Figure 6

Hierarchical clustering and heat map of nectary-specific genes in N. attenuata . To identify nectary-specific genes in N. attenuata, a 44 K Agilent microarray designed for N. attenuata was used (GEO accession number GPL13527). Raw intensities were normalized using the 75th percentile value, and log₂ transformation prior clustering analysis. After K-mean clustering, we selected a total of 3658 probe sets that expressed higher in nectary than in each other tissues; leaf, root, stem, and corolla. The R hclust function was used to generate the heat map and to carry out the hierarchical clustering based on the Euclidean distance. The accumulation levels of transcripts are color-coded: red, high expression; yellow, middle expression; white, low expression. All microarray data with each probe name were deposited in the NCBI GEO database (accession number GSE30287, GSE30124, GSE43394).