Screening for costs of disease resistence caused by stomatal dysfunction

Lead Research Organisation: Aberystwyth University
Department Name: IBERS

Abstract

Wheat varieties combining high yield and good resistance against three of the main foliar diseases in the UK (Septoria tritici blotch, yellow rust and brown rust) have proved elusive. There is now significant evidence in the scientific literature that some disease resistance genes, introduced into varieties by conventional plant breeding, impose a yield penalty on the crop. Hence, breeding for disease resistance creates 'yield drag' which slows the rate of yield improvement. This acts as a disincentive for breeders to focus efforts on selection for resistance, so most commercially popular, high yielding wheat varieties are susceptible to foliar diseases. The result of this is that fungicides are routinely used to control important foliar diseases. Dependence on fungicides is associated with high input costs for the grower and strong pressure for the disease-causing pathogens to develop insensitivity to the fungicides used, reducing the number of fungicides that remain effective. The project proposed here will test important disease resistance genes for their effects on attainable yield. This is difficult to achieve in plant breeding programmes currently, because: (i) there are large numbers of genes to test, (ii) without careful experimentation, measurements of the yield loss caused by each gene are hidden by the yield benefit they provide via disease control, and (iii) testing requires production of wheat lines that differ for presence or absence of the resistance gene but are otherwise highly similar. This is important in order to rule out any effects on yield caused by other differences between the resistant and susceptible wheat lines. It would be useful to be able to select resistance genes which provide the benefit of disease control, without an associated yield cost. Recently, evidence has accumulated that the deleterious effects on yield may be caused by disease resistance responses in the cells of the leaf surface disrupting the function of adjacent stomata. Stomata are pores in the leaf surface that normally open during the day (to allow CO2 to enter the leaf for photosynthesis) and close at night (to prevent unnecessary water loss when the leaf is not photosynthesising). As a result of the stomatal dysfunction caused by the resistance response, they may fail to open fully during the day or fail to shut properly at night. The project proposed here will test the idea that measurements of stomatal function can be used to screen resistance genes, to identify those which are, or are not, likely to have deleterious effects on yield. This would allow wheat breeders to focus on introducing genes which are effective against foliar diseases and benign in their effects on the plant.

Technical Summary

Recent evidence published from controlled environment (CE) studies demonstrates that host resistance responses to challenge by avirulent fungal plant pathogens can cause dysfunction of stomata adjacent to attempted infection sites. Subsequent field experiments, using near-isogenic lines (NILs) differing for presence/absence of resistance genes, have shown that the effects seen in the CE studies also occur in the field and suggest that stomatal dysfunction occurs with a wider range of cereal pathosystems and resistance genes than previously studied. The work proposed here will test the hypothesis that the yield 'cost' associated with certain resistance genes is caused by stomatal dysfunction. Plant breeders are supporting the project, as they require techniques to allow them to characterise novel resistance genes/QTL for the likelihood of an associated yield penalty, to inform decisions about introgression into their breeding material. If the hypothesis is supported, then stomatal conductance measurements could act as an indicator for physiological cost. Alternatively, such costs may be found to be associated with certain types of resistance response which can be characterised by microscopy (termed, microphenotyping). The specific objectives of the proposed LINK project are to: 1. Screen key disease resistance genes for yield costs. 2. Characterise disease resistance genes which contrast for presence or absence of yield cost for effects on stomatal function. 3. Relate stomatal dysfunction at a leaf level to impacts on radiation use efficiency at a canopy level and grain yield. 4. Test stomatal conductance as an indicator of yield potential in the light-limited environment of the UK. 5. Test improved porometry methods to increase screening throughput. The objectives will be addressed by a combination of CE experiments, field trials and microphenotyping, on NILs and lines from mapping populations of wheat, which contrast for key resistance genes.

Planned Impact

Improving crop yield for a given level of crop inputs (principally: land, fertiliser, water and fossil fuel) benefits productivity and reduces environmental impact per tonne of grain. If 'defeated' major genes are found to carry a yield penalty, then selecting against them in plant breeding programmes will increase the rate of yield improvement, without affecting disease control. If currently important resistance genes/QTL are found to carry a yield cost then decisions will need to be made about the trade-off between yield and disease resistance (and hence the degree of dependence on fungicides), until they can be replaced by alternative sources of resistance with lower yield costs. The work will ultimately lead to wheat varieties which combine high yield and good disease resistance. Disease resistance is likely to be more important in future if the availability of effective fungicides is constrained by: (i) revised legislation regulating the approval and use of crop protection products, and (ii) evolution of insensitivity in pathogen populations to the remaining available modes of action. Improving the disease resistance of varieties offers the best prospect for reducing dependence on fungicides and minimising the selective pressure placed on pathogen populations for fungicide insensitivity. Therefore resistant varieties benefit growers by maintaining disease control options, as well as reducing the level of inputs required. High yielding varieties will be crucial to ensure grain production meets projected rising demand and to minimise pressure for land use change and maintain food security. Conversion of grassland and semi-natural vegetation into arable production has adverse consequences for biodiversity and for greenhouse gas emissions from carbon sequestered in soil. Thus, high yielding varieties result in benefits for the wider society.

