Figure 4.

Inverse relationship between expression of defense genes and cell cycle genes in root tips treated with SA at a level that inhibits root growth. Relative levels of (A) chitinase mRNA and (B) cyclin mRNA were normalized to actin as a control. Seedlings were grown in cellophane pouches in which SA was added at a concentration that resulted in approximately 50% inhibition of root growth; root lengths were measured nondestructively as by Bauer (1981) before harvesting root tips for RNA-blot analysis, as by Gunawardena and Hawes (2002).