Sidonie Bellot

Address

LMU Department für Biologie
Systematische Botanik und Mykologie
Menzinger Straße 67
80638 München
Germany

Contact

Fon:	+49 89 17861-228
Fax:	+49 89 172638
Email:
Room:	25, ground floor

Documents

Curriculum Vitae

Research interests and research curriculum

I am interested in what drives the perpetual changes encountered in the (biological) world. My research so far has focused on speciation in the Poaceae genus Spartina (Chloridoideae). In the lab of Professor Malika Aïnouche at the University of Rennes, I used next generation sequencing data (454) to reconstruct the plastid genome of the European species Spartina maritima and then compared it to the plastid genomes of other Poaceae. Such comparative analysis is a way to infer genome evolution based on the statistical analysis of nucleotide, amino acid, or gene changes. It is fascinating to observe the current state of an ancient endosymbiosis between a cyanobacteria and an eukaryote cell and the different progress of this symbiosis depending on the host lineage. Of course, such comparative analyses should ideally be accompanied by observations, hypotheses, and fieldwork or experiments on the biology of the focal organisms. The second goal of my work on Spartina was to choose plastid sequences to date diversification events in this genus. This gave new information concerning the origin and diversification of two hexaploid species originally distributed in two disjoint areas separated by the Atlantic Ocean, the American S. alterniflora and the European S. maritima. The hybridization of these two species in England at the end of the 19^th century resulted in the formation of a new dodecaploid species, S. anglica, which is highly invasive (Aïnouche et al., 2009). The influence of hybridization and/or polyploidy on the genomics, transcriptomics and invasive capacities of Spartina species or hybrids (see for instance Chelaifa et al., 2010) continue to be studied in the Aïnouche’s lab.
My work on the Spartina plastid genomes aroused my curiosity, and I would like to continue to study chloroplast evolution. I am currently thinking about focusing on a parasitic genus, Pilostyles (Apodanthaceae, Cucurbitales). In December 2010, I started a Ph.D. in the institute of Systematic Botany and Mycology at Ludwig-Maximilian University of Munich, under the supervision of Prof. Susanne Renner. My Ph.D. topic is not yet clearly defined but it could involve the study of the plastid genome of an Australian species of Pilostyles as described in the following summary.

Spartina maritima in Britanny

Britanny (France) in June 2010

Current Ph.D. project
Using next-generation-sequencing to study the organellar genomes of holoparasitic Pilostyles (Apodanthaceae) and to investigate horizontal gene exchange with its legume hosts

Most reports of natural horizontal gene transfer (HGT) in higher plants involve short fragments of mitochondrial DNA, usually taken up by parasitic species from their hosts (Bergthorsson et al., 2003, 2004; Won and Renner, 2003; Nickrent et al., 2004; Mower et al., 2004; Davis and Wurdack, 2004). The first case of HGT involving a nuclear gene also comes from a parasite, namely Striga hermonthica (Orobanchaceae) and its monocot crop host Sorghum bicolor (Yoshida, 2010). These findings indicate that cell-to-cell contact between species provides a route for gene flow throughout cell boundaries. The amount of DNA that can be transferred and its organellar location in the receiving organism have not been studied. This is because until recently, the required deep sequencing of host and parasite DNA was not feasible at reasonable expense, and suitable pairs of holoparasites and hosts were not readily available in cultivation. Parasitism is found in only a handful of families of flowering plants (Barkmann et al., 2007), each time involving the ability to uptake water and nutrients directly from host’s tissues through specialized feeding structures. Some parasitic plants have even lost the ability to photosynthesize and grow nearly completely embedded within the host tissues as so-called endoparasites, emerging only during sexual reproduction (i.e., these parasites never produce leaves). This is the case for the Apodanthaceae, a small family that is a research focus in the Renner lab (Filipowicz and Renner, 2010). It has been shown that Apodanthaceae belong in the Cucurbitales, and their organellar and nuclear genome can therefore in principle be compared to the completely sequenced genomes of several lines of Cucumis sativus.
In my doctoral research, I plan to use next-generation-sequencing to address questions about molecular evolution in the organellar genomes of the endoparasite Pilostyles hamiltonii. My detailed work plan is not yet clear, but I will probably focus on the chloroplast genome and the most common types of repetitive DNA. Little is known about the changes in the chloroplast genomes of holoparasitic, hemiparasitic, and autotrophic species, except for work on Epifagus virginiana (Orobanchaceae) (Wolfe et al., 1992a, b), Cuscuta (McNeal et al., 2007, Funk et al., 2007), and ongoing work by S. Wicke and G. Schneeweiss, who have characterized the patterns of gene loss, modification, and transfer in the chloroplasts of Orobanchaceae (Latvis et al., 2010; Wicke et al., 2010). The repetitive DNA is of interest because I would like to compare the most abundant types of transposons with those found by M. Piednoel, a postdoc in the Renner lab focusing on the repetitive DNA of Orobanchaceae (DFG-RE 603/9-1), in collaboration with G. Schneeweiss from the University of Vienna.
To bring the host plant into cultivation in Munich, I will visit our Australian collaborator, K. Dixon, during the summer of 2011, who is studying the germination conditions of P. hamiltonii.
My research will be the first ever such genome-level comparison and will provide insights both, into plastid genome evolution in holoparasites and into the extent of HGT between parasites and their hosts.
It could eventually be completed with observations on the physiology and the life cycle of Pilostyles hamiltonii and also on the impact of this parasitic plant on its host Daviesia angulata (Fabaceae) depending on the ecological conditions.

