Figure 3.

Relative expression of genes involved in the melatonin biosynthesis pathway in Valencia sweet orange. Two-way hierarchical cluster analysis (HCA) and its associated heat map diagram of differential nonstandardized gene expression patterns of the predicted melatonin biosynthetic genes in Valencia sweet orange leaves after infection with Ca. L. asiaticus and/or infestation with D. citri (A) or after melatonin supplementation (B) are shown. Rows represent the genes, whereas columns represent different treatments. Low expression levels are colored light blue and high expression levels are colored dark blue (see the scale at the right bottom corner of the heat map). Treatments and genes in the HCA were organized using Ward’s minimum variance method (Ward, 1963). The full list of expressed genes, names, accession numbers, and primers is available in Supplemental Table S1.