Publications

10 25 50
 
Description Resistance to plant pathogens in crops is often based on a few genes - often only one - which triggers a local defence response on infection. Before this project started IBERS discovered that this form of resistance result in the immobilisation of leaf pores known as stomata so that they could now longer close in response to drought. This made plant very susceptible to drought and thus may be a "cost" of resistance in field. During this project we have described stomatal immobilisation (which we refer to a "locking") in wheat varieties with a range of "resistance genes" in response to the pathogens; brown and yellow rust. We have also shown that stomatal locking is likely to one feature arising from a whole-scale change in plant biochemistry that comes about through the deployment of the defence response. Therefore, the "cost of resistance" is likely to reflect the outcome of changes in nutrient content of leaves which will influence grain development.
Exploitation Route We are actively interacting with plant breeders who are seeking to identify resistance genes that will have a lesser cost of resistance. We are seeking for further funding to develop our understanding of the genetic basis of this cost to better inform breeding programmes.

New colloborations are expanding this project in Brazil (on wheat) and China (a range of crops, focusing on nitrogen effects) focusing on metabolomics
Sectors Agriculture, Food and Drink

URL http://www.aber.ac.uk/en/ibers/staff/lum/food-security/plant-microbe-interactions/
 
Description (SUPERTEFF) - A new paradigm in boosting orphan crops to super grains: Linking metabolomics and gene editing to improve Teff for global food security and sustainable agriculture
Amount € 224,933 (EUR)
Funding ID 842118 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 03/2020 
End 03/2022
 
Description Access To Masters
Amount € 20,000 (EUR)
Organisation European Commission 
Department European Social Fund
Sector Public
Country European Union (EU)
Start 09/2013 
End 09/2015
 
Description Cost of resistance in Spanish oats 
Organisation Spanish National Research Council (CSIC)
Country Spain 
Sector Public 
PI Contribution We have hosted PhD students which have examined stomatal locking in a range of oat varieties from their breeding programme.
Collaborator Contribution Helping to generate data for the photosynthetic performance of wheat when stomatal are immobilised following pathogen attack.
Impact A number of papers have been published 1. Montilla-Bascon G, Rubiales D, Hebelstrup KH, Mandon J, Harren FJM, Cristescu SM, Mur LAJ, Prats E. Reduced nitric oxide levels during drought stress promote drought tolerance in barley and is associated with elevated polyamine biosynthesis. Sci Rep 2017;7(1):13311. 2. Sanchez-Martin J, Montilla-Bascon G, Mur LA, Rubiales D, Prats E. Compromised photosynthetic electron flow and h2o2 generation correlate with genotype-specific stomatal dysfunctions during resistance against powdery mildew in oats. Front Plant Sci 2016;7:1660. 3. Sanchez-Martin J, Heald J, Kingston-Smith A, Winters A, Rubiales D, Sanz M, Mur LA, Prats E. A metabolomic study in oats (avena sativa) highlights a drought tolerance mechanism based upon salicylate signalling pathways and the modulation of carbon, antioxidant and photo-oxidative metabolism. Plant Cell Environ 2015;38(7):1434-1452. 4. Montilla-Bascon G, Rispail N, Sanchez-Martin J, Rubiales D, Mur LA, Langdon T, Howarth CJ, Prats E. Genome-wide association study for crown rust (puccinia coronata f. Sp. Avenae) and powdery mildew (blumeria graminis f. Sp. Avenae) resistance in an oat (avena sativa) collection of commercial varieties and landraces. Front Plant Sci 2015;6:103. 5. Mur LAJ, Simpson C, Gay A, Smith JA, Paveley N, Sánchez-Martin J, Prats E. Stomatal lock-up following pathogenic challenge: Source or symptom of costs of resistance in crops? Plant Pathology 2013;62:72-82. 6. Mur LA, Prats E, Pierre S, Hall MA, Hebelstrup KH. Integrating nitric oxide into salicylic acid and jasmonic acid/ ethylene plant defense pathways. Front Plant Sci 2013;4:215. 7. Montilla-Bascón G, Sánchez-Martín J, Rispail N, Rubiales D, Mur L, Langdon T, Griffiths I, Howarth C, Prats E. Genetic diversity and population structure among oat cultivars and landraces. Plant Mol Biol Rep 2013;31(6):1305-1314. 8. Sanchez-Martin J, Mur LA, Rubiales D, Prats E. Targeting sources of drought tolerance within an avena spp. Collection through multivariate approaches. Planta 2012;236(5):1529-1545.
Start Year 2011
 