Pilostyles hamiltonii on Daviesia angulata in Australia, November 2009
Photo by Kingsley Dixon

References

Ainouche M.L., Fortune P.M., Salmon A., Parisod C., Grandbastien M.A., Fukunaga K., Ricou M. & Misset M.T. (2009): Hybridization, polyploidy and invasion: lessons from Spartina (Poaceae). Biol. Inv. 11(5) , 1159 – 1173

Bergthorsson U., Adams K.L., Thomason B., Palmer J.D. (2003): Widespread horizontal transfer of mitochondrial genes in flowering plants. Nature, 424:197 – 201.

Bergthorsson U., Richardson A.O., Young G.J., Goertzen L.R., Palmer J.D. (2004): Massive horizontal transfer of mitochondrial genes from diverse land plant donors to the basal angiosperm Amborella. Proceedings of the National Academy of Sciences of the United States of America, 101: 17747 – 17752.

Chelaifa H., Monnier A., Ainouche M. (2010): Transcriptomic changes following recent natural hybridization and allopolyploidy in the salt marsh species Spartina × townsendii and Spartina anglica (Poaceae). New Phytologist, 186: 161 – 174

Davis C.C., Wurdack K.J. (2004): Host-to-parasite gene transfer in flowering plants: phylogenetic evidence from Malpighiales. Science, 575: 676 – 678.

Filipowicz N., and Renner S.S. (2010): The worldwide holoparasitic Apodanthaceae confidently placed in the Cucurbitales by nuclear and mitochondrial gene trees. BMC Evolutionary Biology 10: 219

Funk H.T., Berg S., Krupinska K., Maier U.G. and Krause K. (2007): Complete DNA sequences of the plastid genomes of two parasitic flowering plant species, Cuscuta reflexa and Cuscuta gronovii. BMC Plant Biology, 7:45

Latvis M., Moore M., Wicke S., Soltis P., and Soltis D.E. (2010): How do different forms of parasitism within a family affect plastid genome structure? A comparison of the complete plastid genomes of Lindenbergia, Agalinis, and Epifagus. Botany

McNeal J.R., Kuehl J.V., Boore J.L. and de Pamphilis C.W. (2007): Complete plastid genome sequences suggest strong selection for retention of photosynthetic genes in the parasitic plant genus Cuscuta. BMC Plant Biology, 7:57

Mower J.P., Stefanovic S., Young G.J., Palmer J.D. (2004): Plant genetics: gene transfer from parasitic to host plants. Nature, 432:165 – 166.

Nickrent D.L., Blarer A., Qiu Y.L., Vidal-Russell R., Anderson F.E. (2004): Phylogenetic inference in Rafflesiales: the influence of rate heterogeneity and horizontal gene transfer. BMC Evolutionary Biology, 4:40.

Wicke S., Quandt D., Muller K.F., Wickett N.J., DePamphilis C.W., and Schneeweiss G.M. (2010): Plastid genome evolution – what’s so different between autotrophs, semi- and non-autotrophic flowering plants? Botany

Wolfe K.H., Morden C.W., Palmer J.D. (1992a): Function and evolution of a minimal plastid genome from a nonphotosynthetic parasitic plant. Proc. Natl. Acad. Sci. U.S.A. 89: 10648 – 10652.

Wolfe K.H., Morden C.W., Ems S.C., Palmer J.D. (1992b): Rapid evolution of the plastid translational apparatus in a nonphotosynthetic plant: loss or accelerated sequence evolution of tRNA and ribosomal protein genes. J. Mol. Evol. 35:304 – 317.

Won H., and Renner S.S. (2003): Horizontal gene transfer from flowering plants to Gnetum. Proceedings of the National Academy of Sciences, USA 100: 10824 – 10829.

Yoshida S., Maruyama S., Nozaki H. and Shirasu K. (2010): Horizontal gene transfer by the parasitic plant Striga hermonthica. Science 328: 1128.

Last update: 2011-01-17