Abnormal Guard Cell Development in an Olive Necrotic Mutant of Maize

A study of a mutant variety of Zea mays (ON8147) revealed that the mutant plants, in contrast with normal maize plants, do not exhibit a light‐induced increase in the rate of transpiration, and that the ontogeny of the stomatal complex is abnormal. In later stages of differentiation, the guard cells of mutant plants deteriorate, leaving the mature stomata with only the two subsidiary cells. The subsidiary cells in stomata of mutant leaves are similar to those of normal leaves with respect to their capacity to accumulate K + in the dark, but they do not lose K + in the light, as do subsidiary cells of stomata of nonmutant plants. It is suggested that impairment of guard cell function causes death of the mutant plant seedlings primarily by restricting CO 2 entry into the leaf.