Recent research highlights
Richard's truffle project
In an elegant combination of bioassays and chemical analytics Richard and his collaborators showed how the interplay of two plant hormones produced by truffle fungi modulates the morphology of plant roots, presumably conditioning the plant for colonization. Check the publication in Plant Physiology 150:2018-2029.
Update April 2010: Truffle genome sequenced
See comments on Nature paper co-authored by Richard.
Subhankar Chatterjee's insight into chemical interactions among fungi
Dr. Subhankar Chatterjee, Paramita Chatterjee
Subhankar investigates the role of secreted metabolites in interactions among fungi. He grews Aspergillus, Fusarium and Gliocladium in mixed cultures in different combinations and analyzes the metabolites which they produce by HPLC-MS. In order to distinguish the effect of the interaction on the synthesis of these metabolites (induction/suppression) from metabolic conversion (transformation to other compounds or complete degradation), he also combines mycelium of one fungus with solutions of metabolites produced by another fungi. Paramita supports him in the determination of the biomass of each fungus in mixed cultures. The first results show that there chemical interactions mediated by secondary metabolites are complex and the relative fitness of interacting fungal species cannot be described based on additive effects.
Diversity in Alternaria alternata
Azza Siddiq Abbo supported by Dr. Nayuf Valdez and Dr. Evelyn Möller
Azza already left the lab, unfortunately, she had only six months to stay with us. She was studying the diversity amoung A. alternata isolates from different host plants. She got beautiful data on genetic segregation along host specialization. We would like to know how this segregation is reflected at different levels of gene expression. The data will be compared with metabolic profiles which are currently recorded by Dr. Subhankar Chatterjee, with physiological data and virulence characteristics collected by Azza and possibly with the response of the isolates to certain metabolites extracted from the host plants, which is an issue investigated by Dr. Evelyn Möller.
Characterization of secondary metabolites produced by Azza's isolates by Dr. S. Chatterjee just began.
Virulence in Verticillium longisporum
Malte Beinhoff and Haiquan Xu, building on the results of Dr. Arne Weiberg
Malte and Haiquan continue their fruitful effort started by Arne Weiberg, who graduated and currently supports the plant part of the project, while he continues developing technical improvement for expression analysis (see below). Malte and Haiquan present their results at Verticillium meeting in Korfu in November. They silenced several candidate genes in the pathogen and found a dramatic reduction of virulence for two of them.
You may download their poster on VlNEP here.
Have a look at photos below: On the left uninoculated plants, in the middle plants inoculated with a wildtype strain, right one of the silenced mutants:
Chemical signaling in xylem
Dr. Astrid Ratzinger, continued by Husam Aroud
Astrid Ratzinger finished her PhD project on metabolic analysis of xylem sap of oilseed rape plants infected with vascular pathogen Verticillium longisporum. She discovered a couple of aparently novel metabolites which are currently further characterized by PhD student Husam Aroud. Astrid also discovered that xylem sap contains plant stress hormon salicylic acid (SA) and its glucose conjugate (SAG). So far it was only known that SA occurs in phloem. The reviewers suspected that our xylem sap was contaminated with phloem sap, which was the source of SA and SAG. Fortunately, phloem sap contains huge amoungs of sucrose which does not occur in xylem. Nadine Riediger determined the concentration of sucrose in our xylem sap preparations and calculated that the contamination with phloem was negligible. The paper was published in the Journal of Plant Research and you may download it from our publication website or directly from the publishers website, it is Open Access.
Husam continues Astrid's work by purifying infection-specific metabolites from large volumes of xylem sap. Currently he occupies all space in our phytochambers growing as many Brassica napus plants for infection with V. longisporum and xylem sap extraction as he can.
Further achievements
An incomplete and more or less random list of further results obtained in the lab in the last ten months:
Arne finished the second part of his technical analysis of electrophoresis-based transcriptomics techniques, publishing the results in Electrophoresis. This paper is Open Access, too, for which Wiley charged us US$ 3,000. We wanted to publish in Electrophophoresis because it is clearly the best journal for this kind of work, though we generally prefer genuine Open Access, web-based platforms.
Anke and her colleagues coauthorized a review on the replant disease of roses targeting a general audience. (Here is the link, it is a large pdf of 2.5 MB). Anke is currently looking for an MSc student to continue on the topic; she may start a larger effort in the project soon. She also guided the application of DGGE in two more projects. The first was carried out by Edilberto Montenegro (Panama/Costa Rica) on the suppressivness of soil in banana plantation. The second project was lead by Prof. Beate Michalzik, University Jena, and focused on microbial diversity in a forest heavily infested with larvae of an insect pest. Both studies require extensive data processing before the data can be published. Furthemore, Anke lead and effort to publish a technical review on auxin production in symbiotic fungi (check our publication list).
Sasithorn "Joy" Limsuwan and Patricia Bartoschek, occasionally supported by Katharina Döll and others, delivered vast amounts of data on mycotoxin content and Fusarium spp. biomass in field samples produced by the participants of the FAEN project. The first data have been written down for publication, further data are being processed. Our mycotoxin analysis lab never stop being filled with samples: freeze-dried Asparagus shoots, rice cultures, liquid fungal cultures, wheat flower, maize roots...
Subhankar is generating huge amounts of metabolic data on fungus-fungus interactions. He got support from Paramita on biomass estimation, which he needs for normalization. Data processing remains a challenge. At least our ion trap is working well again, after a disastrous contamination with oil leaking from onoe of the rough pumps. Check our 500-MS website, we will post detals soon.
Sabine is processing her data and writing a thesis and manuscripts. Hopefully she is only writing, nothing else. She has a lot to write, will be quite busy in the remaining months if no valuable data should be vasted...
Awais is still running experiments though his time is getting thinner, too. He is getting all the support he needs, becuase the data are so good that we want to have them all and he does not have that much time any more. In the moment he works mainly with Jacqueline.
Rehana ramified her work from antifungal effect of sesame metabolites to phytohormone homeostasis. But her RILs from a segregating population of a sesame cross are ready or nearly ready! She processed 110 lines over 6 generations of selfing without loosing any. F6 seeds are maturating and will be harvested next month. In January she can start growing F7 plants, for the first time not just for selfing but for real experiments.
Nayuf is writing her thesis, too. There are still some endophytes isolated from her tropical trees waiting to be characterized, but this will not stop her from finishing the writing, followed by submission and a defense. We will surely feel lonely after all these brilliant PhDs have left us next spring and sumner...
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