The effect of dipicolinic acid on maize tissue culture growth is not solely due to inhibition of lysine biosynthesis.

Dipicolinic acid, a known inhibitor of an enzyme (dihydrodipicolinic acid reductase) in the maize (Zea mays L.) lysine biosynthetic pathway, inhibits the growth of maize suspension and callus cultures. Inhibited cultures contain somewhat lower free lysine levels, but the inhibition of suspension culture growth was not reversible with simultaneous addition of L-lysine to the culture medium. It is concluded that dipicolinic acid does not act solely as an analog blocking lysine production. Dipicolinic acid thus appears to be unsuitable as a selection for maize tissue culture mutants with lysine overproduction.