Abstract: Glycine max L. Merr. (soybean) resistance to Heterodera glycines Ichinohe is classified into two cytologically-defined responses, the G. max [Peking]- and G. max[PI 88788]-types. Microarray analyses comparing these cytologically and developmentally distinct resistant reactions reveal differences in gene expression in pericycle and surrounding cells even before infection. Gene pathway analyses compare the two genotypes (1) before, (2) at various times during, (3) constitutively throughout the resistant reaction and (4) at all time points prior to and during the resistant reaction. The amplified levels of transcriptional activity of defense genes may explain the rapid and potent reaction in G. Max[Peking/PI 548402] as compared to G. max[PI 88788].