Ane Sesma

Publications of Ane Sesma

• Genetic evidence for natural product-mediated plant-plant allelopathy in rice (Oryza sativa).

  Authors: Meimei Xu, Rita Galhano, Philipp Wiemann, Emilio Bueno, Mollie Tiernan, William Wu, Ill-Min Chung, Jonathan Gershenzon, Bettina Tudzynski, Ane Sesma, Reuben J Peters

  The New phytologist. 12/2011; 193(3):570-5.

  • There is controversy as to whether specific natural products play a role in directly mediating antagonistic plant-plant interactions - that is, allelopathy. If proved to exist, such phenomena would• There is controversy as to whether specific natural products play a role in directly mediating antagonistic plant-plant interactions - that is, allelopathy. If proved to exist, such phenomena would hold considerable promise for agronomic improvement of staple food crops such as rice (Oryza sativa). • However, while substantiated by the presence of phytotoxic compounds at potentially relevant concentrations, demonstrating a direct role for specific natural products in allelopathy has been difficult because of the chemical complexity of root and plant litter exudates. This complexity can be bypassed via selective genetic manipulation to ablate production of putative allelopathic compounds, but such an approach previously has not been applied. • The rice diterpenoid momilactones provide an example of natural products for which correlative biochemical evidence has been obtained for a role in allelopathy. Here, we apply reverse genetics, using knock-outs of the relevant diterpene synthases (copalyl diphosphate synthase 4 (OsCPS4) and kaurene synthase-like 4 (OsKSL4)), to demonstrate that rice momilactones are involved in allelopathy, including suppressing growth of the widespread rice paddy weed, barnyard grass (Echinochloa crus-galli). • Thus, our results not only provide novel genetic evidence for natural product-mediated allelopathy, but also furnish a molecular target for breeding and metabolic engineering of this important crop plant.

• Fungal virulence and development is regulated by alternative pre-mRNA 3'end processing in Magnaporthe oryzae.

  Authors: Marina Franceschetti, Emilio Bueno, Richard A Wilson, Sara L Tucker, Concepción Gómez-Mena, Grant Calder, Ane Sesma

  PLoS pathogens. 12/2011; 7(12):e1002441.

  RNA-binding proteins play a central role in post-transcriptional mechanisms that control gene expression. Identification of novel RNA-binding proteins in fungi is essential to unravelRNA-binding proteins play a central role in post-transcriptional mechanisms that control gene expression. Identification of novel RNA-binding proteins in fungi is essential to unravel post-transcriptional networks and cellular processes that confer identity to the fungal kingdom. Here, we carried out the functional characterisation of the filamentous fungus-specific RNA-binding protein RBP35 required for full virulence and development in the rice blast fungus. RBP35 contains an N-terminal RNA recognition motif (RRM) and six Arg-Gly-Gly tripeptide repeats. Immunoblots identified two RBP35 protein isoforms that show a steady-state nuclear localisation and bind RNA in vitro. RBP35 coimmunoprecipitates in vivo with Cleavage Factor I (CFI) 25 kDa, a highly conserved protein involved in polyA site recognition and cleavage of pre-mRNAs. Several targets of RBP35 have been identified using transcriptomics including 14-3-3 pre-mRNA, an important integrator of environmental signals. In Magnaporthe oryzae, RBP35 is not essential for viability but regulates the length of 3'UTRs of transcripts with developmental and virulence-associated functions. The Δrbp35 mutant is affected in the TOR (target of rapamycin) signaling pathway showing significant changes in nitrogen metabolism and protein secretion. The lack of clear RBP35 orthologues in yeast, plants and animals indicates that RBP35 is a novel auxiliary protein of the polyadenylation machinery of filamentous fungi. Our data demonstrate that RBP35 is the fungal equivalent of metazoan CFI 68 kDa and suggest the existence of 3'end processing mechanisms exclusive to the fungal kingdom.

• Common genetic pathways regulate organ-specific infection-related development in the rice blast fungus.

  Authors: Sara L Tucker, Maria I Besi, Rita Galhano, Marina Franceschetti, Stephan Goetz, Steven Lenhert, Anne Osbourn, Ane Sesma

  The Plant cell. 03/2010; 22(3):953-72.

  Magnaporthe oryzae is the most important fungal pathogen of rice (Oryza sativa). Under laboratory conditions, it is able to colonize both aerial and underground plant organs using differentMagnaporthe oryzae is the most important fungal pathogen of rice (Oryza sativa). Under laboratory conditions, it is able to colonize both aerial and underground plant organs using different mechanisms. Here, we characterize an infection-related development in M. oryzae produced on hydrophilic polystyrene (PHIL-PS) and on roots. We show that fungal spores develop preinvasive hyphae (pre-IH) from hyphopodia (root penetration structures) or germ tubes and that pre-IH also enter root cells. Changes in fungal cell wall structure accompanying pre-IH are seen on both artificial and root surfaces. Using characterized mutants, we show that the PMK1 (for pathogenicity mitogen-activated protein kinase 1) pathway is required for pre-IH development. Twenty mutants with altered pre-IH differentiation on PHIL-PS identified from an insertional library of 2885 M. oryzae T-DNA transformants were found to be defective in pathogenicity. The phenotypic analysis of these mutants revealed that appressorium, hyphopodium, and pre-IH formation are genetically linked fungal developmental processes. We further characterized one of these mutants, M1373, which lacked the M. oryzae ortholog of exportin-5/Msn5p (EXP5). Mutants lacking EXP5 were much less virulent on roots, suggesting an important involvement of proteins and/or RNAs transported by EXP5 during M. oryzae root infection.

