Figure 3.

Early nodulin gene expression is blocked in nsp2 mutants. A, Expression levels of RIP1 were assessed at time points postinoculation with S. meliloti using northern analysis. Wild-type plants show a gradual induction of RIP1 expression that peaks at 24 h postinoculation. nsp2-1 and nsp2-2 show only a slight induction of RIP1 at 48 h postinoculation. pi, Postinoculation. B, Expression of ENOD11 was assessed using a construct that places uidA under the regulation of the ENOD11 promoter. Roots were treated with 1 nm Nod factor for 6 h and then assessed for GUS activity. Both wild type and nsp2-2 show non-symbiotic root cap expression, but only wild type shows the Nod factor-inducible GUS activity in a region behind the root tip.