Pulses influenced only the structure of the non-mycorrhizal fungal community of roots. Fusarium tricinctum, Clonostachys rosea, Fusarium redolens, and Cryptococcus sp. were specific to certain crops. Despite the absence of selective effects of pulses on their associated arbuscular mycorrhizal (AM) fungal community, pea had a legacy effect on the structure of the AM fungal community associated with the roots of the following wheat crop, in one of the two year/sites examined. Species of Mortierella, Cryptococcus, and Paraglomus in wheat rhizosphere soil may benefit yield, whereas species of Fusarium, Davidiella, Lachnum, Sistotrema and Podospora may reduce yield.Conclusion
The effect of pulse crops on root fungal communities varied with rotation crop species. Pulses had various effects on the physiology of the following wheat crop, including increased productivity.19.
Tsafrir S. Mor 《Biotechnology letters》2015,37(11):2147-2150
Objectives
This short commentary examines the factors that led to Food and Drug Administration’s approval of the first plant-derived biologic.Results
In 2012, the first plant-derived protein pharmaceutical (biologic) was approved for commercial use in humans. The product, a recombinant form of human β-glucocerebrosidase marketed as ELELYSO, was developed by Protalix Biotherapeutics (Carmiel, Israel). The foresight to select this particular therapeutic product for development, flawless production pipeline, and serendipity seem to provide the key in explaining how ELELYSO became the first plant-derived biologic to achieve approval by Food and Drug Administration.Conclusions
While the circumstances that enabled Protalix and its scientists to become the first to arrive at this historic milestone are perhaps unique, it is anticipated that more biologics will follow suit in winning regulatory endorsement.20.