Journal of Cell Science, Vol 8, 727-733, Copyright © 1971 by Company of Biologists

Submitted on October 9, 1970

Pollen-Wall Proteins: Electron-Microscopic Localization of Acid Phosphatase in the Intine of Crocus Vernus

¹ Institute of Plant Development, Birge Hall, University of Wisconsin, Madison, Wisconsin 53706, U.S.A.; Department of Botany, Australian National University, Box 4, G.P.O., Canberra A.C.T.
² Institute of Plant Development, Birge Hall, University of Wisconsin, Madison, Wisconsin 53706, U.S.A.; Old Post, Hatfield, Herefordshire, England.

Acid phosphatase has been localized in the wall of the pollen grain of Crocus vernus Wulf at the electron-microscope level by a method using 2-naphthyl thiol phosphate as substrate in a simultaneous coupling reaction with fast blue BBN at pH 5.0, the product being given electron opacity by osmication.

Activity was found to be concentrated mainly in the intine, and to be associated with ribbon-like or filamentous inclusions believed to be proteinaceous on the basis of other criteria. Some activity was also detectable in the interstices of the exine. The observations confirm the general interpretation of the distribution of wall-held enzyme based upon light-microscopic cytochemistry, and provide the resolution necessary to establish unambiguously that they are associated with protein layers inserted during intine growth.