Fig. 3: d-Tagatose effects on expression of PR-protein and defense-related genes in cucumber, rice, and Arabidopsis plants.

RT-qPCR analyses of expression of cucumber PR-protein and defense-related genes after cucumber treatment with d-tagatose with or without inoculation with Pseudoperonospora cubensis. Expression is relative to that in mock-treated leaves (mean ± SD of 2 or 3 independent replications; means were compared using a Tukey–Kramer multiple comparison test; different letters indicate a significant difference among means, p < 0.05). Transcript levels were normalized by comparison with actin (AB010922). Abbreviations are POX (peroxidase), LOX (lipoxygenase), Hrf (pore-forming toxin-like protein), 4CL (4-coumarate-CoA ligase) and CCoAMT (caffeoyl-CoA O-methyltransferase), respectively (a). Relative expression of rice PR-protein genes after rice treatment with various sugars against those without sugar treatment was calculated using data from microarray analyses (mean ± SD of three independent replications; means were compared using a Tukey–Kramer multiple comparison test; different letters indicate a significant difference among means, p < 0.05) (b). Color-coded differential gene expression based on RNA-seq analyses of Arabidopsis thaliana ecotype Col-0 with or without d-tagatose treatment and inoculation with Hyaloperonospora arabidopsidis isolate Noco2 (c). Statistical analyses based on q-values of the respective data in panel c are described in Supplementary Fig. 4a.