Papers by Catherine Tétard-Jones
Herbicide tolerance in crops and weeds is considered to be monotrophic, i.e. determined by the re... more Herbicide tolerance in crops and weeds is considered to be monotrophic, i.e. determined by the relative susceptibility of the physiological process targeted and the plant’s ability to metabolise and detoxify the agrochemical. A growing body of evidence now suggests that endophytes, microbes that inhabit plant tissues and provide a range of growth, health and defence enhancements, can contribute to other types of abiotic and biotic stress tolerance. The current evidence for herbicide tolerance being bitrophic, with both free-living and plant-associated endophytes contributing to tolerance in the host plant, has been reviewed. We propose that endophytes can directly contribute to herbicide detoxification through their ability to metabolise xenobiotics. In addition, we explore the paradigm that microbes can ‘prime’ resistance mechanisms in plants such that they enhance herbicide tolerance by inducing the host’s stress responses to withstand the downstream toxicity caused by herbicides. This latter mechanism has the potential to contribute to the growth of non-target-site-based herbicide resistance in weeds. Microbial endophytes already contribute to herbicide detoxification in planta, and there is now significant scope to extend these interactions using synthetic biology approaches to engineer new chemical tolerance traits into crops via microbial engineering.
There is increasing concern about the sustainability and environmental impacts of mineral fertili... more There is increasing concern about the sustainability and environmental impacts of mineral fertilizer use in agriculture. Increased recycling of nutrients via the use of animal and green manures and fertilizers made from domestic organic waste may reduce reliance on mineral fertilizers. However, the relative availability of nutrients (especially nitrogen) is lower in organic compared to mineral fertilizers, which can result in significantly lower yields in nutrient demanding crops such as potato. It is therefore important to gain a better understanding of the factors affecting nutrient use efficiency (yield per unit fertilizer input) from organic fertilizers. Here we show that (a) previous crop management (organic vs. conventional fertilization and crop protection regimes), (b) organic fertilizer type and rate (composted cattle manure vs. composted chicken manure pellets) and (c) watering regimes (optimized and restricted) significantly affected leaf chlorophyll content, potato tuber N-concentration, proteome and yield. Protein inference by gel matching indicated several functional groups significantly affected by previous crop management and organic fertilizer type and rate, including stress/defense response, glycolysis and protein destination and storage. These results indicate genomic pathways controlling crop responses (nutrient use efficiency and yield) according to contrasting types OPEN ACCESS Agronomy 2013, 3 60 and rates of organic fertilizers that can be linked to the respective encoding genes.
The American Naturalist, 2007
PLoS ONE, 2012
Plants simultaneously interact with a plethora of species both belowground and aboveground, which... more Plants simultaneously interact with a plethora of species both belowground and aboveground, which can result in indirect effects mediated by plants. Studies incorporating plant genetic variation indicate that indirect effects mediated by plants may be a significant factor influencing the ecology and evolution of species within a community. Here, we present findings of a Quantitative Trait Locus (QTL) mapping study, where we mapped a rhizobacteria-aphid indirect effect onto the barley genome. We measured the size of aphid populations on barley when the barley rhizosphere either was or was not supplemented with a rhizobacterial species. Using a QTL mapping subset, we located five regions of the barley genome associated with the rhizobacteria-aphid indirect effect. Rhizobacterial supplementation led to an increase in aphid population size (mapped to three barley QTL), or a decrease in aphid population size (mapped to two barley QTL). One QTL associated with plant resistance to aphids was affected by a significant QTL-by-environment interaction, because it was not expressed when rhizobacteria was supplemented. Our results indicated that rhizobacterial supplementation of barley roots led to either increased or reduced aphid population size depending on plant genotype at five barley QTL. This indicates that the direction of a rhizobacteria-aphid indirect effect could influence the selection pressure on plants, when considering species that affect plant fitness. Further research may build on the findings presented here, to identify genes within QTL regions that are involved in the indirect interaction.
