Figure 3.

Genetic Dissection of Nod Factor Signaling.

Mutations in sym8 and sym19 of pea and dmi1 and dmi2 of M. truncatula block Nod factor–induced calcium oscillation as well as mycorrhizal infection, whereas the pea sym10 mutation blocks calcium oscillation only. Therefore, it is likely that SYM10 acts upstream of SYM8 and SYM19 and probably is involved in a specific Nod factor perception mechanism (Wais et al., 2000; Walker et al., 2000). Calcium oscillation is negatively affected by ethylene as well as by DMI3 (Oldroyd et al., 2001a, 2001b).

(*), SYM9 and SYM30 of pea function downstream of calcium oscillation, but it was not investigated whether they have a control function like DMI3 (Walker et al., 2000).