1
duction pathway responsible for the recognition of both Nod factor and Myc factor. Repetitive oscillations in cytosolic calcium in root hair cells are one of the earliest plant responses to Nod factor and Myc factor, however the structure of the calcium response differs for these two signals. These calcium responses are embedded in the conserved symbiosis signalling pathway with a calcium/calmodulin dependent kinase (CCaMK) being apparently responsible for decoding both Myc factor and Nod factor induced calcium oscillations. Gain of function mutations in CCaMK activate nodulation without the need for Nod factor or rhizobial elicitation. This gain of function requires the activity of NSP1, NSP2 and ERN, all transcrip- tional activators. NSP1, NSP2 and ERN have specific functions in Nod factor signalling and represent a nodulation specific branch downstream of CCaMK. We propose that Nod factor induced calcium oscillations that occur in both the cytosol and the nucleus regulate the DMI3 kinase through a combination of calcium and calmodulin binding. DMI3 activates downstream components, including the transcriptional regulators NSP1, NSP2 and ERN. CCaMK must be able to discriminate between the Nod factor and Myc factor induced calcium oscillations and we presume that equivalent mycorrhizal specific components are induced under the appropriate conditions. doi:10.1016/j.cbpa.2007.01.471 P1.8 Polyketides and Pks genes in lichen-forming fungi: The impact of algal transfer metabolites (polyols and glucose) on the production of lichen substancesE. Stocker-Wörgötter, (University of Salzburg, Austria) Lichen-forming, ascomycetous fungi produce a broad spectrum of unique (only found in lichens!) and also common polyketides (pigments, occurring in several classes of fungi and also in higher plants). In summary, more than 1000 different lichen metabolites have been chemically identified. The majority of them are aromatic and aliphatic polyketides (including a few large ring compounds macrolides). Lichen metabolites have been screened by TLC and HPLC analyses; for a considerable number of them a strong biological activity has been recognised. One major objective of our research is to localise Pks genes by studying under which conditions a particular class of polyketides (e.g., depsides, depsidones, dibenzofurans, anthraquinones, etc.) is expressed in aposymbiotically cultured mycobionts. In extensive test series, it was shown that the compositions of the nutrient media (contents of algal transfer carbohydrates, sym- biosis products) influence and promote the expression of particular polyketides (e.g., depsides, depsidones, xanthones) in cultured mycobionts, compounds hitherto known only from intact lichens. It was repeatedly found that stable culture conditions led to the biosynthesis of fatty acids in form of fat droplets deposited on the surface of the mycelia, whereas environmental stresscaused a switch from fatty acid to polymalonate pathway and production of typical polyketides. The impact of the photobionts and their transfer metabolites on the production of polyketides will be discussed by comparing several symbiotic systems, di- partite, tri-partite and multiple partnerships among lichens and their in vitro resynthesis products. For one anthraquinone-producing lichen a gene bank for pks was successfully established. Progress in understanding the function of fungal type I Pkses and their control by Pks genes may revolutionise the use of lichens/cultured mycobionts in future biotechnological approaches, including heterologous expression of lichen pks genes in fast growing hosts and also the design of novel biological active molecules for pharmaceutical applications. doi:10.1016/j.cbpa.2007.01.472 P1.9 Interactions between insects and their symbiotic microorganisms A. Douglas, (York University, Canada) Obligate microbial symbionts are widespread or universal in several insect orders and include major agricultural or medical pests, e.g. blood-feeding lice, bedbugs and tsetse-fly, and plant sap-feeding aphids, planthoppers and whitefly. Our excellent understanding of the nutritional and protective roles of symbiotic microorganisms in insects has obtained from studies of the impact of antibiotic treatments (which eliminate the symbionts) on insect performance and physiology. The increasing availability of genome sequence data for the microbial symbionts and their insect insects provides new opportunities to address symbiotic interactions at the molecular level. I will explore the routes by which physiology and genomics are being integrated to obtain an understanding of insect interactions with their beneficial microorganisms, and to identify novel strategies in insect pest management. doi:10.1016/j.cbpa.2007.01.473 P1.10 Signalling of gene expression in rhizosphere bacteria Iron in the soil and sulphur in the seas A. Johnston, J. Todd, R. Rogers, N. Nikolaidou-Katsaridou, S. Li, A. Curson, (University of East Anglia, Norwich, United Kingdom) Nitrogen fixing legume root nodules are full of iron the plant- encoded leghaemoglobin and the bacterial nitrogenase and ancillary electron donors are all iron-containing proteins. Although we do not know the major sources of Fe for rhizobia in nodules, Fe acquisition by free-living rhizobia, in the soil and in the rhizosphere, has some unusual features. They have a wider S217 Abstracts / Comparative Biochemistry and Physiology, Part A 146 (2007) S215S223

