BEN # 145
aceska at CUE.BC.CA
Thu Oct 3 10:34:09 EST 1996
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No. 145 October 3, 1996
aceska at freenet.victoria.bc.ca Victoria, B.C.
Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2
DR. TADEUS REICHSTEIN (1897-1996)
From: Mary Gibby <M.Gibby at nhm.ac.uk>
Tadeus Reichstein was born on 20th July 1897 in Wloclawek, at
that time in Russian Poland. The family moved to Switzerland in
1906. During the 1920s he worked on the isolation of the
volatile constituents of the flavour of roasted coffee, and in
the 1930s he developed a method for the commercial synthesis of
Vitamin C. For his work on adrenal cortical hormones he was
awarded the Nobel Prize for Medicine and Physiology in 1950,
together with E.C. Kendall and Philippe Hench. Since being made
Emeritus Professor in 1967 he has worked full-time on ferns. His
interests were wide-ranging and global. He was in correspondence
with pteridologists from many parts of the world. His fascina-
tion was for polyploid fern complexes, but he also has spent
many years working on the pteridophytes for Flora Iranica. He
continued to use his expertise in organic chemistry in the
investigation of phloroglucinols in Dryopteris. In all his fern
work he was a great collaborator, and practically all his fern
papers have been multi-authored. An exception is a favourite
subject, his 1981 paper on "Hybrids in European Aspleniaceae
(Pteridophyta)", Bot. Helv. 91: 89-139.
He died on 1st August 1996 at the age of 99.
MYCORRHIZAL LANDSCAPES (BOTANY BC LECTURE)
From: "Hugues B. Massicotte" <hugues at unbc.edu>
The botanical landscape can be seen as a mycorrhizal landscape,
a landscape where the roots of most plant species form interac-
tive and beneficial partners with a variety of fungal species.
In my talk I explored the astonishing structural complexity and
hinted at the ecological significance of a variety of mycor-
rhizal symbioses found in B.C. and, indeed, worldwide. With the
aid of a variety of microscopy techniques and numerous floristic
examples, I explored and compared the significant features which
make vesicular-arbuscular, ecto-, ectendo-, arbutoid, ericoid,
monotropoid and orchid mycorrhizae.
Fungi involved in mycorrhizal relationships range from being
very specific to their host (usually one plant genus), to being
generalists, associating with an immense array of hosts, perhaps
a clue to their numerous ecological contributions.
For example, several important genera of trees in B.C., such as
Pinus, Picea, Pseudotsuga, but also smaller plants, such as
Dryas and Kobresia, form ectomycorrhizae with their respective
fungal symbionts (mostly basidiomycetes and ascomycetes). These
ectomycorrhizae have a Hartig net (the functional interface
between the fungus and the root cell) where presumably exchanges
of metabolites take place, and a fungal sheath (or mantle) which
surrounds the root and interfaces with the soil matrix,
facilitating the uptake of nutrients and water by the plant.
Worldwide, it is estimated that over 5000 species of ectomycor-
rhizal fungi has been described.
Ectendomycorrhizae, monotropoid and arbutoid mycorrhizae, repre-
sent variations in some aspects of the ectomycorrhizal theme!
Like ectomycorrhizae, ectendomycorrhizae have a Hartig net and a
mantle, but also have intracellular coils, fungal hyphae that
exist inside the root cells. The functional significance of
these coils is unclear (after all, a Hartig net is already
present). However, species, such as the genus Wilcoxina, is a
fungus presumably involved worldwide with pine species. Arbutoid
mycorrhizae are very similar to ectendo structurally, except
that all fungal structures are restricted to the outer layer of
root epidermal cells, as in other ericaceous plants (see below).
The fungi involved with arbutoid plants are the same as those
forming ectomycorrhizae, a phenomenon that could theoretically
open the doors for "linkages" between hosts involved in these 2
classes. Demonstration of these ecological linkages will occupy
the researcher well into the 21st century!
In the case of vesicular-arbuscular (VA) mycorrhizae, found on
hundred of species in B.C., (from herbs to woody perennials,
Liliaceae, Rosaceae, Asteraceae, Juglandaceae to name a few) ,
it is the "haustoria-like" arbuscule (i.e. a tree-like fungal
structure), which develop within root cells, that act as the
functional interface for exchange between the plant and the
fungus. The vesicles (i.e. intracellular flask-like fungal
structures) act as the "warehouses" where the fungus can store
lipids. The fungi involved in VA relationships are not diverse,
perhaps 200 species worldwide, and exhibit low specificity for
their hosts in general...one fungus can interact with most VA
hosts. To date, no one has succeeded in growing these VA fungi
in pure culture, emphasizing the obligate nature of these sym-
The ericoid mycorrhizae involve numerous ericaceous hosts (Gaul-
theria, Rhododendron, Vaccinium, Calluna, etc.) and usually a
"select" group of septate ascomycete fungi. They appear to be
broad host ranging among ericaceous hosts but are restricted to
them. Ericaceous host roots are very minute and the fungus
usually interacts with the root epidermis, forming coils within
each colonized cell. The mutual transfer of metabolites happens
The most curious mycorrhizae, which has intrigued plant
physiologists for decades, involve monotropoid hosts (Monotropa,
Pterospora, etc.) and possibly a subset of the vast ectomycor-
rhizal fungi pool. These plants are heterotrophic, obtaining
carbohydrates from other sources, therefore it is hard to under-
stand how fungi benefit by forming mycorrhiza with these plants.
It seems the fungi are involved in a tripartite "contract", in
which they first derive carbohydrates from a true autotrophic
host (typically Picea, Pinus, etc.) and then transfer some to
the monotropoid plant, apparently an "altruistic" transfer?!. It
is unclear what the fungus gets in return but speculation
The last intriguing class, the orchid mycorrhizae, are even
lesser known. With a worldwide diversity of orchid species
exceeding the 20 thousands, and with a select group of
basidiomycetes interacting with orchid tissues, either at the
time of seed germination or at the time of symbiotic root forma-
tion, we find ourselves in the infancy of orchid mycorrhizae
research! Here too, fungal coils invading cells are the presumed
site of metabolite exchanges.
Our understanding of these complex mutualistic associations is
still limited when one considers the vast undescribed diversity
of fungi actually inhabiting the soil with their plant hosts!
The living soil is truly one of our last frontiers...
Dr. Hugues B. Massicotte
University of Northern British Columbia
Prince George, B.C.
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