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

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.

Calcium Signaling in Plant-Insect Interactions

“…Plants contain unique Ca 2+ -sensing proteins, the calmodulin-like-proteins (CML), which are involved in many stresses and developmental responses [ 72 ]. In soybean, feeding by S. litura , treatment with signaling compounds and wounding induce the differential expression patterns of CMLs, indicating their involvement in Ca 2+ signaling and plant defense during herbivory [ 79 ]. In defense against herbivory, Arabidopsis CML37 positively regulates the plants’ defense against S. littoralis [ 80 ], whereas CML42 shows a downregulating activity and might play a role as a Ca 2+ sensor by displaying diverse functions in responses to both abiotic stress and insect herbivory [ 81 ].…”

Metabolomics‐driven investigation of plant defense response against pest and pathogen attack

“…Induced defence involves alterations not only at the transcriptome and proteome levels but also at the metabolome level. Plants synthesize secondary metabolites, protease inhibitors, volatile organic compounds and other defensive chemical compounds to fortify against invaders (Mello and Silva‐Filho 2002, Schuler 2011, Singh and Singh 2018, Singh et al 2018b, Singh et al, 2018a, Guan et al 2022, Yadav et al 2022). For example, phytoalexins are antimicrobial components induced as a consequence of insect or microbial attack (Hammerschmidt 1999).…”

Genome-wide identification and expression analysis of calmodulin-like proteins in cucumber

“…As a typical Ca 2+ sensor in higher plants, CMLs possess one to six EF-hand motifs without any other functional domain ( McCormack, Tsai & Braam, 2005 ). To date, CML genes have been analyzed in various species; such as, 50 have been identified in Arabidopsis ( McCormack & Braam, 2003 ), 32 in rice ( Boonburapong & Buaboocha, 2007 ), 68 in grape ( Konstantin et al, 2021 ), 79 in Chinese cabbage ( Nie, Zhang & Zhang, 2017 ), 52 in tomato ( Munir et al, 2016a ), 50 in alfalfa ( Sun, Yu & Guo, 2020 ), 21 in ginkgo ( Zhang et al, 2022 ), 82 in chrysanthemum ( Fu et al, 2022 ), 41 in soybean ( Yadav et al, 2022 ), and 58 in apple ( Li et al., 2019a ; Li et al., 2019b ). Although the cucumber genome has been well assembled and annotated ( Cavagnaro et al, 2010 ; Li et al., 2019a ; Li et al., 2019b ; Osipowski et al, 2020 ), the characteristics and functions of CML gene members are still unknown.…”