1985 - Mycological Society of America

24
L. FREDERICK, IVAN L. ROTlI, and lXETER P E N D ~ ~ .
Howard University, Washington, DC 20059, University of
Georgia, Athens, GA 30605, and U. S. Forest Service,
Mge Tinter and Wildlife Division, Atlanta, GA 30309
The "peridial platelets" of Clast&m
cation.
- a clarifi-
Fuller, N. S., see Freshour, G. 0.. et. al.
J.1:. GEMMA and R.E. KOSKE. Department of Botany,
university of Rhode Island, Kingston, R. I. 02881.
Seasonal Spore Dormancy in Gigaspor5 gigantea.
Structures that have been described as "peridial
platelets" =present the key diagnostic feature typifying
the myxcmycete genus Clastodenra. Tnese discrete
flattened structures that persist in sporangia
of I17embers of the genus have been reported to be of
peridial origin. \Ve have investigated the nature of
these "peridial" platelets with scanning electron
microscopy and have found them to be ontogenetically
related to the capillitial system instead of being
derived from the peridium. Platelets develop from
the dichotcmised ends of capillitial branches that
broaden into oval or elongate, flattened, anastarosed
segrrents. They nray have a m t h to slightly pitted
outer surface and smat veined undersurface. me
platelets are relatively thick and the expanded portion
has a clear uninterrupted continuity with the
narm cvlindric ends of the ca~illitial branches.
During the early stages of sporkgial develomnt the
capillitial system and sporoplasm are enveloped by a
thin &rano& peridium. When the sporangib
matures the peridium disintegrates exposing the
underlying cmillitial platelets and the spore mass.
The only portion of the-peridium that persists in a
nature sporangium is a collar-like mant at the top
of the stalk.
Frederick, L., see Howell-Major, Y., et. al.
Frederick, L., see Wilfred, A., et. al.
- G.D.FRESHOUR, -
W.E.8ARSTUW and M.S.FULLER.
Botany Department, The University of
Georgia, Athens, GA 30602. The
ultrastructure of mitosis in Rhizidiomyces
apophysatus.
Serial sections of the early stages of
germination and of sporogenesi s in R.
a o h satus revealed the following features
(I) the angle between the
centrioles of prophase nuclei is ca. 135'
(2) the nuclear envelope persists and is
fenestrated at the poles (3) the nucleolus
disperses into a pocket to the sides of the
metaphase chromosomes and is not seen at
later stages (4) Golgi membranes and
vesicles are abundant adjacent to the
centrioles and polar fenestrae at prophase
and metaphase (5) during metaphase vesicles
move into the spindle apparatus and are
found on either side of the metaphase
chromosomes. At anaphase these i n t ranucl ear
vesicles move ahead of the advancing
chromosomes (6) perinuclear ER and
microbodies surround the nuclei during
anaphase and telophase (7) during telophase
the daughter nuclei are formed by the
addition of new envelope to existing
membranes (8) the mid-region of the original
nucleus is excluded at telophase. The
morphological events of mitosis in K.
apophysatus supports the taxonomic
separation of the Hyphochytriomycota from
the Oomycota and Chytridiomycota.
Freshour, G. D., see Rarstow, W. E., et. al.
Monthly field collections of Gigaspora gigantea
demonstrated seasonal variation in spore number and
percent spore germination. An increase in spore
number in September was correlated with a reduction
in percent germination that continued over a 2 month,
period. Germination of spores on sand plates increased
from 4.2% in September to 945 in December. This
agrees with previously reported evidence for a spore
dormancy period that was found for other vesicular
arbuscular mycorrhizal (VAM) species grown in pot
culture.
R. V. GESSNER, R. I\'. SCIIUL:, :lnd bl. :A. RObLXYO.
Department of Bio1ogic:ll Sciences, licstcrn I1 1 ino is
University, blacomb, IL blJS5. Popul:~t ion gcnct ic
analysis of blorchel la spp.
Starch gel electrophoresis was utilized to investigate
inheritance patterns and the population
structure of blorcllella spp. from west centrill
I1 1 inois. Twelve enzymes encoded by 16 presumpr ive
loci were analyzed from tissue homogenotes of broth
grown mycelium and field collected ascocarps. Data
were analyzed to determine the extent of intrn- and
inter-specific variation within and among populations.
In order to determine the potential for gene flow
between individuals, single iiscospore cultures from
individual ascocnrps of
-
M.
--
del iciosa were studied
and preliminary data silggcst that the a1 1 eles
segregate in a Hendel inn manner. Elect romorph
differences were greater between M. ~leliciosa and
-!I.
csculenta than among individual isolates of
either species. These data support the division of
these taxa into separate species.
- J. L. GIBSON. Department of Botany, University of
FloZdGainesvil le, FL 32611.
Light and Electron Microscopy of Endogone
pisiformis.
Sporocarpic tissues, including zygosporangia and
zygospores, of Endogone pisiformis were examined
with both light and electron microscopy. The
sporocarps are covered by a peridium of
thick-walled, branched, tapering hyphae that stain
reddish-brown in Melzer's reagent. The
zygosporangia develop from the fusion of paired,
apposed gametangia. A primary zygosporangium is
disrupted by an expanding secondary
zygosporangium, within which the zygospore
develops. Zygosporangial and zygospore walls
contrast in staining properties with both light
and electron microscopy. Gametangial septa are
mult iperforate and glebal hyphae possess
infrequent septa with single, central
perforations. The primary constituents of the
zygospore cytoplasm are two types of lipid globule
that differ in their staining properties.
-- J. L. GIBSON and J. W. Kimbrough. Department of
Botany, University of Florida, Gainesville, FL
32611.
Ultrastructure and development of Glaziella
aurantiaca.
Glaziella aurantiaca is a fungus that has been