Domains of Atpase in Plasma Membranes and Transport Through Infected Plant Cells

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.

Plasma Membrane H+-ATPase Activity in Spores, Germ Tubes, and Haustoria of the Rust FungusUromyces viciae-fabae

“…Previous ultrastructural studies with the lead/phosphate precipitation technique did not detect ATPase activity in the haustorial plasma membrane of Uromyces appendiculatus but in the plasma membrane of Erysiphe pisi haustoria (Spencer-Phillips and Gay, 1981). This cytochemical technique, however, has been critized as being not specific for the H + -ATPase (Katz et al, 1988).…”

“…Active transport of nutrients across the host-haustorial interface has been suggested. This was founded on ultrastructural localization of ATPase activity in the fungal plasma membrane (Spencer-Phillips and Gay, 1981;Woods and Gay, 1987). The plasma membrane H + -ATPase of fungi and plants generates the electrochemical proton gradient which is essential for active transport of solutes into cells.…”

High Level Activation of Vitamin B1 Biosynthesis Genes in Haustoria of the Rust Fungus Uromyces fabae

“…Low apoplastic concentrations could be one explanation for the evolution of haustoria if they form an interface at which increased metabolite efflux from the host cell occurs, due to an increase in cytoplasmic solute concentration or plasma membrane permeability (Patrick 1989). Evidence for the latter has been obtained by cytochemical studies that indicate that the host-derived extrahaustorial membrane might be depolarized due to the lack of plasma membrane ATPase activity (Spencer-Phillips and Gay 1981;Baka et al 1995).…”

DYNAMIC EXPERIMENTAL EVIDENCE FOR THE PLASMA MEMBRANE ATPase DOMAIN HYPOTHESIS OF HAUSTORIAL TRANSPORT AND FOR IONIC COUPLING OF THE HAUSTORIUM OF ERYSIPHE GRAMINIS TO THE HOST CELL (HORDEUM VULGARE)

“…The hypothesis was founded on cytochemical investigations of plants infected by powdery mildew and rust fungi (Spencer-Phillips & Gay, 1981). It was found that the region of the host plasma membrane invaginated around each haustorium did not exhibit the ATPase activity characteristic of the rest of the plasma membrane, which was indistinguishable from that in uninfected tissues.…”

“…Thus, although the host cells are not killed, they sustain abnormal losses. An hypothesis for its operation in infections by fungal haustoria was first proposed by Spencer-Phillips & Gay (1981) and has subsequently been applied to a wide range of species of pathogens and plants. However, it has not been confirmed by dynamic experiments and the present paper seeks to remedy the deficiency.…”