An Antifungal Synthetic Peptide Derived from Osmotin Protein Application No: 202041015632
A plant-derived small peptide that protects black pepper (Piper nigrum) from devastating 'quick wilt' disease
Background of the invention
In black pepper (Piper nigrum), the ‘quick wilt’ disease caused by the oomycete pathogen Phytophthora capsica (Ph.capsici), is a major production constraint reported globally. Phytophthora capsici is an oomycete (fungal-like) pathogen which is one of the most devastating plant pathogens. The key to pathogenic oomycetes' success resides in their capacity to adapt to overcome host resistance and occasionally jump to new hosts. Control of oomycete diseases relies mainly on chemical measures, however, resistance evolved against most of these chemical oomycete inhibitors and the overused chemical oomyceticides have resulted in serious environmental pollution and drug resistance. Hence, eco-friendly bio-oomyceticides are required for sustainable development and my lab focuses on identifying and characterizing plant and pathogen derived molecules that can be used as bio oomyceticides.
Piper colubrinum is the only wild pepper species highly resistant to Ph.capsici. Through earlier studies in my lab, Osmotin, a defense protein from Piper colubrinum was expressed as a recombinant protein in E. coli. The recombinant Osmotin protein exhibited inhibitory activity against Ph.capsici in vitro.
Based on results from in silico docking studies in P. colubrinum osmotin protein, a short cyclic peptide was synthesized. It was observed that the peptide synthesized from Osmotin protein of P. colubrinum shows significant antifungal activity against Ph. capsici. In vivo studies in the susceptible plant (Piper nigrum) indicated that the synthetic osmotin peptide is more potent than the purified whole protein in inhibiting growth of the pathogen (Ph.capsici). The peptide shows inhibitory activity on pathogen hyphae as well as sporangia. Osmotin peptide pretreatment also significantly induces the expression of key genes of secondary metabolite (phenyl propanoid) pathway and Reactive Oxygen Species (ROS) signaling pathways in healthy leaves. Increased ROS production correlates with expression of innate immune responses in the plant including Hypersensitive Response (HR). Osmotin peptide exhibits more pronounced defence priming potential than the known commercially available defense elicitor Glycol Chitosan.
The peptide has potential application in black pepper crop protection, both as an antifungal and as a priming agent. The peptide can be used alone or in combination with other defence elicitor/s and currently used fungicides for more effective biological control of quick wilt. The peptide and peptide containing preparations will have applications in pepper nursery as well as in pepper plantations. The activity of this peptide against other potential oomycete pathogens affecting other crops is yet to be worked out which is a promising area to be looked into. Studies have to be performed to identify the molecular targets and mechanism/s involved in the antifungal activity of the Osmotin peptide.
The utility of using plant derived bioactive antifungal peptides alone or in combination with chemical antifungals will help in reducing the environmental hazards and associated health risks that result from indiscriminate use of chemical fungicides. The present invention provides a greener and environment-friendly option of fungicide.