Nutrient-Responsive Small Signaling Peptides and Their Influence on the Root System Architecture.

Katerina Lay,Hideki Takahashi

doi:10.3390/ijms19123927

Abstract

The root system architecture (RSA) of plants is highly dependent on the surrounding nutrient environment. The uptake of essential nutrients triggers various signaling cascades and fluctuations in plant hormones to elicit physical changes in RSA. These pathways may involve signaling components known as small signaling peptides (SSPs), which have been implicated in a variety of plant developmental processes. This review discusses known nutrient-responsive SSPs with a focus on several subclasses that have been shown to play roles in root development. Most functionally well-characterized cases of SSP-mediated changes in RSA are found in responses to nitrogen (N) and phosphorus (P) availability, but other nutrients have also been known to affect the expression of SSP-encoding genes. These nutrient-responsive SSPs may interact downstream with leucine-rich repeat receptor kinases (LRR-RKs) to modulate hormone signaling and cellular processes impacting plant root development. SSPs responsive to multiple nutrient cues potentially act as mediators of crosstalk between the signaling pathways. Study of SSP pathways is complicated because of functional redundancy within peptide and receptor families and due to their functionality partly associated with post-translational modifications; however, as genomic research and techniques progress, novel SSP-encoding genes have been identified in many plant species. Understanding and characterizing the roles of SSPs influencing the root phenotypes will help elucidate the processes that plants use to optimize nutrient acquisition in the environment.

Highlights

Plants require macronutrients and micronutrients from the soil to grow and develop
While the CLE3 peptide-encoding gene is induced by NO3−-starvation, it is induced by NH4+ supply after N-starvation [26], indicating these peptides may fine tune the response in the root system architecture (RSA) to the type of N source available
These examples indicate that small signaling peptides (SSPs) signaling modules involved in RSA modulation potentially affect the ability of plants to take up essential nutrients, even if the SSP-encoding gene does not exhibit responsiveness to that specific nutrient cue

Summary

Introduction

Plants require macronutrients and micronutrients from the soil to grow and develop. Due to various geological processes and soil chemistry, these nutrients are heterogeneously distributed in patches and gradients [1]. RSA of most plant species is highly plastic depending on the nutrient environment [3]. These changes occur initially on a molecular level as nutrients are taken up by the plant root system, triggering signaling cascades that alter gene expression and hormone levels, which affect cell growth and differentiation of the root meristems [4]. One way in which plants sense changes in nutrient availability in the environment and convey the information to downstream physiological processes is through the expression of nutrient-responsive small signaling peptides (SSPs). Other SSP families may be derived from functional precursors, the recep5to’ rre-igniodnepofenmdReNnAt m, parnimnaerry, struacnhscarsipatsntoifmmiciRroNbAia, lopr esmptaildl eospe[6n,7re].adTihnegsferaLmReRs -(RsOKRsFasr)e[5c]o. Blue: SSPs rreessppoonnssiviveetotoP,Pa,tatthethteratnrsacnrispctriiopntaiol lneavlell.ePvuerlp. lPeu: SrSpPles:nSoSnP‐rsesnpoonn-srievseptoonNsiovrePtbouNt inofrluPenbcuint gintflheuencing the nunutrtireiennttuuppttaakkeeoorrhhoommeoesotasstiass.iGs.reGenre: eLnR:RL‐RRKRs-.RKs

Nitrogen-Responsive SSPs

Phosphorus-Responsive SSPs

SSP-Dependent Changes on RSA Have Impact on Nutrient Homeostasis

Findings

Conclusions