Transcriptome Analysis Reveals Calcium-Induced Defense Response in Barley Against Magnaporthe oryzae

In this study, we found that exogenous 50 mM calcium chloride treatment reduced the number of barley leaf lesions per plant by 39%. To investigate the molecular basis for this increased resistance, we used Magnaporthe oryzae spores to infect barley and collected the leaves for analysis. Four groups were set up: control, pathogen inoculation, 50 mM CaCl2 treatment, and 50 mM CaCl2 treatment plus pathogen inoculation for transcriptomics. Our results showed that both calcium treatment and pathogen inoculation altered the expression of many genes, which were enriched in linoleic acid metabolism, cutin, suberine and wax biosynthesis, flavonoid biosynthesis, phenylpropanoid metabolism, and plant–pathogen interaction pathways. Notably, qRT-PCR analysis revealed that the expression levels of disease-resistance-related genes THN3, RGA4, and FAR4 were significantly reduced in the CaCl2-treated and pathogen-inoculated group compared with the control. Our findings demonstrate that exogenous calcium modulates gene expression and regulatory networks associated with barley disease resistance.