ORCID Profile
0000-0001-5319-3844
Current Organisation
NSW Department of Primary Industries
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Publisher: Springer Berlin Heidelberg
Date: 2010
Publisher: Elsevier BV
Date: 2023
DOI: 10.1016/J.JENVMAN.2022.116745
Abstract: Colloidal phosphorus (P
Publisher: Springer US
Date: 08-11-2021
Publisher: Springer International Publishing
Date: 2019
Publisher: Public Library of Science (PLoS)
Date: 11-10-2016
Publisher: Springer Science and Business Media LLC
Date: 05-12-2023
Publisher: CSIRO Publishing
Date: 03-05-2021
DOI: 10.1071/FP20351
Abstract: There is increasing interest in understanding how the microbial communities on roots can be manipulated to improve plant productivity. Root systems are not homogeneous organs but are comprised of different root types of various ages and anatomies that perform different functions. Relatively little is known about how this variation influences the distribution and abundance of microorganisms on roots and in the rhizosphere. Such information is important for understanding how root–microbe interactions might affect root function and prevent diseases. This study tested specific hypotheses related to the spatial variation of bacterial and fungal communities on wheat (Triticum aestivum L.) and rice (Oryza sativa L.) roots grown in contrasting soils. We demonstrate that microbial communities differed significantly between soil type, between host species, between root types, and with position along the root axes. The magnitude of variation between different root types and along in idual roots was comparable with the variation detected between different plant species. We discuss the general patterns that emerged in this variation and identify bacterial and fungal taxa that were consistently more abundant on specific regions of the root system. We argue that these patterns should be measured more routinely so that localised root–microbe interactions can be better linked with root system design, plant health and performance.
Publisher: Oxford University Press (OUP)
Date: 12-2006
DOI: 10.1111/J.1574-6941.2006.00167.X
Abstract: The survival and effectiveness of a bioaugmentation strain in its target environment depend not only on physicochemical parameters in the soil but also on the physiological state of the inoculated organism. This study examined the effect of variations in inoculum pretreatment on the survival, metabolic activity (measured as rRNA content) and polycyclic aromatic hydrocarbon (PAH)-catabolic gene expression of Sphingobium yanoikuyae B1 in an aged PAH-contaminated soil. RNA denaturing gradient gel electrophoresis analysis showed stable colonization of PAH-contaminated soil by S. yanoikuyae B1 after four pretreatments (growth in complex or minimal medium, starvation, or acclimation to phenanthrene). By contrast, extractable CFUs decreased with time for all four treatments, and significantly faster for Luria Bertani-grown inocula, suggesting that these cells adhered strongly to soil particles while remaining metabolically active. Pretreatment of the inoculum had a dramatic effect on the expression of genes specific to the PAH-degradation pathway. The highest levels of bphC and xylE expression were seen for inocula that had been precultivated on complex medium, and degradation of PAHs was significantly enhanced in soils treated with these inocula. The results suggest that using complex media instead of minimal media for cultivating bioaugmentation inocula may improve the subsequent efficiency of contaminant biodegradation in the soil.
Publisher: Springer Singapore
Date: 22-08-2021
Publisher: Elsevier BV
Date: 11-2017
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR13043
Abstract: This study sought to quantify the influence of ‘carbon farming’ practices on soil carbon stocks, in comparison with conventional grazing and cropping, in northern New South Wales. The study had two components: assessment of impacts of organic amendments on soil carbon and biological indicators in croplands on Vertosols of the Liverpool Plains and assessment of the impact of grazing management on soil carbon in Chromosols of the Northern Tablelands. The organic amendment sites identified for the survey had been treated with manures, composts, or microbial treatments, while the conventional management sites had received only chemical fertilisers. The rotational grazing sites had been managed so that grazing was restricted to short periods of several days, followed by long rest periods (generally several months) governed by pasture growth. These were compared with sites that were grazed continuously. No differences in total soil carbon stock, or soil carbon fractions, were observed between sites treated with organic amendments and those treated with chemical fertiliser. There was some evidence of increased soil carbon stock under rotational compared with continuous grazing, but the difference was not statistically significant. Similarly, double-stranded DNA (dsDNA) stocks were not significantly different in either of the management contrasts, but tended to show higher values in organic treatments and rotational grazing. The enzymatic activities of β-glucosidase and leucine-aminopeptidase were significantly higher in rotational than continuous grazing but statistically similar for the cropping site treatments. Relative abundance and community structure, measured on a subset of the cropping sites, showed a higher bacteria : fungi ratio and provided evidence that microbial process rates were significantly higher in chemically fertilised sites than organic amendment sites, suggesting enhanced mineralisation of organic matter under conventional management. The higher enzyme activity and indication of greater efficiency of microbial populations on carbon farming sites suggests a greater potential to build soil carbon under these practices. Further research is required to investigate whether the indicative trends observed reflect real effects of management.
