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RESEARCH FOCUS: Plant silicon

Plant productivity is often threatened by biotic and abiotic stresses, ranging from herbivorous pests to environmental extremes such as drought.


There is growing consensus that plant silicon can alleviate many of these stresses by improving plant defences against herbivores (e.g. physical structures) and altering physiological processes in the plant (e.g. water use efficiency).


How does silicon do this and can we exploit it for plant protection?


Answering these questions is central to a new research program at the Hawkesbury Institute for the Environment.

Seven projects commencing in 2017-18 are investigating how plants challenged by environmental change and herbivore attack (above- and belowground) could benefit from plant silicon.


We aim to identify the molecular, physiological and chemical mechanisms underpinning these benefits and develop translational opportunities for plant protection.


The program of research is overseen by Associate Professor Scott Johnson in collaboration with colleagues from HIE, Universities in Australia and overseas and industry partnerships. See the full team and project titles.


Johnson, S.N., Waterman J.M., Wuhrer, R.,  Rowe, R.C., Hall, C.R. & X. Cibils-Stewart. (2021). Siliceous and non-nutritious: nitrogen limitation increases anti-herbivore silicon defences in a model grass. Journal of Ecology, 109, 3767-3778.

Cibils-Stewart, X., Mace, W.J., Popay, A.J., Lattanzi, F.A., Hartley, S.E., Hall, C.R., Powell, J.R. & Johnson, S.N. (2021). Interactions between silicon and alkaloid defences in endophyte‐infected grasses and the consequences for a folivore. Functional Ecology, Online early:

Putra, R., Vandegeer, R.K., Karan, S., Powell, J.R., Hartley, S.E. & Johnson, S.N. (2021). Silicon enrichment alters functional traits in legumes depending on plant genotype and symbiosis with nitrogen-fixing bacteria. Functional Ecology: Online early:

Islam, T., Moore, B.D. & Johnson, S.N. (2021). Silicon suppresses a ubiquitous mite herbivore and promotes natural enemy attraction by altering plant volatile blends. Journal of Pest Science. Online early:

Biru, F.N., Cazzonelli, C.I. Elbaum, R. & Johnson, S. N. (2021). Anti-herbivore silicon defences in a model grass are greatest under Miocene levels of atmospheric CO2. Global Change Biology. 27, 2959-2969.

Johnson, S.N., Hartley, S.E., Ryalls, J.M.W., Frew, A., & Hall, C.R. (2021) Targeted plant defense: silicon conserves hormonal defense signaling impacting chewing but not fluid-feeding herbivores. Ecology, 102, e03250


Vandegeer, R.K., Cibils-Stewart, X. , Wuhrer, R.  Hartley, S.E., Tissue, D.T. & Johnson S.N. (2021) Leaf silicification provides herbivore defence regardless of the extensive impacts of water stress. Functional Ecology. 35, 1200-1211.

Waterman, J.M., Cibils-Stewart, X.  Cazzonelli, C.I. Hartley, S.E. & Johnson, S.N. (2021) Short-term exposure to silicon enhances plant resistance to a global insect pest. Ecology 102:e03438.

Johnson, S.N., Hartley, S.E. & Moore, B.D. (2021). Silicon defence in plants: does herbivore identity matter? Trends in Plant Science, 102, 99-101.

Vandegeer, R.K., Zhao, C., Cibils-Stewart, X., Wuhrer, R., Hall, C.R., Hartley, S.E., Tissue, D.T., & Johnson, S.N. (2020) Silicon deposition on guard cells increases stomatal sensitivity as mediated by K+ efflux and consequently reduces stomatal conductance. Physiologia Plantarum, 171, 358-370.

Biru, F.N., Cazzonelli, C.I., Elbaum, R. & Johnson, S.N. (2020). Contrasting effects of Miocene and Anthropocene levels of atmospheric CO2 on silicon accumulation in a model grass. Biology Letters, 16, 20200608.

Cibils-Stewart, X., Powell, J.R., Popay, A.J., Lattanzi, F.A., Hartley, S.E. & Johnson, S.N. (2020). Reciprocal effects of silicon supply and endophytes on silicon accumulation and Epichloë colonization in grasses. Frontiers in Plant Science, 11, 593198

Johnson, S.N., Rowe, R.C., & Hall, C.R. (2020) Aphid feeding induces phytohormonal cross-talk without affecting silicon defense against subsequent chewing herbivores. Plants, 9, 1009.

Hall, C.R., Mickhael, M., Hartley, S.E. & Johnson, S.N. (2020) Elevated atmospheric CO2 suppresses jasmonate and silicon-based defences without affecting herbivores. Functional Ecology, 34, 993-1002.

Putra, R., Powell, J.R., Hartley, S.E., & Johnson, S.N. (2020) Is it time to include legumes in plant silicon research? Functional Ecology, 34, 1142-1157.

Waterman, J.M., Hall, C.R., Mikhael, M., Cazzonelli, C.I., Hartley, S.E. & Johnson, S.N. (2020). Short-term resistance that persists: Rapidly induced silicon anti-herbivore defence affects carbon-based plant defences Functional Ecology, 35, 82-92.

