Submitted to: Plant Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/12/2014
Publication Date: 5/27/2014
Citation: Goyal, R.K., Mattoo, A.K. 2014. Multitasking antimicrobial peptides, plant development, and host defense against biotic/abiotic stress. Plant Science. DOI:10.1016/j.plantsci.2014.05.012. Interpretive Summary: Enhanced crop protection against extreme environments and pathogens is directly linked to global food security. Apart from known defense mechanisms that plants use against pathogens, a more recent development has been the identification and characterization of very small-size proteins called antimicrobial peptides (AMPs). AMPs are ubiquitous in nature. Their potential as defense molecules in plant disease has been revealed by studies on transgenic plants that were engineered to express various AMPs in different crops. Unlike other disease resistance mechanisms, AMP-dependent resistance may have little or no fitness cost. Their low-cost and high resistance performance is a plus point for generating sustained and strong defense against biotic and abiotic stress by developing novel AMP-plants. Our studies have presented compelling experimental evidence showing that an engineered AMP, called msrA3, has a moonlighting function in potato growth and development while providing resistance against pathogens. A deeper analysis of crop plants engineered with AMPs should provide a key to understanding some of the intricacy and sophistication of plant developmental biology in relation to abiotic and biotic stressors. This manuscript reviews these data in light of the now vast literature on AMPs. It will be of use to biologists, pathologists, and agriculturists interested in developing new crops with durable resistance to disease as well as to abiotic stresses.
Technical Abstract: Crop losses due to pathogens are a major threat to global food security. Plants employ a multilayer defense system against pathogens including use of physical barriers (cell wall), induction of hypersensitive defense response (HR), resistance (R) proteins, and synthesis of antimicrobial peptides (AMPs). Unlike a complex R gene-mediated immunity, AMPs directly target diverse microbial pathogens. Many times, R-mediated immunity breaks down and plant defense is compromised. Although R-gene dependent pathogen resistance has been well studied, comparatively little is known about the interactions of AMPs with host defense and physiology. AMPs are ubiquitous, low molecular weight peptides that display broad spectrum resistance against bacteria, fungi and viruses. In plants, AMPs are mainly classified into cyclotides, defensins, thionins, lipid transfer proteins, snakins, and hevein-like vicilin-like and knottins. Genetic distance lineages suggest their conservation with minimal effect of speciation events during evolution. AMPs provide durable resistance in plants through a combination of membrane lysis and cellular toxicity of the pathogen. Plant hormones - gibberellins, ethylene, jasmonates, and salicylic acid, are among physiological regulators that regulate the expression of AMPs. Transgenically produced AMP-plants have become a means showing that AMPs are able to mitigate host defense responses while providing durable resistance against pathogens.