Philosophical Transactions of the Royal Society B: Biological Sciences, 2011
NJAS - Wageningen Journal of Life Sciences, 2011
Phenotypic plasticity in plants is a naturally occurring phenomenon that plants have evolved to s... more Phenotypic plasticity in plants is a naturally occurring phenomenon that plants have evolved to survive environmental change. In agriculture, environmental stress such as insect infestation can lead to reduction in yield components. Although insect resistance can be bred into crops, insect genetic variation can cause variability in resistance leading to yield reduction. However, the extent to which insect resistance is
Quantitative proteomics to study the response of potato to contrasting fertilisation regimes
Molecular Breeding, 2013
ABSTRACT There is concern over the sustainability and environmental impact of mineral fertilisers... more ABSTRACT There is concern over the sustainability and environmental impact of mineral fertilisers and crop protection inputs used in intensive arable crop production systems. However, replacing mineral with organic fertilisers (animal and green manures) and restricting the use of chemosynthetic crop protection may significantly reduce crop yields. The effects of (a) replacing mineral with composted cattle manure fertiliser input and (b) omitting pesticide-based crop protection on potato (Solanum tuberosum) tuber yield, leaf and tuber mineral nutrient content and leaf protein profiles were investigated. Switching to organic fertiliser had a greater effect on yield and protein profiles than the omission of chemosynthetic crop protection. Leaf N and P composition were significant drivers of protein expression, particularly proteins involved in photosynthesis such as the large subunit of RuBisCO, RuBisCO activase and the photosystem I reaction centre, which were at higher abundances in potato leaves grown under mineral fertiliser regimes. Proteins known to be induced in response to stress, such as dehydroascorbate reductase and Glutathione S-transferases, were also shown to be up-regulated under mineral fertilisation, possibly associated with higher Cd composition, whereas two proteins known to be involved in biotic stress (1,3-β-d-glucan glucanohydrolase; putative Kunitz-type tuber invertase inhibitor) were more abundant under compost fertilisation. Results showed that switching from mineral to organic fertilisers led to reduced N availability, a significant change in leaf protein expression and lower tuber yield. In contrast, omission of chemosynthetic crop protection inputs had limited effects on protein expression and no significant effect on tuber yield. This study provides information on the effects of changes in nutrient supply on protein expression patterns. It is a prerequisite for the development of functional molecular markers for a directed strategy to inform breeding programmes to improve potato nutrient use efficiency.
Quantitative proteomics to study the response of wheat to contrasting fertilisation regimes
Molecular Breeding, 2013
ABSTRACT Negative environmental impacts from mineral fertilisers and pesticides used in conventio... more ABSTRACT Negative environmental impacts from mineral fertilisers and pesticides used in conventional cropping have raised concern over the sustainability of arable crop production. Organic cropping uses alternatives that avoid many of these negative environmental effects; however, crop yields can be significantly reduced, possibly due to a lower proportion of plant-available nutrients. To gain insights into the molecular effects of organic compared to conventional cropping systems on plant utilisation of nutrients, we used proteomics to analyse winter wheat (Triticum aestivum). Our aim was to investigate the effects of contrasting fertility management and crop protection regimes in organic and conventional cropping systems on the wheat flag leaf proteome and the association between the proteome and physiological traits. Wheat flag leaves were flash-frozen, lyophilised and milled prior to protein extraction (TCA/acetone) and analysed using 2D gel electrophoresis and MALDI-TOF MS. The abundance of 111 protein spots varied significantly between fertilisation regimes. Flag leaf N and P composition were significant drivers of differences in protein spot abundance, including major proteins involved in nitrogen remobilisation, photosynthesis, metabolism and stress response. These results indicate that molecular-based mechanisms are involved in the effect of contrasting cropping systems on nutrient utilisation and wheat grain yield. Using a functional genomics approach, we were able to identify proteins that are linked to causal genes, enabling the potential development of functional molecular markers for crop improvement in nutrient use efficiency.
Effect of Organic and Conventional Crop Rotation, Fertilization, and Crop Protection Practices on Metal Contents in Wheat (Triticum aestivum)
Journal of Agricultural and Food Chemistry, 2011
The effects of organic versus conventional crop management practices (crop rotation, crop protect... more The effects of organic versus conventional crop management practices (crop rotation, crop protection, and fertility management strategies) on wheat yields and grain metal (Al, Cd, Cu, Ni, Pb, and Zn) concentrations were investigated in a long-term field trial. The interactions between crop management practices and the season that the crop was grown were investigated using univariate and redundancy analysis approaches. Grain yields were highest where conventional fertility management and crop protection practices were used, but growing wheat after a previous crop of grass/clover was shown to partially compensate for yield reductions due to the use of organic fertility management. All metals except for Pb were significantly affected by crop management practices and the year that the wheat was grown. Grain Cd and Cu levels were higher on average when conventional fertility management practices were used. Al and Cu were higher on average when conventional crop protection practices were used. The results demonstrate that there is potential to manage metal concentrations in the diet by adopting specific crop management practices shown to affect crop uptake of metals.
