Managing Rhizoctonia Damping-Off of Rocket (Eruca sativa) Seedlings by Drench Application of Bioactive Potato Leaf Phytochemical Extracts.

Catello Pane,Giuseppe Mennella,Michele Caputo,Massimo Zaccardelli,Roberto Lo Scalzo,Gianluca Francese,Gelsomina Manganiello

doi:10.3390/biology9090270

Catello Pane, Giuseppe Mennella + Show 5 more

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https://doi.org/10.3390/biology9090270

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Abstract

Plants produce a huge array of secondary metabolites that play a key role in defense mechanisms against detrimental microorganisms and herbivores, and represent a suitable alternative to synthetic fungicides in sustainable agriculture. In this work, twelve crude hydroethanolic extracts derived from leaves of different potato cultivars were chemically characterized by LC/MS and their antioxidant properties were investigated in vitro. Furthermore, the biological activity against the fungal pathogen Rhizoctonia solani was evaluated both in vitro and in vivo. Extracts showed the ability to inhibit R. solani growth in vitro and significantly reduced damping-off incidence in in vivo experiments. Furthermore, R. solani mycelia exposed to the extracts showed an altered morphology (low translucency, irregular silhouette, and cytoplasmatic content coagulation) compared to the untreated control in light microscopy examination. Principal component analysis conducted on identified chemical compounds highlighted significant metabolic variations across the different extracts. In particular, those that inhibited most of the growth of the pathogen were found to be enriched in α-chaconine or α-solanine content, indicating that their biological activity is affected by the abundance of these metabolites. These results clearly indicated that plant-derived compounds represent a suitable alternative to chemicals and could lead to the development of new formulates for sustainable control of plant diseases.

Highlights

Damping-off caused by several soil-borne pathogens, including the fungus Rhizoctonia solani Kühn [teleomorph, Thanatephorus cucumeris (Frank) Donk], is a major constraint in many sown vegetable crops
The drawbacks related to the use of chemical fungicides, such as undesirable non-target effects, fungal resistance, and other sustainability reasons are inciting the progressive reduction of many chemical soil disinfectants and fungicides from disease management protocols [4]
The results revealed that Po, Ri, Piccolo Star (PS), and Ha had the highest content of phenolic compounds among the tested extracts (4.5, 4.39, 3.32 and 3.65 mg GAE mL−1, respectively) and the highest free radical-scavenging activity assessed as ascorbic acid (AsA) abundance (2.37, 2.47, 2.15, 1.94 mg AsA mL−1, respectively) (Figure 5)

Summary

Introduction

Damping-off caused by several soil-borne pathogens, including the fungus Rhizoctonia solani Kühn [teleomorph, Thanatephorus cucumeris (Frank) Donk], is a major constraint in many sown vegetable crops. The introduction of new eco-friendly improved non-synthetic plant protection measures is encouraged. According this perspective, many antifungal phytochemicals isolated from higher plants have developed in the last years [5]. Many antifungal phytochemicals isolated from higher plants have developed in the last years [5] They are harmless and non-toxic compounds such as alkaloids, polyphenols, and saponins with remarked antimicrobial properties that make some plant extracts promising for the treatment of multiple plant diseases including the seedling damping-off [6]

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