Hall, C.R., Dagg, V., Waterman, J.M. & Johnson, S.N. (2020) Silicon alters leaf surface morphology and suppresses insect herbivory in a model grass species. Plants, 9, 643.

Rowe, R.C., Trębicki, P., Gherlenda, A. & Johnson, S.N. (2020) Cereal aphid performance and feeding behaviour largely unaffected by silicon enrichment of host plants. Journal of Pest Science, 93, 41-48.

Islam, T., Moore, B.D., & Johnson, S.N. (2020) Novel evidence for systemic induction of silicon defences in cucumber following attack by a global insect herbivore. Ecological Entomology, 45, 1373-1381.

Hall, C.R., Waterman, J.M., Vandegeer, R.K., Hartley, S.E. & Johnson, S.N. (2019) The role of silicon in phytohormonal signalling. Frontiers in Plant Science, 10, 1132.

Johnson, S.N., Reynolds, O.L., Gurr, G.M., Esveld, J.L., Moore, B.D., Tory, G.J. & Gherlenda, A.N. (2019) When resistance is futile, tolerate instead: silicon promotes plant compensatory growth when attacked by above- and belowground herbivores. Biology Letters, 15, 20190361.

Johnson, S.N., Rowe, R.C. & Hall, C.R. (2019) Silicon is an inducible and effective herbivore defence against Helicoverpa punctigera (Lepidoptera: Noctuidae) in soybean. Bulletin of Entomological Research, 110, 417–422.

Johnson, S.N., Ryalls, J.M.W., Barton, C.V.M., Tjoelker, M.G., Wright, I.J. & Moore, B.D. (2019) Climate warming and plant biomechanical defences: silicon addition contributes to herbivore suppression in a pasture grass. Functional Ecology, 33, 587-596.


Ryalls, J.M.W., Moore, B.D., Johnson, S.N., Conner, M. & Hiltpold, I. (2018) Root responses to domestication, precipitation and silicification: weeping meadow grass simplifies and alters toughness. Plant and Soil, 427, 291-304.

Johnson, S.N., Ryalls, J.M.W., Gherlenda, A., Frew, A., & Hartley, S. (2018) Benefits from below: silicon supplementation maintains legume productivity under predicted climate change scenarios. Frontiers in Plant Science, 9, 202.

Johnson, S.N. & Hartley, S.E. (2018) Elevated carbon dioxide and warming impact silicon and phenolic-based defences differently in native and exotic grasses. Global Change Biology, 24, 3886-3896.


Ryalls, J.M.W., Moore, B.D. & Johnson, S.N. (2018) Silicon uptake by a pasture grass experiencing simulated grazing is greatest under elevated precipitation. BMC Ecology, 18, 53.


Frew, A., Powell, J.R., Allsopp, P.G., Sallam, N. & Johnson, S.N. (2017) Arbuscular mycorrhizal fungi promote silicon accumulation in plant roots, reducing the impacts of root herbivory. Plant and Soil, 419, 423-433.


Ryalls, J.M.W., Hartley, S.E., Johnson, S.N. (2017). Impacts of silicon-based grass defences across trophic levels under both current and future atmospheric CO2 scenarios. Biology Letters 13, 20160912.


Frew, A., Powell, J. R., Allsopp, P. G. Nader, S. and Johnson S. N. (2017). Host plant colonisation by arbuscular mycorrhizal fungi stimulates immune function whereas high root silicon concentrations diminish growth in a soil-dwelling herbivore. Soil Biology & Biochemistry. 112, 117-126.

Johnson S.N., Hartley S.E., Ryalls J.M.W., Frew A., DeGabriel J.L., Duncan M., Gherlenda A. (2017) Silicon-induced root nodulation and synthesis of essential amino acids in a legume is associated with higher herbivore abundance. Functional Ecology, 31, 1903-1909.

Frew, A., Allsopp, P.G., Gherlenda, A. & Johnson, S.N. (2016) Increased herbivory under elevated atmospheric carbon dioxide concentrations is reversed by silicon-based plant defences. Journal of Applied Ecology, 54, 1310-1319.

Frew, A., Powell, J.R., Sallam, N., Allsopp, P.G. & Johnson, S.N. (2016) Trade-offs between silicon and phenolic defences may explain enhanced performance of root herbivores on phenolic-rich plants. Journal of Chemical Ecology, 42, 768-771.

Johnson, S.N., Benefer, C.M., Frew, A., Griffiths, B.S., Hartley, S.E., Karley, A.J., Rasmann, S., Schumann, M., Sonnemann, I. & Robert, C.A.M. (2016) New frontiers in belowground ecology for plant protection from root-feeding insects. Applied Soil Ecology, 108, 96-107.


   Research Collaborators

  • Australian Steel Mill Services (Gavin Tory and Ben Muscat)

  • Professor Justin Borevitz, Australian National University

  • Dr Chris Cazzonelli, HIE

  • Dr Adam Frew, Charles Sturt University

  • Professor Sue Hartley, University of York, UK

  • Dr Alison Popay, AgResearch

  • Associate Professor Jeff Powell, HIE

  • Professor David Tissue, HIE

  • Dr Piotr Trebicki, Agriculture Victoria Research

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