Calmodulin: Coping with biotic and abiotic stresses in soybean (Glycine max (L.) Merr.)

Calcium is a ubiquitous and versatile secondary messenger that enables plant growth through various processes in response to abiotic and biotic stress factors. Plants are immobile and therefore constantly exposed to various environmental stimuli (drought, waterlogging, etc.) and microorganisms such as bacteria, fungi, and viruses resulting in large crop losses. Calmodulin (CaM) is an evolutionarily conserved calcium-binding protein and sensor that occurs in all eukaryotes and performs various functions under stress. CaM-binding proteins (CBPs) such as transcription factors, enzymes and channels are involved in responses to environmental stress. Plants have evolved a sophisticated innate immune system to fight infections, commonly referred to as pathogen- associated molecular pattern (PAMP)-triggered immunity (PTI) and effector-triggered immunity (ETI). Soybean is an economically important legume crop that is constantly confronted with various pests and pathogens, resulting in significant yield and production losses. The article highlights the functions of calmodulin in soybean during biotic (soybean-microbe pathogenesis) and abiotic (soybean-environment) interactions in the light of currently available knowledge on the subject. It also describes the new paradigms in this field, emphasising the need for further investigation and providing up-to-date information on the most plausible approaches to combat this challenge for commercial use.