Description Metabolomic assessments of the cost of resistance 
Organisation ADAS
Country United Kingdom 
Sector Private 
PI Contribution Metabolomic and photosynthetic analyses of infected wheat plants to determine the biochemical effects of infection.
Collaborator Contribution Access to field sites and advice on suitable experimental design. Co-analyses of the results
Impact This collaboration contributed to the a major publication output. Mur LAJ, Simpson C, Gay A, Smith JA, Paveley N, Sánchez-Martin J, Prats E. 2013. Stomatal lock-up following pathogenic challenge: source or symptom of costs of resistance in crops? Plant Pathology 62: 72-82.
Start Year 2013
 
Description The Impact of costs of resistance on nutrient use efficiency (NUE) in plants 
Organisation National Institute of Plant Genome Research
Country India 
Sector Charity/Non Profit 
PI Contribution Metabolomic assessments of changes in primary and secondary metabolism in response to infection....with a particular focus in nitrogen metabolism and nitric oxide signalling
Collaborator Contribution Access to rice germplasm with differential responses to infection and NUE.
Impact 1. Mur LAJ, Simpson C, Kumari A, Gupta AK, Gupta KJ. Moving nitrogen to the centre of plant defence against pathogens. Ann Bot 2017;119(5):703-709. 2. Neelwarne B, Gupta KJ, Mur LAJ. Integrating classical and alternative respiratory pathway. John Wiley & Sons;2015. 3. Mur LAJ, Gupta KJ, Hebelstrup K. Ethylene, nitric oxide and haemoglobins in plant tolerance to flooding. Abiotic stresses in crop plants: CABI Publishing;2015. p. 43-53. 4. Gupta KJ, Neelwarne B, Mur LAJ. Integrating classical and alternative respiratory pathways. Alternative respiratory pathways in higher plants: John Wiley & Sons, Ltd;2015. p. 3-19. 5. Gupta KJ, Mur LAJ, Neelwarne B. Alternative respiratory pathways in higher plants. John Wiley & Sons;2015. 6. Shah J, Hebelstrup K, Gupta KJ, Simpson C, Mandon J, Christiansen MW, Mur LAJ, Igamberdiev AU, Cochrane D. Study on biochemical, morphological and physiological effects of nitric oxide turnover in plants under hypoxia.2014. 7. Mur LAJ, Lloyd AJ, Gupta KJ, Charkaborty U, Chakaborty B. Harnessing the power of metabolomics to improve crop tolerance against stress. Annual Review Of Plant Pathology 2014:59. 8. Mur LAJ, Lloyd AJ, Gupta KJ, Chakraborty U, Chakraborty B. Harnessing the power of metabolomics to improve crop tolerance against stress. REVIEW OF PLANT PATHOLOGY 2014;6:59-92. 9. Gupta KJ, Mur LA, Ratcliffe RG. Guarding the guard cells? New Phytol 2014;203(2):349-351. 10. Gupta KJ, Mur LA, Brotman Y. Trichoderma asperelloides suppresses nitric oxide generation elicited by fusarium oxysporum in arabidopsis roots. Mol Plant Microbe Interact 2014;27(4):307-314. 11. Gupta KJ, Brotman Y, Mur LAJ. Localisation and quantification of reactive oxygen species and nitric oxide in arabidopsis roots in response to fungal infection. Molecular Plant Microbe Interactions 2014. 12. Mur LAJ, Hebelstrup KH, Gupta KJ. Striking a balance: Does nitrate uptake and metabolism regulate both no generation and scavenging? Frontiers in plant science 2013;4. 13. Mur LA, Mandon J, Persijn S, Cristescu SM, Moshkov IE, Novikova GV, Hall MA, Harren FJ, Hebelstrup KH, Gupta KJ. Nitric oxide in plants: An assessment of the current state of knowledge. AoB Plants 2013;5:pls052. 14. Mur LA, Hebelstrup KH, Gupta KJ. Striking a balance: Does nitrate uptake and metabolism regulate both no generation and scavenging? Front Plant Sci 2013;4:288. 15. Gupta KJ, Brotman Y, Segu S, Zeier T, Zeier J, Persijn ST, Cristescu SM, Harren FJM, Bauwe H, Fernie AR, et al. The form of nitrogen nutrition affects resistance against pseudomonas syringae pv. Phaseolicola in tobacco. Journal of Experimental Botany 2013;64(2):553-568.
Start Year 2013
 
