Beyond the Usual Suspects: Physiological Roles of the Arabidopsis Amidase Signature (AS) Superfamily Members in Plant Growth Processes and Stress Responses.

José Moya-Cuevas,Stephan Pollmann,Marta-Marina Pérez-Alonso,Paloma Ortiz-García

doi:10.3390/biom11081207

Abstract

The diversification of land plants largely relies on their ability to cope with constant environmental fluctuations, which negatively impact their reproductive fitness and trigger adaptive responses to biotic and abiotic stresses. In this limiting landscape, cumulative research attention has centred on deepening the roles of major phytohormones, mostly auxins, together with brassinosteroids, jasmonates, and abscisic acid, despite the signaling networks orchestrating the crosstalk among them are so far only poorly understood. Accordingly, this review focuses on the Arabidopsis Amidase Signature (AS) superfamily members, with the aim of highlighting the hitherto relatively underappreciated functions of AMIDASE1 (AMI1) and FATTY ACID AMIDE HYDROLASE (FAAH), as comparable coordinators of the growth-defense trade-off, by balancing auxin and ABA homeostasis through the conversion of their likely bioactive substrates, indole-3-acetamide and N-acylethanolamine.

Highlights

Beneath the apparent simplicity of the sessile lifestyle of plants, an intricate hormonebased machinery becomes crucial to face an often hostile environment
Infectious pathogens, herbivorous predators, soil salinity, drought, or temperature fluctuations, are among the diverse biotic and abiotic stresses challenging their survival and optimal reproduction [1,2]. The sensing of these stimuli activates the concerted action of diverse interconnected signaling pathways, wherein the combinatorial action of few major phytohormones orchestrate a wide range of specific physiological processes, depending on both the responding tissue and the stimulus itself [3,4,5]
Amidohydrolase that synthesizes indole-3-acetic acid (IAA) from IAM [31]; FATTY ACID AMIDE HYDROLASE (FAAH), an integral membrane protein which hydrolyzes NAEs, thereby terminating their actions [27]; Glu-tRNAGln amidotransferase, an heterotrimeric enzyme required for the formation of appropiately charged glutamine codons during translation [32]; allophanate hydrolase, crucial for urea usage as a nitrogen source by diverse organisms, by means of allophanate to ammonium and carbon dioxide conversion [33]; peptide amidase (PAM), for selective hydrolysis of the C-terminal amide bond of peptides [34]; the bacterial malonamidase E2 (MAE2) catalyzing the hydrolysis of malonamate to malonate and ammonia, by symbiont bacteroids for transport of fixed nitrogen to plant cells [35]

Summary

Introduction

Beneath the apparent simplicity of the sessile lifestyle of plants, an intricate hormonebased machinery becomes crucial to face an often hostile environment. Infectious pathogens, herbivorous predators, soil salinity, drought, or temperature fluctuations, are among the diverse biotic and abiotic stresses challenging their survival and optimal reproduction [1,2]. In this restricting scenario, the sensing of these stimuli activates the concerted action of diverse interconnected signaling pathways, wherein the combinatorial action of few major phytohormones orchestrate a wide range of specific physiological processes, depending on both the responding tissue and the stimulus itself [3,4,5]. Thereby, our review may fuel future synergistic research approaches, integrating the converging roles of their preferred substrates in early plant growth, leading future biotechnological innovations to sustainably increase crop yields and meet the worldwide growing demand

The AS Superfamily

The Arabidopsis AS Superfamily Members

Findings

Concluding Remarks and Future Perspectives