Antifungal Activity of Ethanolic Extracts from Aeroponically Grown Cape Gooseberry (Physalis peruviana L.) with LED Lights and In Vitro Habituated Roots

Abstract

Green mold caused by Penicillium digitatum is a major post-harvest disease in citrus fruits. Therefore, the search for sustainable and low-environmental-impact alternatives for the management of these fungi is of utmost importance. Physalis peruviana L. is a native fruit of the Peruvian Andes with rich bioactive components present throughout the plant. Its antifungal activity stands out, attributed to its high content of phenols, coupled with its antioxidant capacity and antimicrobial activity. Plants were cultivated aeroponically under a combination of red, mixed (50% red, 50% blue), and green LED lights. Additionally, in vitro-habituated roots free of plant growth regulators were also cultivated. An ethanol extraction assisted by ultrasound for 30 min followed by maceration for 72 h was performed, and the extract was filtrated and evaporated in an extraction hood. Antioxidant activity was assessed using the DPPH method, total polyphenols were measured using the Folin-Ciocâlteu method, and an antifungal test in vitro by the poisoned food method was conducted against P. digitatum. In vitro assays revealed that extracts from leaves, roots, and fruits exerted a significant inhibitory effect on the growth of P. digitatum, as evidenced by a reduction in colony radius when cultured employing the poisoned food method, with IC₅₀ values of 62.17, 53.15, and 286.34 µg·mL^-1, respectively, compared to 2297 µg·mL^-1 for the commercial fungicide Captan 50WP. Although leaves had higher total polyphenol content, no direct correlation with antifungal activity was found. Colored LEDs enhanced phenol accumulation, antioxidant capacity, and antifungal properties in plant parts compared to white LEDs and in vitro roots. These findings suggest P. peruviana as a new alternative biological production system to provide natural compounds for post-harvest disease management.

Keywords: Cape gooseberry; antifungal activity; indoor farming.

Figure 1

Relationship of Trolox equivalent antioxidant capacity (TEAC) of ethanolic extracts of P. peruviana at a concentration of 5 mg·mL⁻¹. Fruit (F), leaf in white LED light (LW), leaf mixed LED light (LM), in vitro-habituated root (RIV), root white LED light (RW), root mixed light (RM). Statistically significant differences are indicated by different letters LSD, (p ≤ 0.05). The error bars in the figure represent the standard error of the mean.

Figure 2

Total polyphenol content (TPC) in extracts of P. peruviana. Extracts of in vitro-habituated root (RIV), Leaf in white light (LW), Root in white light (RM), Leaf in mixed light (LM), Root in mixed light (RM), Fruit (F). Significant differences are denoted by different letters. LSD (p ≤ 0.05).

Figure 3

Growth radius in millimeters (mm) of P. digitatum in medium poisoned by extracts of P. peruviana. Control (C−), control with dimethyl sulfoxide (C+ DMSO), in vitro-habituated root (RIV), leaf in white light (LW), root in white light (RW), leaf in mixed light (LM), root in mixed light (RM), fruit (F), Captan 50 WP (C50). The error bars in the figure represent the standard error of the mean. Statistically significant differences are marked by different letters, based on LSD (p ≤ 0.05).

Figure 4

Percentage of growth inhibition of P. digitatum using ethanolic extracts of in vitro-habituated root (RIV), leaf in white light (LW), root in white light (RW), leaf in mixed light (LM), root in mixed light (RM), fruit (F), Captan 50 WP (C50). The error bars in the figure represent the standard error of the mean.

Figure 5

Antifungal activity results in 7 days post-inoculation of P. peruviana extracts in P. digitatum: Control absolute (C−), control with dimethyl sulfoxide (C + DMSO), positive control with fungicide Captan 50 (C50), fruit (F), leaf white light (LW), leaf mixed light (LM), root in white light (RW), Leaf in mixed light (LM), root in mixed light (RM), in vitro-habituated root (RIV).

Figure 6

P. peruviana cultivated aeroponically: (A) cultivated with white LED light and (B) with mixed LED light.

Figure 7

Habituated in vitro root culture of P. peruviana. (A) Germination and growth in vitro in solid medium. (B) Root growth in solid medium. (C) Transfer of roots to liquid medium. (D) Habituated roots in vitro at 45 days.