Systemic Induced Resistance as a Tool for Disease Control

Plants can be induced to develop enhanced resistance to pathogen infection by treatment with a variety of abiotic and biotic inducers. Biotic inducers include infection by necrotizing pathogens and plant-growth-promoting rhizobacteria, and treatment with nonpathogens or cell wall fragments. Abiotic inducers include chemicals which act at various points in the signaling pathways involved in disease resistance, as well as water stress, heat shock, and pH stress. Resistance induced by these agents (resistance elicitors) is broad spectrum and long lasting, but rarely provides complete control of infection, with many resistance elicitors providing between 20 and 85% disease control. There also are many reports of resistance elicitors providing no significant disease control. In the field, expression of induced resistance is likely to be influenced by the environment, genotype, and crop nutrition. Unfortunately, little information is available on the influence of these factors on expression of induced resistance. In order to maximize the efficacy of resistance elicitors, a greater understanding of these interactions is required. It also will be important to determine how induced resistance can best fit into disease control strategies because they are not, and should not be, deployed simply as “safe fungicides”. This, in turn, will require information on the interaction of resistance elicitors with crop management practices such as appropriate-dose fungicide use.

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Austrian pine phenolics are likely contributors to systemic induced resistance against Diplodia pinea

Tree Physiology ◽

10.1093/treephys/tpt063 ◽

2013 ◽

Vol 33 (8) ◽

pp. 845-854 ◽

Cited By ~ 23

Author(s):

P. Sherwood ◽

P. Bonello

Keyword(s):

Induced Resistance ◽

Systemic Induced Resistance ◽

Diplodia Pinea

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History and Perspectives on the Use of Disease Resistance Inducers in Horticultural Crops

HortTechnology ◽

10.21273/horttech.15.3.0518 ◽

2005 ◽

Vol 15 (3) ◽

pp. 518-529 ◽

Cited By ~ 23

Author(s):

Andrea B. da Rocha ◽

Ray Hammerschmidt

Keyword(s):

Disease Resistance ◽

Disease Control ◽

Induced Resistance ◽

Broad Spectrum ◽

Management Practices ◽

Disease Suppression ◽

Postharvest Disease ◽

High Quality ◽

Horticultural Crops ◽

Resistance Inducers

A major challenge facing horticultural crop production is the need to provide field and postharvest disease control measures that help maintain high quality plant products. Producers and consumers also expect high quality produce with minimal or no pesticide residues and competitive prices. The chemical management of disease is further complicated by the development of fungicide resistance in many important pathogens. Because of these concerns, an alternative or complementary approach is the use of disease resistance inducers that activate the natural defenses of the plant. Induced disease resistance in plants has been studied in many different pathosystems for nearly a century. Resistance to plant disease can be induced systemically by prior infection with pathogens, by certain non-pathogenic microbes that colonize the surface of roots and leaves, or by chemicals. The application of resistance inducers should protect plants through the induction of defenses that are effective against a broad spectrum of pathogens. Over the last few years, a number of materials that could potentially be used as inducers of resistance in horticultural crops have been identified. Some of these materials are already commercially available. Although induced resistance is known to provide a broad spectrum of disease suppression, it may not be a complete solution because variation in the efficacy of disease resistance induction has been observed. The variation in the response may be dependent on the plant species and even cultivars, as well as variability in the spectrum of pathogens that resistance can be induced against. Induction of resistance depends on the activation of biochemical processes that are triggered in the plant, and therefore a lag time between treatment and expression of resistance occurs. This lag effect may limit the practical application of disease resistance inducers. Since the efficacy of the inducers also depends on the part of the plant that was treated, the product delivery (i.e., how the inducers would be applied in order to optimize their action) is another factor to be considered. Some studies have shown that there may be side effects on growth or yield characteristics when certain inducers are used. Understanding the biochemical interactions occurring between plants, pathogens and the inducers will provide information that may be useful for the optimization of this new approach on disease control. Approaches to integrate induced resistance with other management practices need to be investigated as a means to aid the development of sustainable disease management programs that are effective as well as economically and environmentally sound.

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