Publisher: Oxford University Press (OUP)
Date: 22-07-2021
Abstract: Certain soil microorganisms can improve plant growth, and practices that encourage their proliferation around the roots can boost production and reduce reliance on agrochemicals. The beneficial effects of the microbial inoculants currently used in agriculture are inconsistent or short-lived because their persistence in soil and on roots is often poor. A complementary approach could use root exudates to recruit beneficial microbes directly from the soil and encourage inoculant proliferation. However, it is unclear whether the release of common organic metabolites can alter the root microbiome in a consistent manner and if so, how those changes vary throughout the whole root system. In this study, we altered the expression of transporters from the ALUMINUM-ACTIVATED MALATE TRANSPORTER and the MULTIDRUG AND TOXIC COMPOUND EXTRUSION families in rice (Oryza sativa L.) and wheat (Triticum aestivum L.) and tested how the subsequent release of their substrates (simple organic anions, including malate, citrate, and γ-amino butyric acid) from root apices affected the root microbiomes. We demonstrate that these exudate compounds, separately and in combination, significantly altered microbiome composition throughout the root system. However, the root type (seminal or nodal), position along the roots (apex or base), and soil type had a greater influence on microbiome structure than the exudates. These results reveal that the root microbiomes of important cereal species can be manipulated by altering the composition of root exudates, and support ongoing attempts to improve plant production by manipulating the root microbiome.
Publisher: CSIRO Publishing
Date: 27-06-2022
DOI: 10.1071/FP22073
Abstract: Acid soils limit yields of many important crops including canola (Brassica napus), Australia’s third largest crop. Aluminium (Al3+) stress is the main cause of this limitation primarily because the toxic Al3+ present inhibits root growth. Breeding programmes do not target acid-soil tolerance in B. napus because genetic variation and convincing quantitative trait loci have not been reported. We conducted a genome-wide association study (GWAS) using the BnASSYST ersity panel of B. napus genotyped with 35 729 high-quality DArTseq markers. We screened 352 B. napus accessions in hydroponics with and without a toxic concentration of AlCl3 (12 μM, pH 4.3) for 12 days and measured shoot biomass, root biomass, and root length. By accounting for both population structure and kinship matrices, five significant quantitative trait loci for different measures of resistance were identified using incremental Al3+ resistance indices. Within these quantitative trait locus regions of B. napus, 40 Arabidopsis thaliana gene orthologues were identified, including some previously linked with Al3+ resistance. GWAS analysis indicated that multiple genes are responsible for the natural variation in Al3+ resistance in B. napus. The results provide new genetic resources and markers to enhance that Al3+ resistance of B. napus germplasm via genomic and marker-assisted selection.
Publisher: Springer Science and Business Media LLC
Date: 12-2018
Publisher: Microbiology Society
Date: 07-2011
Abstract: An anaerobic rod-shaped thermophile was isolated from a hydrothermal vent at Suiyo Seamount, Izu-Bonin Arc, western Pacific Ocean, and was named strain MN14 T . The rods were Gram-negative-staining, non-motile without flagella, 2–4 µm long and 0.5 µm wide, and ided by binary fission in the mid-exponential phase. The cells were surrounded by a sheath-like structure (toga) and occurred singly or in chains. Spheroids containing multiple cells were observed not only in the stationary phase, as previously observed for species of the order Thermotogales , but also from the early exponential phase. Transmission electron microscopy revealed that the peptidoglycan in rods partly disintegrated in the early growth phases and that the outer membrane of the spheroids was not completely lined with peptidoglycan. These findings suggested that the spheroids were formed from rods by the disintegration of peptidoglycan and subsequent inflation of the outer membrane. The spheroids eventually generated tiny cells in the periplasmic space, indicating a viviparous mode of proliferation in addition to binary fission. Strain MN14 T grew at 40–75 °C, pH 5.0–8.2 and with 0.25–5.20 % (w/v) NaCl, with optimal growth occurring at 68 °C, pH 6.8 and with 2.5 % NaCl. The shortest doubling time was 24 min, assuming that the strain propagated only by binary fission. Elemental sulfur enhanced growth, but was not essential. Thiosulfate was not an electron acceptor for growth. The strain was a chemo-organotroph that grew on yeast extract as the sole growth substrate. Tryptone and starch supported its growth in the presence of yeast extract. The G+C content of the genomic DNA was 31.7 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that this strain belonged to the genus Thermosipho . No significant DNA–DNA hybridization was observed between the genomic DNA of strain MN14 T and phylogenetically related species of the genus Thermosipho . Based on this evidence, strain MN14 T is proposed to represent a novel species, named Thermosipho globiformans sp. nov. The species epithet globiformans reflects the formation of multicellular and reproductive spheroids by the novel strain. The type strain of this species is MN14 T ( = JCM 15059 T = DSM 19918 T ).