Description The cost of resistance to tan spot in wheat 
Organisation Embrapa Trigo
Country Brazil 
Sector Private 
PI Contribution we have an collaboration agreement which is aiming to develop wheat lines which are resistant to tan spot. Initially, this is based on a PhD studentship
Collaborator Contribution They have provided germplasm, Tan spot strains and a contribution to the costs of RNA-seq experiments (£3000)
Impact Too early as yet.
Start Year 2018
 
Description UK- China Phenomics- Metabolomics Network 
Organisation Huazhong Agricultural University
Country China 
Sector Academic/University 
PI Contribution We have established wide ranging collaborations focusing on plant phenomics, plant metabolomics and the role of nitrogen in plant stress responses
Collaborator Contribution We are designing new research programmes together and joint publications. The Chinese collaborators cover all of my internal travel and subsistence costs when in China.
Impact This is a multi-disciplinary collaboration involving computer imaging and omic (particularly metabolomic analyses) 1. Sun Y, Wang M, Mur LAJ, Shen Q, Guo S. Unravelling the Roles of Nitrogen Nutrition in Plant Disease Defences. Int J Mol Sci. 2020;21(2). 2. Sun Y, Hou M, Mur LAJ, Yang Y, Zhang T, Xu X, et al. Nitrogen drives plant growth to the detriment of leaf sugar and steviol glycosides metabolisms in Stevia (Stevia rebaudiana Bertoni). Plant Physiol Biochem. 2019;141:240-9. 3. Sun Y, Li Y, Wang M, Wang C, Ling N, Mur LAJ, et al. Redox imbalance contributed differently to membrane damage of cucumber leaves under water stress and Fusarium infection. Plant science. 2018;274:171-80.
Start Year 2018
 
Description UK- China Phenomics- Metabolomics Network 
Organisation Nanjing Agricultural University
Country China 
Sector Academic/University 
PI Contribution We have established wide ranging collaborations focusing on plant phenomics, plant metabolomics and the role of nitrogen in plant stress responses
Collaborator Contribution We are designing new research programmes together and joint publications. The Chinese collaborators cover all of my internal travel and subsistence costs when in China.
Impact This is a multi-disciplinary collaboration involving computer imaging and omic (particularly metabolomic analyses) 1. Sun Y, Wang M, Mur LAJ, Shen Q, Guo S. Unravelling the Roles of Nitrogen Nutrition in Plant Disease Defences. Int J Mol Sci. 2020;21(2). 2. Sun Y, Hou M, Mur LAJ, Yang Y, Zhang T, Xu X, et al. Nitrogen drives plant growth to the detriment of leaf sugar and steviol glycosides metabolisms in Stevia (Stevia rebaudiana Bertoni). Plant Physiol Biochem. 2019;141:240-9. 3. Sun Y, Li Y, Wang M, Wang C, Ling N, Mur LAJ, et al. Redox imbalance contributed differently to membrane damage of cucumber leaves under water stress and Fusarium infection. Plant science. 2018;274:171-80.
Start Year 2018
 
Description UK- China Phenomics- Metabolomics Network 
Organisation Shanxi Agricultural University
Country China 
Sector Academic/University 
PI Contribution We have established wide ranging collaborations focusing on plant phenomics, plant metabolomics and the role of nitrogen in plant stress responses
Collaborator Contribution We are designing new research programmes together and joint publications. The Chinese collaborators cover all of my internal travel and subsistence costs when in China.
Impact This is a multi-disciplinary collaboration involving computer imaging and omic (particularly metabolomic analyses) 1. Sun Y, Wang M, Mur LAJ, Shen Q, Guo S. Unravelling the Roles of Nitrogen Nutrition in Plant Disease Defences. Int J Mol Sci. 2020;21(2). 2. Sun Y, Hou M, Mur LAJ, Yang Y, Zhang T, Xu X, et al. Nitrogen drives plant growth to the detriment of leaf sugar and steviol glycosides metabolisms in Stevia (Stevia rebaudiana Bertoni). Plant Physiol Biochem. 2019;141:240-9. 3. Sun Y, Li Y, Wang M, Wang C, Ling N, Mur LAJ, et al. Redox imbalance contributed differently to membrane damage of cucumber leaves under water stress and Fusarium infection. Plant science. 2018;274:171-80.
Start Year 2018