A Comprehensive Analysis of Calmodulin-Like Proteins of Glycine max Indicates Their Role in Calcium Signaling and Plant Defense Against Insect Attack.

Manisha Yadav,Indrakant Kumar Singh,Amrita Chakraborty,Md Imtaiyaz Hassan,Archana Singh,Jyotsna Pandey,Jiban Kumar Kundu,Amit Roy

doi:10.3389/fpls.2022.817950

Abstract

The calcium (Ca2+) signaling is a crucial event during plant-herbivore interaction, which involves a transient change in cytosolic Ca2+ concentration, which is sensed by Ca2+-sensors, and the received message is transduced to downstream target proteins leading to appropriate defense response. Calmodulin-like proteins (CMLs) are calcium-sensing plant-specific proteins. Although CMLs have been identified in a few plants, they remained uncharacterized in leguminous crop plants. Therefore, a wide-range analysis of CMLs of soybean was performed, which identified 41 true CMLs with greater than 50% similarity with Arabidopsis CMLs. The phylogenetic study revealed their evolutionary relatedness with known CMLs. Further, the identification of conserved motifs, gene structure analysis, and identification of cis-acting elements strongly supported their identity as members of this family and their involvement in stress responses. Only a few Glycine max CMLs (GmCMLs) exhibited differential expression in different tissue types, and rest of them had minimal expression. Additionally, differential expression patterns of GmCMLs were observed during Spodoptera litura-feeding, wounding, and signaling compound treatments, indicating their role in plant defense. The three-dimensional structure prediction, identification of interactive domains, and docking with Ca2+ ions of S. litura-inducible GmCMLs, indicated their identity as calcium sensors. This study on the characterization of GmCMLs provided insights into their roles in calcium signaling and plant defense during herbivory.

Highlights

Plants being sessile are constantly attacked by various environmental cues that can cause abiotic or biotic stresses (Stotz et al, 2000)
Sixteen of the Glycine max CMLs (GmCMLs) showed higher sequence similarity (85–70%), whereas 25 GmCMLs showed more than 50% sequence similarity with Calmodulin-like proteins (CMLs) of A. thaliana
This transient change in Ca2+ concentration is identified by Ca2+ sensors, which transduce the information to downstream target proteins leading to appropriate defense response

Summary

Introduction

Plants being sessile are constantly attacked by various environmental cues that can cause abiotic or biotic stresses (Stotz et al, 2000). Plants activate their defense mechanism and produce different defensive compounds like secondary metabolites, volatile organic compounds, protease inhibitors, and other antiherbivore chemicals (Gatehouse, 2002; Halitschke and Baldwin, 2004; Kliebenstein, 2004; Schuler, 2011; Vadassery et al, 2012b; Lortzing and Steppuhn, 2016; Singh et al, 2021a,c). This activation of biosynthesis of defensive compounds is governed by certain early events that facilitate the detection of herbivory and signal transduction. It is mandatory to determine the perception molecules, crucial players of signal transduction, and molecular mechanism behind plant defense against herbivory (Kong et al, 2013; Singh et al, 2016, 2020c; Kumar et al, 2020)

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