Publisher: Springer Science and Business Media LLC
Date: 30-12-2012
Publisher: MDPI AG
Date: 22-06-2020
Abstract: Bacteria use quorum sensing signaling for cell-to-cell communication, which is also important for their interactions with plant hosts. Quorum sensing via N-acyl-homoserine lactones (AHLs) is important for successful symbioses between legumes and nitrogen-fixing rhizobia. Previous studies have shown that plant hosts can recognize and respond to AHLs. Here, we tested whether the response of the model legume Medicago truncatula to AHLs from its symbiont and other bacteria could be modulated by the abundance and composition of plant-associated microbial communities. Temporary antibiotic treatment of the seeds removed the majority of bacterial taxa associated with M. truncatula roots and significantly altered the effect of AHLs on nodule numbers, but lateral root density, biomass, and root length responses were much less affected. The AHL 3-oxo-C14-HSL (homoserine lactone) specifically increased nodule numbers but only after the treatment of seeds with antibiotics. This increase was associated with increased expression of the early nodulation genes RIP1 and ENOD11 at 24 h after infection. A 454 pyrosequencing analysis of the plant-associated bacteria showed that antibiotic treatment had the biggest effect on bacterial community composition. However, we also found distinct effects of 3-oxo-C14-HSL on the abundance of specific bacterial taxa. Our results revealed a complex interaction between plants and their associated microbiome that could modify plant responses to AHLs.
Publisher: Springer Science and Business Media LLC
Date: 26-10-2022
DOI: 10.1007/S11104-022-05756-Z
Abstract: Durum wheat is sensitive of acid soils because it lacks effective genes for Al 3+ tolerance. Previous research showed introgression of the TaMATE1B and TaALMT1 genes in idually increased the Al 3+ tolerance of durum wheat. Here we aimed to (a) combine the genes into a single durum line, (b) compare the various introgression lines and (c) establish the effectiveness of the introgressions in improving the acid soil tolerance in the field. Durum wheat lines homozygous for Al 3+ -tolerant alleles of TaMATE1B and TaALMT1 were crossed to develop a line that incorporated both genes. The parental cultivar, lines with the in idual genes and the line with both genes introgressed were screened for Al 3+ tolerance by hydroponic and soil cultures in a growth cabinet. The lines were also assessed for biomass production and grain yield in the field on acid soils. The durum wheat lines with the various Al 3+ -tolerance genes introgressed performed better based on root growth than Jandaroi, the parental cultivar, in both hydroponic and soil assays when grown in a cabinet. The various introgression lines were tolerant of acid soils compared to Jandaroi when grown in the field as assessed by shoot biomass and grain yield. The TaALMT1 and TaMATE1B genes improve the acid soil tolerance of durum wheat with indications that combining both genes is the most effective strategy. The various lines will be valuable to breeders who wish to enhance the acid soil tolerance of durum germplasm.
Publisher: Springer Science and Business Media LLC
Date: 02-12-2016
Publisher: Wiley
Date: 07-01-2021
DOI: 10.1111/PLB.13222
Abstract: Copper (Cu) pollution of agricultural land is a major threat to crop production. Exogenous chemical treatment is an easily accessible and rapid approach to remediate metal toxicity, including Cu toxicity in plants. We compared the effects of ascobin (ASC ascorbic acid:citric acid at 2:1) and glutathione (GSH) in mitigation of Cu toxicity in rice. Plants subjected to Cu stress displayed growth inhibition and biomass reduction, which were connected to reduced levels of chlorophylls, RWC, total phenolic compounds, carotenoids and Mg 2+ . Increased accumulation of ROS and malondialdehyde indicated oxidative stress in Cu‐stressed plants. However, application of ASC or GSH minimized the inhibitory effects of Cu stress on rice plants by restricting Cu 2+ uptake and improving mineral balance, chlorophyll content and RWC. Both ASC and GSH pretreatments reduced levels of ROS and malondialdehyde and improved activities of antioxidant enzymes, suggesting their roles in alleviating oxidative damage. A comparison on the effects of ASC and GSH under Cu stress revealed that ASC was more effective in restricting Cu 2+ accumulation (69.5% by ASC and 57.1% by GSH), Ca 2+ and Mg 2+ homeostasis, protection of photosynthetic pigments and activation of antioxidant defence mechanisms [catalase (110.4%), ascorbate peroxidase (76.5%) and guaiacol peroxidase (39.0%) by ASC, and catalase (58.9%) and ascorbate peroxidase (59.9%) by GSH] in rice than GSH, eventually resulting in better protection of ASC‐pretreated plants against Cu stress. In conclusion, although ASC and GSH differed in induction of stress protective mechanisms, both were effective in improving rice performance in response to Cu phytotoxicity.
No related grants have been discovered for Akitomo Kawasaki.