Book of Abstracts (PDF) - International Mycological Association

IMC7 Main Congress Theme II: SYSTEMATICS, PHYLOGENY AND EVOLUTION Posters
713 - A comparison of Metarhizium isolates from
natural forest with those from agricultural ecosystems:
A preliminary study
1* 1 1
T.F.N. Kwong , R.Y.C. Kong , L.L.P.
Vrijmoed , E.B.G.
2 2
Jones & N. L. Hywel-Jones
1 Department of Biology and Chemistry, City University of
Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
S.A.R., China. - 2 BIOTEC-Mycology, National Center for
Genetic Engineering and Biotechnology, National Science
and Technology Development Agency, 113 Pahonyothin
RD., Khlong 1, Khlong Luang, Pathum Thani 12120,
Thailand. - E-mail: 97472973@student.cityu.edu.hk
Metarhizium is one of the most studied of insect fungi.
However, most isolates are derived from agro-ecosystems.
We posit that the rate and pattern of evolution of
Metarhizium spp. from natural forest may prove different
from those of agricultural origin. To test this hypothesis a
molecular approach was adopted using selected strains
from the natural forests in Thailand compared with
sequences of key isolates from agricultural strains
downloaded from the Genbank. A region ITS-5.8S rDNA
was sequenced for isolates of Metarhizium from forests in
Thailand. With the inclusion of strains from nature, the
sequence data further confirms the distinct separation of
the Metarhizium isolates into two clades which are well
supported by high bootstrap values: the M. anisopliae and
M. flavoviride clades. The anisopliae clade formed a sister
group to a species from forest off Coleoptera which is
provisionally identified as a Metarhizium anamorph of
Cordyceps taii. No Cordyceps state has been linked with
the flavoviride clade. Long considered an Homopteran
clade, it was notable that two isolates from nature, but off
cockroaches, grouped within flavoviride sensu lato.
Significantly, forest flavoviride from Homoptera (including
leafhoppers and adult cicadas) formed the base of this
clade. Current evidence presented here suggests the
flavoviride clade has host-fidelity while the anisopliae
clade demonstrates host-promiscuity.
714 - The plant tree, roots and clades: mycorrhizae and
plant phylogeny
F.C. Landis, A. Gargas * & T.J. Givnish
University of Wisconsin, Madison, 132 Birge Hall, 430
Lincoln Dr, Madison, WI 53706, U.S.A. - E-mail:
agargas@facstaff.wisc.edu
Most plants obtain at least some nutrients through hyphae
of mycorrhizal fungi, and these symbioses appear to date
back to the early days of plants' land colonization. Since
then, several mycorrhizal types have evolved, each type
allowing exploitation of different nutrient pools and
habitats, yet limiting the symbionts' ranges to areas of
mutual occurrence. As mycorrhizae play important roles in
community and ecosystem ecology, understanding the
evolution of different mycorrhizal states allows researchers
216
Book of Abstracts
to connect plant evolution, community and ecosystem
ecology. Recent substantial advances in our understanding
of plant phylogeny and mycorrhizae in general prompted a
re-evaluation of previously published reports. We mapped
available mycorrhizal data onto current phylogenetic
models of the plant kingdom. The resulting trees show
some interesting patterns, such as a concentration of
ectomycorrhizae in the Eurosids, and they also reveal
significant gaps in our knowledge. These trees, overlays,
and evolutionary commentary are available on the web
(http://www.wisc.edu/botit/MPP/Index.htm or
http://www.botany.wisc.edu/) to provide a practical tool for
teaching about mycorrhizae to systematists and ecologists
of all levels. These comparative data also provide
suggestions for future research leading to elucidation of the
biological mechanisms underlying evolution of these
symbioses.
715 - Incipient sympatric speciation of a fungal
endophyte after host shift
A. Leuchtmann * & D. Brem
Geobotanisches Institut, ETH Zürich, Zollikerstrasse 107,
8008 Zürich, Switzerland. - E-mail:
leuchtmann@geobot.umnw.ethz.ch
Host shifts which promote adaptational changes are
considered to be important in processes of sympatric
speciation. Here, we report on sympatric host races of the
fungal parasite Epichloë bromicola (Ascomycota,
Clavicipitaceae) which presumably emerged after the shift
from the grass Bromus erectus to other Bromus hosts. The
life cycle of E. bromicola infecting B. erectus is
characterized by a conspicuous sexual state (stromata) that
enables the fungus to transmit contagiously, and which
prevents seed production of the host. Asexual strains
infecting the two woodland species, B. benekenii and B.
ramosus, are asymptomatic and transmit vertically by seed.
Analyses of AFLP fingerprinting and of sequences of the
tub2 and tef1 genes of isolates from the three Bromus hosts
collected in Switzerland and nearby France revealed that
isolates are genetically differentiated according to their
host and that the seed-transmitted isolates are derived from
ancestral, sexual strains on B. erectus. These sexual strains
appeared to be compatible with all three hosts, while seedtransmitted
isolates from B. benekenii and B. ramosus were
host specific on these two hosts. However, experimental
matings indicated still unrestricted interfertility among
isolates of all three hosts. We suggest that isolates infecting
B. benekenii and B. ramosus represent long-standing host
races or incipient species, which emerged after host shifts
and which are evolving through host-mediated, disruptive
selection.