European Journal of Agronomy, 2013
The performance of winter wheat was evaluated under organic (ORG) and conventional (CON) manageme... more The performance of winter wheat was evaluated under organic (ORG) and conventional (CON) management systems in the Nafferton Factorial Systems Comparison (NFSC) long-term field trial. The present study separates out the crop protection and fertility management components of organic and conventional production systems using two levels each of crop protection (CP) and fertility management (FM). The experimental design provided the four combinations of crop protection and fertility (CON-CP CON-FM, CON-CP ORG-FM, ORG-CP CON-FM and ORG-CP ORG-FM) to evaluate their effects on yield, quality (protein content and hectolitre weight) and disease levels during the period 2004-2008. The conventional management system (CON-CP CON-FM) out-yielded the organic management system (ORG-CP ORG-FM) in all years by an average of 3.1 t ha −1 , i.e. 7.9 t ha −1 vs. 4.8 t ha −1 . Fertility management was the key factor identified limiting both yield and grain protein content in the ORG management system. The CON-FM produced on average a 3% higher protein content than ORG-FM in all years (12.5% vs. 9.7%). However the ORG-CP system produced higher protein levels than CON-CP although it was only in 2008 that this was statistically significant. In contrast to protein content it was ORG-FM which produced a higher hectolitre weight than the CON-FM system (71.6 kg hl −1 vs. 71.0 kg hl −1 ). The clear and significant differences in yield and protein content between the ORG-FM and CON-FM systems suggest a limited supply of available N in the organic fertility management system which is also supported by the significant interaction effect of the preceding crop on protein content. The pRDA showed that although fertilisation had the greatest effect on yield, quality and disease there was also a considerable effect of crop protection and the environment.
The influence of organic and conventional fertilisation and crop protection practices, preceding crop, harvest year and weather conditions on yield and quality of potato (Solanum tuberosum) in a long-term management trial
European Journal of Agronomy, 2013
Community genetic interactions mediate indirect ecological effects between a parasitoid wasp and rhizobacteria
Ecology, 2010
Indirect ecological effects (IEEs) clearly influence species dynamics and abundance, yet relative... more Indirect ecological effects (IEEs) clearly influence species dynamics and abundance, yet relatively little is known about how they influence the evolution of species involved. While genetic variation in the species causing and responding to the IEE has obvious effects, the influence of genetic variation in intermediate species remains unexamined. Given the often counterintuitive responses of populations to IEEs this seems a significant omission. Following a community genetics approach, we used a model tetra-trophic system (parasitoid wasp, aphid, barley, and rhizobacteria) to investigate the effect of genetic interactions within the two linking species (aphids and barley) on the IEE of rhizobacteria on wasps. We show that 12.4% of the variation in wasp size, a proxy for fitness, is explained by higher-order interactions between aphid genotype (A), barley genotype (B), and presence or absence of rhizobacteria (R) (Genotype[B] x Genotype[A] x Environment[R]). Thus, the IEE of rhizobacteria on the parasitoid wasp is influenced by the specific combination of aphid and barley genotypes that mediate the interactions. In some cases changes in the genotypes of the intermediate species completely reverse the effect of rhizobacteria on wasp size. Our work demonstrates that within-species genetic variation is important in shaping IEEs in communities, an essential component of community evolutionary processes.
PLoS ONE, 2014
Omics analysis (transcriptomics, proteomics) quantifies changes in gene/protein expression, provi... more Omics analysis (transcriptomics, proteomics) quantifies changes in gene/protein expression, providing a snapshot of changes in biochemical pathways over time. Although tools such as modelling that are needed to investigate the relationships between genes/proteins already exist, they are rarely utilised. We consider the potential for using Structural Equation Modelling to investigate protein-protein interactions in a proposed Rubisco protein degradation pathway using previously published data from 2D electrophoresis and mass spectrometry proteome analysis. These informed the development of a prior model that hypothesised a pathway of Rubisco Large Subunit and Small Subunit degradation, producing both primary and secondary degradation products. While some of the putative pathways were confirmed by the modelling approach, the model also demonstrated features that had not been originally hypothesised. We used Bayesian analysis based on Markov Chain Monte Carlo simulation to generate output statistics suggesting that the model had replicated the variation in the observed data due to protein-protein interactions. This study represents an early step in the development of approaches that seek to enable the full utilisation of information regarding the dynamics of biochemical pathways contained within proteomics data. As these approaches gain attention, they will guide the design and conduct of experiments that enable 'Omics modelling to become a common place practice within molecular biology.
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Papers by Catherine Tétard-Jones