Fig. 7.
Insoluble (A–C) and soluble (D–F) acid invertase activities in maize ovaries on the day of pollination (day 0). (A) Insoluble activity in vivo was localized in upper pedicel tissue. (B, C) Insoluble activity was not detected at low Ψw (B) or in shade (C) but was present if the assay was extended to 24 h. This indicated that insoluble activity was present but very low at low Ψw or in shade. (D) Soluble activity in situ was localized in the nucellus. Although there is some overlap of upper pedicel tissues and nucellus tissue in this section, other sections showed the soluble activity to be restricted to the nucellus (McLaughlin and Boyer, 2004a). (E, F) No activity was detected for soluble invertase at low Ψw (E) or in shade (F). Scale bar = 1 mm. Images are representative of eight control plants, eight plants at low Ψw and three plants in shade.