DOMAINS OF ATPASE IN PLASMA MEMBRANES AND TRANSPORT THROUGH INFECTED PLANT CELLS

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Abstract
Summary: The sites of ATPase at pH 7·2 and β‐glycerophosphatase at pH 5·5 and 7·2 in the presence of Mg2+ have been determined by a lead precipitation technique and electron microscopy in leaves of Pisum sativum and Phaseolus vulgaris infected, respectively, with Erysiphe pisi and Uromyces appendiculatus.In the two plants, ATPase activity was similarly high in plasma membranes of epidermal, phloem transfer and companion cells and much lower in those of their mesophylls. The domain of the host plasma membrane invaginated around haustoria showed neither of these enzymic activities but infection did not otherwise alter their activities in either the rest of the plasma membranes of infected cells or the plasma membranes in uninfected cells. In Erysiphe pisi, the plasma membrane showed high activities with ATP and β‐glycerophosphate in haustoria but in other regions and in Uromyces appendiculatus, it lacked activity with both substrates. The sites of transition of the enzymic activities in all instances occurred at annular structures previously described in the haustorial necks.A mechanism of solute transport into haustoria is proposed and discussed in the light of the polarized distribution of ATPase activity in infected cells.