Interactions between insects and their symbiotic microorganisms

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S217Abstracts / Comparative Biochemistry and Physiology, Part A 146 (2007) S215–S223

duction pathway responsible for the recognition of both Nodfactor and Myc factor. Repetitive oscillations in cytosoliccalcium in root hair cells are one of the earliest plant responsesto Nod factor and Myc factor, however the structure of thecalcium response differs for these two signals. These calciumresponses are embedded in the conserved symbiosis signallingpathway with a calcium/calmodulin dependent kinase(CCaMK) being apparently responsible for decoding bothMyc factor and Nod factor induced calcium oscillations. Gain offunction mutations in CCaMK activate nodulation without theneed for Nod factor or rhizobial elicitation. This gain of functionrequires the activity of NSP1, NSP2 and ERN, all transcrip-tional activators. NSP1, NSP2 and ERN have specific functionsin Nod factor signalling and represent a nodulation specificbranch downstream of CCaMK. We propose that Nod factorinduced calcium oscillations that occur in both the cytosol andthe nucleus regulate the DMI3 kinase through a combination ofcalcium and calmodulin binding. DMI3 activates downstreamcomponents, including the transcriptional regulators NSP1,NSP2 and ERN. CCaMK must be able to discriminate betweenthe Nod factor and Myc factor induced calcium oscillations andwe presume that equivalent mycorrhizal specific componentsare induced under the appropriate conditions.

doi:10.1016/j.cbpa.2007.01.471

P1.8Polyketides and Pks genes in lichen-forming fungi: Theimpact of algal transfer metabolites (polyols and glucose)on the production of “lichen substances”

E. Stocker-Wörgötter, (University of Salzburg, Austria)

Lichen-forming, ascomycetous fungi produce a broad spectrumof unique (only found in lichens!) and also common polyketides(pigments, occurring in several classes of fungi and also inhigher plants). In summary, more than 1000 different lichenmetabolites have been chemically identified. The majority ofthem are aromatic and aliphatic polyketides (including a fewlarge ring compounds — macrolides). Lichen metabolites havebeen screened by TLC and HPLC analyses; for a considerablenumber of them a strong biological activity has been recognised.One major objective of our research is to localise Pks genes bystudying under which conditions a particular class of polyketides(e.g., depsides, depsidones, dibenzofurans, anthraquinones, etc.)is expressed in aposymbiotically cultured mycobionts. Inextensive test series, it was shown that the compositions of thenutrient media (contents of algal transfer carbohydrates, “sym-biosis products”) influence and promote the expression ofparticular polyketides (e.g., depsides, depsidones, xanthones) inculturedmycobionts, compounds hitherto known only from intactlichens. It was repeatedly found that stable culture conditions ledto the biosynthesis of fatty acids in form of fat droplets depositedon the surface of the mycelia, whereas “environmental stress”caused a switch from fatty acid to polymalonate pathway and

production of typical polyketides. The impact of the photobiontsand their transfer metabolites on the production of polyketideswill be discussed by comparing several “symbiotic systems”, di-partite, tri-partite and multiple partnerships among lichens andtheir in vitro resynthesis products.For one anthraquinone-producing lichen a gene bank for pkswas successfully established.Progress in understanding the function of fungal type I Pksesand their control by Pks genes may revolutionise the use oflichens/cultured mycobionts in future biotechnologicalapproaches, including heterologous expression of lichen pksgenes in fast growing hosts and also the design of novelbiological active molecules for pharmaceutical applications.

doi:10.1016/j.cbpa.2007.01.472

P1.9Interactions between insects and their symbioticmicroorganisms

A. Douglas, (York University, Canada)

Obligate microbial symbionts are widespread or universal inseveral insect orders and include major agricultural or medicalpests, e.g. blood-feeding lice, bedbugs and tsetse-fly, and plantsap-feeding aphids, planthoppers and whitefly. Our excellentunderstanding of the nutritional and protective roles ofsymbiotic microorganisms in insects has obtained from studiesof the impact of antibiotic treatments (which eliminate thesymbionts) on insect performance and physiology. Theincreasing availability of genome sequence data for themicrobial symbionts and their insect insects provides newopportunities to address symbiotic interactions at the molecularlevel. I will explore the routes by which physiology andgenomics are being integrated to obtain an understanding ofinsect interactions with their beneficial microorganisms, and toidentify novel strategies in insect pest management.

doi:10.1016/j.cbpa.2007.01.473

P1.10Signalling of gene expression in rhizosphere bacteria —Iron in the soil and sulphur in the seas

A. Johnston, J. Todd, R. Rogers, N. Nikolaidou-Katsaridou,S. Li, A. Curson, (University of East Anglia, Norwich, UnitedKingdom)

Nitrogen fixing legume root nodules are full of iron— the plant-encoded leghaemoglobin and the bacterial nitrogenase andancillary electron donors are all iron-containing proteins.Although we do not know the major sources of Fe for rhizobiain nodules, Fe acquisition by free-living rhizobia, in the soil andin the rhizosphere, has some unusual features. They have a wider