Message - 7th IAL Symposium

Lichen: from genome to ecosystem in a changing world
1I-P
(1I-P7) Submission ID: IAL0260-00002
DEVELOPMENT OF COMPLEMENTARY MOLECULAR MARKERS SEEMS CRUCIAL TO
DETECT THE COEXISTENCE OF DIFFERENT TREBOUXIA TAXA
IN A SINGLE LICHEN THALLUS
Català García S. 1 , Del Campo E.M. 2 , Barreno E. 1 , García- Breijo F.J. 3 , Reig- Armiñana J. 1 , Casano L.M. 2
1 Botany, University of Valencia, Inst. Cavanilles of Biodiversity and Evolutionary Biology, Burjassot, Spain
2 Dept. Plant Biology, University of Alcala, Alcala De Henares, Spain
3 Agroforestry Ecosystems Dept, Polytechnic University of Valencia, Valencia, Spain
Most lichens are associated with Trebouxia phycobionts and some of them simultaneously include
genetically different algal lineages. Recently, on the basis of anatomical and molecular analyses, it was demonstrated
that in Ramalina farinacea (L.) Ach. two species of Trebouxia were always coexisting in a single thallus,
even in geographically distant localities. In this work we investigate if Ramalina fraxinea populations may be representative
of an unknown complex model of lichen symbiosis in which more than two different Trebouxia phycobionts
can coexist as primary producers in each individual thallus. To reach this goal we made both molecular
and TEM analyses. Molecular analyses based on three different molecular markers- nrITS, psbA and 23S rDNA-
allowed to detect the co-existence of at least two phycobionts per thallus. One or them could be included within a
Trebouxia decolorans complex whereas the other seemed to be very similar to one of the two coexisting phycobionts
in R. farinacea referred as Trebouxia TR1 (T. jamesii-like) in previous works. Phylogenetic analyses based
on these markers indicated a high and unexpected cryptic speciation within the Trebouxia decolorans complex.
At least, five haplotypes and morphotypes were recognized among T. decolorans-like phycobionts in contrast
to the very low genetic variability of the other coexisting phycobionts. Some of these haplotypes seemed to be
related to the colonization of specific phorophytes. The design of an additional marker based on sequences of
the psbA gene including group I introns was crucial to improve taxa recognition within the Trebouxia decolorans
complex in combination with others. From these results we conclude that the development of complementary
molecular markers may improve the recognition of different Trebouxia taxa within a single thallus when revising
lichen symbioses models. [MCINN (CGL2009-13429-C02-01/02), AECID (PCI_A_l024755/09) and Generalitat
Valenciana (PROMETEO 174/2008 GVA)]
(1I-P8) Submission ID: IAL0285-00001
GENETIC VARIABILITY OF CYANOBIONTS IN SOME PELTIGERA SPECIES
Resl P. 1 , Grube M. 1
1 Inst. of Plant Sciences, University of Graz, Graz, Austria
In this study the variation of Nostoc cyanobionts was studied in members of the lichen genus Peltigera.
Fragments of the 16S rRNA gene were analysed, as well as fragments of the NifH gene, belonging to the nitrogenfixiation
gene cluster. Using DNA fingerprinting technique SSCP (Single Strand Conformation Polymorphism) we
found the presence of multiple bands, indicating the non-uniformity of Nostoc cyanobionts incorporated in single
thalli. By sequencing of SSCP bands we further characterized the multiple cyanobacterial genotypes. We are
attempting to find correlating parameters for association with particular Nostoc strains and for their combined
presence. Photobiont association in Peltigera seems to be more flexible than previously thought.
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