Seaweed-Based Products and Mushroom β-Glucan as Tomato Plant Immunological Inducers

Abstract

The effects of the abiotic inducers β-glucan, extracted from Shiitake (Lentinula edodes), BFIICaB^® (Kappaphycus alvarezii) and BKPSGII^® (K. alvarezii X Sargassum sp.) on tomato plants infected with Fusarium oxysporum f. sp. lycopersici (FOL) were evaluated through the activity of enzymes related to the induction of resistance at 5 and 10 days after inoculation (DAI). Tomato plants (21 days old, after germination) were inoculated with the pathogen conidia suspension and sprayed with 0.3% aqueous solutions of the inducers. The activities of the enzymes β-1,3-glucanase, peroxidase and phenylalanine ammonia lyase (PAL) were evaluated in fresh tomato leaves collected at 5 and 10 DAI. In all treatments, peroxidase showed the highest enzymatic activity, followed by β-1,3-glucanase and PAL. Between the seaweeds, the inducers extracted from the red alga Kappaphycus alvarezii (BFIICaB^®) promoted the highest enzymatic activity. The exception was BKPSGII^® (K. alvarezii X Sargassum sp.) where the influence of Sargassum sp. resulted in higher peroxidase activity (4.48 Δab₆₀₀ mg P^-1 min^-1) in the leaves, 10 DAI. Both the red seaweed K. alvarezii and the brown alga Sargassum sp. promoted activities of β-1,3-glucanase, peroxidase and PAL.

Keywords: Fusarium oxysporum; Kappaphycus alvarezii; fungicide; tomato.

Figure 1

Negative control (left plant) and plant treated with the inducer β-glucan (right plant), 5 (a) and 10 (b) days after inoculation (DAI).

Figure 2

β-1,3-glucanase induced activity in tomato plants inoculated with Fusarium oxysporum f. sp. lycopersici (FOL) were evaluated 5 and 10 DAI. Plants were treated with distilled water (negative control), Serenade^® (positive control), β-glucan, Kappaphycus alvarezzi extract (BFIICaB^®) and BKPSGII^®. a, b—Equal letters indicate no significant differences at the p-value < 0.05. The statistical analysis was performed separately for each time interval treatment (average ± SD; n = 3).

Figure 3

Peroxidase induced activity in tomato plants inoculated with FOL were evaluated 5 and 10 DAI. Plants were treated with distilled water (negative control), Serenade^® (positive control), β-glucan, BFIICaB^® and BKPSGII^®. a, b: Equal letters indicate no significant differences at the p-value < 0.05. The statistical analysis was performed separately for each time interval after treatment (average ± SD; n = 3).

Figure 4

Phenylalanine ammonia lyase (PAL) activity in tomato induced by the different treatments were evaluated 5 and 10 DAI with FOL. Plants were treated with distilled water (negative control), Serenade^® (positive control), β-glucan, BFIICaB^® and BKPSGII^®. a, b: Equal letters indicate no significant differences at the p-value < 0.05. The statistical analysis was performed separately for each time interval after treatment (average ± SD; n = 3).