Speakers

Biography

Dr. Dilip Shah has been a Principal Investigator at the Donald Danforth Plant Science Center in Missouri since 2001. His lab investigates the mechanisms of action and biotechnological applications of naturally occurring antifungal peptides called defensins and defensin-like NCR peptides. These peptides have the potential for development as antifungal agents for the control of fungal diseases in agriculture. Dilip Shah has over 35 years of experience in plant molecular biology and agricultural biotechnology. During his previous tenure at Monsanto Company, he contributed substantially to developing Roundup herbicide-resistant crops. He is a co-inventor on several patents, and his patents on glyphosate-tolerant crops were listed as “Ten Patents That Changed the World” in the 2003 year-end publication of Intellectual Property Worldwide. He won the 2019 Bar Association of Metropolitan St Louis Inventor of the Year Award. He is also a co-founder of the Peptyde Bio Company, which designs and develops antimicrobial peptides for crop protection.

Abstract

Fungal pathogens cause significant losses of crop yield globally. Chemical fungicides have been instrumental in protecting crops from fungal diseases. However, increasing fungal resistance to many of the single-site chemical fungicides calls for the development of safe and sustainable fungicides with novel multi-site modes of action (MoA). The cysteine-rich plant antimicrobial peptides with potent antifungal activity have emerged as promising candidates for developing novel peptide-based fungicides.

Hundreds of nodule-specific cysteine-rich (NCR) peptides are expressed specifically during nodule development and differentiation in nitrogen-fixing legumes such as Medicago truncatula and Cicer arientinum. Several such peptides exhibit potent antimicrobial activity. However, their structure-activity relationships and mechanisms of action against fungal pathogens are still largely unknown. A highly cationic 36-amino-acid NCR044 peptide with two disulfide bonds is expressed in the nodules of M. truncatula. It exhibits potent antifungal activity against Botrytis cinerea and Fusarium graminearum. NCR044 peptide has a unique, highly dynamic three-dimensional structure and exhibits multi-faceted mechanisms of action against B. cinerea. Confocal and super-resolution microscopy shows peptide localization at the cell wall, foci adjacent to the plasma membrane, cytoplasm, and nucleoli of this fungus. A carboxy-terminal 17-amino-acid  sequence motif essential for the antifungal activity of NCR044 has been identified.

NCR13 is a highly cationic 32-amino-acid peptide from Cicer arientium and contains three predicted disulfide bonds. Surprisingly, its expression in Pichia pastoris leads to the production of two disulfide variants that are identical in the amino acid sequence but differ only in the arrangement of disulfide bonds. These two variants have striking differences in their antifungal potency in vitro, stability after internalization into fungal cells, and multi-faceted modes of action.      

Exogenous application of NCR044 confers resistance to a gray mold disease caused by B. cinerea in tobacco and tomato plants and post-harvest products. The exogenous application of the two NCR13 disulfide variants on tomato and pepper plants also confers strong resistance to gray mold. However, these two disulfide variants differ in their potency against this disease.  Our work paves the way for the future development of NCR peptides as spray-on bioinspired fungicides.