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of Phytopathology

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Induction of defense response mediated by inulin from dahlia tubers (Dahlia sp.) in Capsicum annuum

By Julio César López Velázquez, Soledad García Morales, Joaquín Alejandro Qui Zapata*, Zaira Yunuen García Carvajal, Diego Eloyr Navarro López, Rebeca García Varela

* Corresponding Author. Email: - / Institution: Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, AC (CIATEJ)

Accepted: 11/December/2023 – Published: 29/December/2023 – DOI: https://doi.org/10.18781/R.MEX.FIT.2305-2

Abstract Background/Objective. Phytophthora capsici is the causal agent of chili wilt. Among the strategies for its control is the use of resistance inducers. Fructans are molecules with interesting biological properties, including the ability to induce resistance mechanisms in some plants. In this work, the protective effect of four concentrations inulin from dahlia tubers on chili infected with P. capsici was evaluated.

Materials and Methods. The concentration that showed the highest protection was chosen to evaluate the induction of defense response through the enzymatic activity of β-1,3 glucanases, peroxidases and the production of total phenolic compounds.

Results. Inulin showed a protective effect against infection at concentrations of 100 to 300 μM, as symptoms decreased and seedlings showed improved vegetative development. It was observed that inulin at 200 μM concentration was able to induce an effective defense response associated with increased activity of β-1,3 glucanases and peroxidases through a local and systemic response in seedlings. This response was differentiated between seedlings treated with inulin and seedlings infected with P. capsici.

Conclusion. It was concluded that inulin has the ability to protect chili bell pepper from P. capsici by induction of resistance.

Keywords: elicitors, Phytophthora capsici, fructans, phenolic compounds, PR proteins

Figure 1. Evaluation of dahlia inulin in the protection of <em>P. capsici</em> infection in chili seedlings. a: Biological effectiveness test of dahlia inulin in chili seedlings, bar equivalent to 10 cm; b: Root damage, bar equivalent to 5 cm; c: Presence of the oomycete in chili roots, bar equivalent to 20 μm, arrows indicate oomycete presence. Treatments as follows: C: Control seedlings, treated with only sterile distilled water; P: Seedlings inoculated with <em>P. capsici</em>; I1+P: Seedlings inoculated with <em>P. capsici</em> and treated with 20 μM of inulin; I2+P: Seedlings inoculated with <em>P. capsici</em> and treated with 100 μM of inulin; I3+P: Seedlings inoculated with <em>P. capsici</em> and treated with 200 μM of inulin; I4+P: Seedlings inoculated with <em>P. capsici</em> and treated with 300 μM of inulin
Figure 1. Evaluation of dahlia inulin in the protection of P. capsici infection in chili seedlings. a: Biological effectiveness test of dahlia inulin in chili seedlings, bar equivalent to 10 cm; b: Root damage, bar equivalent to 5 cm; c: Presence of the oomycete in chili roots, bar equivalent to 20 μm, arrows indicate oomycete presence. Treatments as follows: C: Control seedlings, treated with only sterile distilled water; P: Seedlings inoculated with P. capsici; I1+P: Seedlings inoculated with P. capsici and treated with 20 μM of inulin; I2+P: Seedlings inoculated with P. capsici and treated with 100 μM of inulin; I3+P: Seedlings inoculated with P. capsici and treated with 200 μM of inulin; I4+P: Seedlings inoculated with P. capsici and treated with 300 μM of inulin
Figure 2. Evaluation of β-1,3 glucanase activity in roots (a) and leaves (b) of chili seedlings treated with dahlia inulin and inoculated with <em>P. capsici</em>. C: Control seedlings, treated with sterile distilled water; P: Seedlings inoculated with <em>P. capsici</em>; I: Seedlings treated with 200 μM of inulin; IP: Seedlings inoculated with <em>P. capsici</em> and treated with 200 μM of inulin. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control
Figure 2. Evaluation of β-1,3 glucanase activity in roots (a) and leaves (b) of chili seedlings treated with dahlia inulin and inoculated with P. capsici. C: Control seedlings, treated with sterile distilled water; P: Seedlings inoculated with P. capsici; I: Seedlings treated with 200 μM of inulin; IP: Seedlings inoculated with P. capsici and treated with 200 μM of inulin. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control
Figure 3. Evaluation of peroxidase activity in roots (a) and leaves (b) of chili seedlings. The treatments are described in figure 2. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control
Figure 3. Evaluation of peroxidase activity in roots (a) and leaves (b) of chili seedlings. The treatments are described in figure 2. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control
Figure 4. Quantification of total phenolic compounds in roots (a) and leaves (b) of chili seedlings. The treatments are described in Figure 2. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control
Figure 4. Quantification of total phenolic compounds in roots (a) and leaves (b) of chili seedlings. The treatments are described in Figure 2. The vertical lines represent the standard deviation. Asterisks represent significant differences with respect to the control
Table 1. Growth parameters and protection induced by dahlia inulin in chili seedlings.
Table 1. Growth parameters and protection induced by dahlia inulin in chili seedlings.