Phylogenetic analysis and intron/exon configurations of NBS-encoding genes in cucumbers. A phylogenetic tree of NBS-encoding genes was constructed using MEGA 5.0. Introns and exons are drawn to scale with the full encoding regions of their respective genes. Boxes indicate the exon, and lines indicate the intron. 0 = intron phrase 0; 1 = intron phrase 1; 2 = intron phrase 2.