An update on redox signals in plant responses to biotic and abiotic stress crosstalk: insights from cadmium and fungal pathogen interactions.

Complex signalling pathways are involved in plant protection against single and combined stresses. Plants are able to coordinate genome-wide transcriptional reprogramming and display a unique program of transcript responses to a combination of stresses which differ from single stresses. However, a significant overlap between pathways and some defence genes in the form of shared and general stress-responsive genes appears to be commonly involved in responses to multiple biotic and abiotic stresses. Reactive oxygen and nitrogen species (ROS/RNS), as well as redox signals, are key molecules involved at the crossroads of perceptions of different stress factors and regulation of both specific and general plant responses to biotic and abiotic stress. In this review, we focus on crosstalk between plant responses to biotic and abiotic stresses, in addition to possible plant protection against pathogens caused by previous abiotic stress. Bioinformatic analyses of transcriptome data from Cd- and fungal pathogen-treated plants focusing on redox gene ontology (GO) categories were carried out to gain a better understanding of common plant responses to abiotic and biotic stresses. The role of ROS and RNS in the complex network involved in plant responses to changes in their environment is also discussed.