Plant nutrient availability is important not only for sustaining biochemical processes but also for establishing plant defense response against the pathogen invasion. Disease resistance and tolerance in plant are genetically controlled (Simoglou and Dordas 2006). The ability of plant to express its genetic potential for disease resistance can be affected by mineral nutrition. (Dutta et al., 2017). Physical resistance is the first line of defense and is governed by the strength and integrity of cell wall. Nutrients are involved in developing strong cell wall and other tissues. Utilisation of nutrients in disease management requires knowledge on nutrient and their association with plant defense mechanisms (Bastakoti 2023). Nitrogen (N), phosphorus (P) and potassium (K) influence plant defense mechanisms by providing essential building blocks for the synthesis of defense compounds, immune signaling and physiological responses like stomatal regulation. Macronutrient like zinc (Zn), copper (Cu) and iron (Fe) are essential building blocks for the synthesis of defense compounds (Dutta et al., 2024).
Copper (Cu): Copper is an essential micronutrient involved in an array of biological processes in plants and plays a role in plant antiviral immunity (Yao et al., 2022). Cu can suppress plant disease via i) direct toxicity against the pathogen ii) enhance host defense response and iii) direct effect on pathogen aggressiveness (Elmer 2025). The active ingredient is the cupric ion (Cu++) which in the presence of rainwater and other environmental factors such as carbon dioxide in the air and dew, acts against oomycetes, fungi and bacteria (La Torre et al., 2018).
Copper serves as cofactor for many enzymes and plays a key role under stress (Chen et al., 2022). Copper ion mediated antimicrobial activity involve inhibition of enzymes that participate in fungal spore germination or can be directly toxic to bacterial growth (Liu et al., 2015). Cu homeostasis is integral to many plant physiological processes, including lignification of plant cell wall (Hunter et al., 2023). Lignin is a principal structural component of the plant cell wall. It provides strength to the cell wall, facilitates water transport and acts as a physical barrier to the pathogen (Vanholme et al., 2019). Liu et al.(2015) report that copper as low as 10nM protect Arabidopsis plant against Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) infection. In Arabidopsis copper treatment induces reactive oxygen species production as well as callose deposition, activates expression of pathogenesis-related genes and mitogen activated protein kinases signaling pathway (Liu et al., 2015). The copper mediated resistance is dependent on calcium ion flux. Moreover, copper induced responses mimic the defense responses triggered by pathogen-associated molecular patterns (PAMPs). Liu et al. (2015) propose that the proper copper ion concentration can act as an elicitor activating PAMP-triggered immunity-like responses in Arabidopsis.
Copper an essential micronutrient of plant is also an important element for a few pesticides in agriculture suppresses Xanthomonas oryzae pv. oryzae (Xoo) (Yuan et al., 2010). The role of Cu as an antifungal agent may act in part by inducing defense-response genes as well as they may inhibit the pathogen (Sudo et al., 2008). Xoo invades rice plant through hydathodes or wounds, multiplies in the intercellular spaces, then enters xylem vessels and spread in the plant through the vessels to cause disease (Nino-Liu et al., 2006). The bacterial pathogen Xoo overcomes rice defenses by regulating plant host copper redistribution (Yuan et al., 2010). Excess Cu induces oxidative stress and disrupts cellular function, whereas Cu deficiency causes chlorosis, reduced growth rate, delayed flowering and reduced grain setting (Tang et al., 2025). Accumulation of copper is hazardous to micro and macroorganisms. Microorganisms are more sensitive to copper as compared to other organisms in soil (LaTorre et al., 2018). The copper ion dissolved in water on the plant surface can enter the cell protoplasm of the oomycetes, fungi and bacteria (La Torre et al., 2018). Once inside the cells, copper ions interfere with numerous enzymatic reactions and consequently inhibiting spore germination (La Torre et al., 2018). Copper as a protectant means that copper ion should be present on the plant surface before disease occur.
Zinc (Zn): Zinc is an essential micronutrient and has a role in growth, development and defense. Zinc has a role in the functioning of enzymes/proteins like alcohol dehydrogenase, superoxide dismutases, metallothionein and zinc finger protein involved in plant defense response against pathogens (Bastakoti 2023). Zn enhances the signaling of various defense pathways such as salicylic acid-dependent pathways and jasmonic acid/ethylene-dependent pathway as well as improves membrane integrity that assist in protection against invading pathogens (Bastakoti 2023). Zn deficient plant becomes susceptible to infection due to deprived condition whereas an excess level of Zn negatively impacts growth and defense due to toxicity. Zinc can improve structural integrity and permeability of cell membranes which is a defense mechanism against the fungal infection (Machado et al., 2018). Foliar application of Zn significantly reduced the disease severity of tan spot disease of wheat caused by Pyrenophora tritici-repentis (anamorph: Drechslera tritici-repentis) (Simoglou and Dordas 2006). Application of Zn had beneficial effect on tolerance of wheat to Fusarium solani root rot (Khoshgoftarmanesh et al., 2010). Zn fertilization increase tolerance of Medicago truncatula to root-rotting pathogen Rhizoctonia solani (Streeter et al., 2001). Zn-compound has antifungal and antimycotoxin properties. They may inhibit the fungal growth and their ability to produce mycotoxins (Savi et al., 2013).
