Introduction to Fungi, Third Edition

14 INTRODUCTION
Fig1.11 Ion fluxes in a growing hypha.The
proton (H þ ) gradient across the plasma
membrane is generated by subapical
ATP-driven expulsion of protons. It is used
for the active uptake of nutrients by porters.
Channels also exist for most of the nutrients
but are not shown here, except for the K þ
channel which operates to compensate for
charge imbalances. Dotted arrows
indicate movement of a solute against its
concentration gradient; solid arrows
indicate movement from concentrated to
dilute.For details, see Garrill (1995).
1.3 Hyphal aggregates
Whereas plants and animals form genuine
tissues by their ability to perform cell divisions
in all directions, fungi are limited by their
growth as one-dimensional hyphae. None the
less, fungi are capable of producing complex
and characteristic multicellular structures which
resemble the tissues of other eukaryotes. This
must be controlled by the positioning, growth
rate and growth direction of individual hyphal
branches (Moore, 1994). Further, instead of
spacing themselves apart as during invasive
growth, hyphae must be made to aggregate.
Very little is known about the signalling events