Preliminary Study on the Activity of Phycobiliproteins against Botrytis cinerea

Abstract

Phycobiliproteins (PBPs) are proteins of cyanobacteria and some algae such as rhodophytes. They have antimicrobial, antiviral, antitumor, antioxidative, and anti-inflammatory activity at the human level, but there is a lack of knowledge on their antifungal activity against plant pathogens. We studied the activity of PBPs extracted from Arthrospiraplatensis and Hydropuntiacornea against Botrytiscinerea, one of the most important worldwide plant-pathogenic fungi. PBPs were characterized by using FT-IR and FT-Raman in order to investigate their structures. Their spectra differed in the relative composition in the amide bands, which were particularly strong in A. platensis. PBP activity was tested on tomato fruits against gray mold disease, fungal growth, and spore germination at different concentrations (0.3, 0.6, 1.2, 2.4, and 4.8 mg/mL). Both PBPs reduced fruit gray mold disease. A linear dose-response relationship was observed for both PBPs against disease incidence and H. cornea against disease severity. Pathogen mycelial growth and spore germination were reduced significantly by both PBPs. In conclusion, PBPs have the potential for being also considered as natural compounds for the control of fungal plant pathogens in sustainable agriculture.

Keywords: Botrytis cinerea; FT-IR; FT-Raman; cyanobacteria; fungicidal activity; gray mold; phycobiliproteins; plant disease control; plant pathogen; red algae; rhodophyta.

Figure 1

FT-IR spectra of phycobiliproteins (PBPs) from Hydropuntia cornea (left) and Arthrospira platensis (right).

Figure 2

FT-Raman spectra of PBPs from Hydropuntia cornea (left) and Arthrospira platensis (right).

Figure 3

Area percentage of more significant peaks of PBPs from Hydropuntia cornea and (left) and Arthrospira platensis (right) in the region between 1800 and 800 cm⁻¹. The peaks were processed using a Gaussian curve peak fitting. Bars correspond to standard error.

Figure 4

Linear regression of the activity of different doses of PBPs from Hydropuntia cornea (y = 0.523094 + 0.164224x, p < 0.0001) and Arthrospira platensis (y = 0.46725 + 0.169844x, p < 0.0001) against the Botrytis cinerea disease incidence of tomato fruits. Showed data are arcsine transformed. Each value (n = 4) is a mean ± standard error (SE).

Figure 5

Linear regression of the activity of different doses of PBPs from Hydropuntia cornea (y = 60.2313 + 14.7036x, p < 0.0001) against the Botrytis cinerea disease severity on tomato fruits (left) and activity of different doses of PBPs from Arthrospira platensis against disease severity (right). Each value (n = 4) is a mean ± SE. For A. platensis, F_(5,18) = 95.94 (p < 0.05), the asterisk indicates significant difference of treated fruits against untreated according to Tuckey’s multiple comparison test (p < 0.05).

Figure 6

Effect of treatment with PBPs from Hydropuntia cornea at different concentrations on gray mold of tomato fruits.

Figure 7

Effect of treatment of Botrytis cinerea colony portions with different concentrations of PBPs from Hydropuntia cornea and Arthrospira platensis on colony growth at 3 days after treatment. Columns are means values (n = 4) ± SE; F_(5,18) = 399.23 (H. cornea), F_(5,18) = 248.77 (A. platensis). Different letters and the asterisk indicate significant differences according to Tuckey’s multiple comparison test (p < 0.05).

Figure 8

Growth of Botrytis cinerea colonies on potato dextrose agar (PDA) amended with different concentrations of PBPs from Hydropuntia cornea and Arthrospira platensis at 3 days after inoculation. Columns are means values (n = 4) ± SE; F_(5,18) = 29.58 (H. cornea), F_(5,18) = 5.75 (A. platensis). Different letters and the asterisk indicate significant differences according to Tuckey’s multiple comparison test (p < 0.05).

Figure 9

Effect of PBPs from Hydropuntia cornea and Arthrospira platensis on colony forming units (CFUs), and on CFU colony growth of Botrytis cinerea at 2 days after spore treatment. Columns are mean values (n = 4) ± SE. For CFUs, F_(5,18) = 24.84 (H. cornea), F_(5,18) = 9.80 (A. platensis). For CFU colony growth, F_(5,18) = 20.10 (H. cornea), F_(5,18) = 7.63 (A. platensis). Different letters and the asterisk indicate significant differences according to Tuckey’s multiple comparison test (p < 0.05).