References:
Bastakoti, S. 2023 Role of Zinc in Management of Plant Diseases: A Review. Cogent Food & Agriculture 9(1): Article: 2194483
doi.org/10.1080/23311932.2023.2194483
Chen, G., Li, J., Han, H., Du, R. and Wang, X. 2022 Physiological and Molecular Mechanisms of Plant Responses to Copper Stress. Int. J. Mol. Sci. 23(21): 12950
doi: 10.3390/ijms232112950
Dutta, A., Dracatos, P. M. and Khan, G. A. 2024 Balancing Act: The Dynamic Relationship Between Nutrient Availability and Plant Defense. Plant J. 120(5): 1724 – 1734
doi: 10.1111/tpj.17098
Dutta, S., Ghosh, P. P., Ghorai, A. K., Roy, M. De. and Das, S. 2017 Micronutrient and Plant Disease Suppression. Fertilizers and Environment News 3(2): 04 – 08
Elmer, W. H. 2025 Copper and Plant Disease. In: “Mineral Nutrition and Plant Disease”. Second Edition. Chapter 12:
https://apsjournals.apsnet.org/doi/pdf/10.1094/9780890546796.012?download=true
Hunter, C., Sun, Z., Mansfield, S. D., Shahbaz, M., Pilon, M. and Gleason, S. M. 2023 The Effects of Copper Deficiency on Lignification Xylem Vessel Structure and Hydraulic Traits in Hybrid Poplar. Physiologia Plantarum 175(5): 1-8
doi.org/10.1111/ppl.14006
Khoshgoftarmanesh, A. H., Kabiri, S., Shariatmadari, H., Sharifnabi, B. and Schulin, R. 2010 Zinc Nutrition Effect on the Tolerance of Wheat Genotypes to Fusarium Root-Rot Disease in a Solution Culture Experiment. Soil Science and Plant Nutrition 56(2): 234 – 243
doi.org/10.1111/j.1747-0765.2009.00441.x
La Torre, A., Iovino, V. and Caradonia, F. 2018 Copper in Plant Protection: Current Situation and Prospects. Phytopathologia Mediterranea 57(2): 201 – 236
doi: 10.14601/Phytopathol_Mediterr-23407
Liu, H., Zhang, B., Wu, T., Ding, Y., Ding, X. and Chu, Z. 2015 Copper Ion Elicits Defense Response in Arabidopsis thaliana by Activating Salicylate- and Ethylene-Dependent Signaling Pathways. Molecular Plant 8(10): P1550 – 1553
Machado, P. P., Steiner, F., Zuffo, A. M. and Machado, R. A. 2018 Could the Supply of Boron and Zinc Improve Resistance of Potato to Early Blight? European Potato Journal 61(2): 169 – 182
doi: 10.1007/s11540-018-9365-4
Nino-Liu, D. O., Ronald, P. C. and Bogdanove, A. J. 2006 Xanthomonas oryzae Pathovars: Model Pathogens of a Model Crop. Mol. Plant Pathol. 7(5): 303 – 324
doi: 10.1111/j.1364-3703.2006.00344.x
Savi, G. D., Bortoluzzi, A. J. and Scussei, V. M. 2013 Antifungal Properties of Zinc-Compounds against Toxigenic Fungi and Mycotoxin. Int. J. Food Sci. Technol. 48(9): 1834 – 1840
doi.org/10.1111/ijfs.12158
Simoglou, K. B. and Dordas, C. 2006 Effect of Foliar Applied Boron, Manganese and Zinc on Tan Spot Development in Winter Durum Wheat. Proceedings of the 12th Congress of the Mediterranean Phytopathological Union. 11 – 15 June 2006 At: Rhodes Island, Hellas. Page 378
Streeter, T. C., Rengel, Z., Neate, S. M. and Graham, R. D. 2001 Zinc Fertilization Increases Tolerance to Rhizoctonia solani (AG 8) in Medicago truncatula. Plant and Soil 228: 233 – 242
Sudo, E., Itouga, M., Yoshida-Hatanaka, K., Ono, Y. and Sakakibara, H. 2008 Gene Expression and Sensitivity in Response to Copper Stress in Rice Leaves. J. Exp. Bot. 59(12): 3465 – 3474
doi: 10.1093/jxb/ern196
Tang, H., Tang, Q., Zhang, J., Chen, X., Tong, T., Zheng, Q., Hao, L., Deng, F., Chen, G., Chen, Z-H., Zeng, F., Qin, Y. and Jiang, W. 2025 Molecular Evolution of Cu Transporters and Transcription Factors in Plant Response to Copper Stress. Plants (Basel) 14(17): 2710
doi: 10.3390/plants14172710
Vanholme, R., De Meester, B., Ralph, J. and Boerjan, W. 2019 Lignin Biosynthesis and its Integration into Metabolism. Curr. Opin. Biotechnol. 56: 230 – 239
doi: 10.1016/j.copbio.2019.02.018
Yao, S., Kang, J., Guo, G., Yang, Z., Huang, Y., Lan, Y., Zhou, T., Wang, L., Wei, C., Xu, Z. and Li, Y. 2022 The Key Micronutrient Copper Orchestrates Broad-Spectrum Virus Resistance in Rice. Science Advances 8(26):eabm0660
doi: 10.1126/sciadv.abm0660
Yuan, M., Chu, Z., Li, X., Xu, C. and Wang, S. 2010 The Bacterial Pathogen Xanthomonas oryzae pv. oryzae Overcomes Rice Defenses by Regulating Host Copper Redistribution. Plant Cell 22(9): 3164 – 3176
doi: 10.1105/tpc.110.078022
