Cytosolic and Nucleosolic Calcium-Regulated Molecular Networks in Response to Long-Term Treatment with Abscisic Acid and Methyl Jasmonate in Arabidopsis thaliana

Calcium acts as a universal secondary messenger that transfers developmental cues and stress signals for gene expression and adaptive growth. A prior study showed that abiotic stresses induce mutually independent cytosolic Ca ([Ca ] ) and nucleosolic Ca ([Ca ] ) increases in root cells. However, gene expression networks deciphering [Ca ] and [Ca ] signalling pathways remain elusive. Here, using transgenic to selectively impair abscisic acid (ABA)- or methyl jasmonate (MeJA)-induced [Ca ] and [Ca ] increases, we identified [Ca ] - and [Ca ] -regulated ABA- or MeJA-responsive genes with a genome oligo-array. Gene co-expression network analysis revealed four Ca signal-decoding genes, , , , , as hub genes co-expressed with Ca -regulated hormone-responsive genes and hormone signalling genes. Luciferase complementation imaging assays showed interactions among CAM1, CIPK8, and GAD1; they also showed interactions with several proteins encoded by Ca -regulated hormone-responsive genes. Furthermore, CAM1 and CIPK8 were required for MeJA-induced stomatal closure; they were associated with ABA-inhibited seed germination. Quantitative reverse transcription polymerase chain reaction analysis showed the unique expression pattern of [Ca ]-regulated hormone-responsive genes in , , and . This comprehensive understanding of distinct Ca and hormonal signalling will allow the application of approaches to uncover novel molecular foundations for responses to developmental and stress signals in plants.