• Gene deletion of 7,8-linoleate diol synthase of the rice blast fungus. Studies on pathogenicity, stereochemistry, and oxygenation mechanisms.

  Authors: Fredrik Jerneren, Ane Sesma, Marina Francheschetti, Mats Hamberg, Ernst H Oliw

  The Journal of biological chemistry. 12/2009;

  Linoleate diol synthases (LDS) are heme enzymes, which oxygenate 18:2n-6 sequentially to 8(R)-hydroperoxylinoleic acid (8R-HPODE) and to 5(S),8(R)-dihydroxy-, 7(S),8(S)-dihydroxy-, orLinoleate diol synthases (LDS) are heme enzymes, which oxygenate 18:2n-6 sequentially to 8(R)-hydroperoxylinoleic acid (8R-HPODE) and to 5(S),8(R)-dihydroxy-, 7(S),8(S)-dihydroxy-, or 8(R),11(S)-dihydroxylinoleic acids (DiHODE). The genome of the rice blast fungus, Magnaporthe oryzae, contains two genes with homology to LDS. M. oryzae oxidized 18:2n-6 to 8R-HPODE and to 7S,8S-DiHODE, 6S,8R-DiHODE, and 8R,11S-HODE. Small amounts of 10-HODE and traces of 5,8-DiHODE were also detected by liquid chromatography-mass spectrometry. The contribution of 7,8-LDS gene to M. oryzae pathogenicity was evaluated by replacement of the catalytic domain with hygromycin and green fluorescent protein (sGFP) cassettes. This genetically modified strain (Delta7,8-LDS) infected rice leaves and roots and formed appressoria and conidia as the native fungus. The Delta7,8-LDS mutant had lost the capacity to biosynthesize all the metabolites except small amounts of 8-HODE. Studies with stereospecifically deuterated linoleic acids showed that 8R-HPODE was formed by abstraction of the pro-S hydrogen at C-8 and antarafacial oxygenation, whereas 7S,8S-DiHODE and 8R,11S-DiHODE were formed from 8R-HPODE by suprafacial hydrogen abstraction and oxygenation at C-7 and C-11, respectively. A mac1 suppressor mutant (mac1 sum1-99) of M. oryzae which shows cAMP-independent protein kinase A (PKA) activity, oxygenated 18:2n-6 to increased amounts of 10R-HPODE and 5S,8R-DiHODE. Expression of the 7,8-LDS gene but not of the second homologue was detected in the suppressor mutant. This suggests that PKA-mediated signaling pathway regulates the dioxygenase and hydroperoxide isomerase activities of M. oryzae.

• Capillary-induced contact guidance.

  Authors: Steven Lenhert, Ane Sesma, Michael Hirtz, Lifeng Chi, Harald Fuchs, Hans-Peter Wiesmann, Anne E Osbourn, Bruno M Moerschbacher

  Langmuir : the ACS journal of surfaces and colloids. 10/2007; 23(20):10216-23.

  Topographical features are known to impose capillary forces on liquid droplets, and this phenomenon is exploited in applications such as printing, coatings, textiles and microfluidics. SurfaceTopographical features are known to impose capillary forces on liquid droplets, and this phenomenon is exploited in applications such as printing, coatings, textiles and microfluidics. Surface topographies also influence the behavior of biological cells (i.e., contact guidance), with implications ranging from medicine to agriculture. An accurate physical description of how cells detect and respond to surface topographies is necessary in order to move beyond a purely heuristic approach to optimizing the topographies of biomaterial interfaces. Here, we have used a combination of Langmuir-Blodgett lithography and nanoimprinting to generate a range of synthetic microstructured surfaces with grooves of subcellular dimensions in order to investigate the influence of capillary forces on the biological process of contact guidance. The physical-chemical properties of these surfaces were assessed by measuring the anisotropic spreading of sessile water droplets. Having established the physical properties of each surface, we then investigated the influence of capillary forces on the processes of cellular contact guidance in biological organisms, using mammalian osteoblasts and germinating fungal spores as tester organisms. Our results demonstrate that capillary effects are present in topographical contact guidance and should therefore be considered in any physical model that seeks to predict how cells will respond to a particular surface topography.

• Comparative transcriptomics of rice reveals an ancient pattern of response to microbial colonization.

  Authors: Sonia Güimil, Hur-Song Chang, Tong Zhu, Ane Sesma, Anne Osbourn, Christophe Roux, Vassilios Ioannidis, Edward J Oakeley, Mylène Docquier, Patrick Descombes, Steven P Briggs, Uta Paszkowski

  Proceedings of the National Academy of Sciences of the United States of America. 06/2005; 102(22):8066-70.

  Glomalean fungi induce and colonize symbiotic tissue called arbuscular mycorrhiza on the roots of most land plants. Other fungi also colonize plants but cause disease not symbiosis.Glomalean fungi induce and colonize symbiotic tissue called arbuscular mycorrhiza on the roots of most land plants. Other fungi also colonize plants but cause disease not symbiosis. Whole-transcriptome analysis using a custom-designed Affymetrix Gene-Chip and confirmation with real-time RT-PCR revealed 224 genes affected during arbuscular mycorrhizal symbiosis. We compared these transcription profiles with those from rice roots that were colonized by pathogens (Magnaporthe grisea and Fusarium moniliforme). Over 40% of genes showed differential regulation caused by both the symbiotic and at least one of the pathogenic interactions. A set of genes was similarly expressed in all three associations, revealing a conserved response to fungal colonization. The responses that were shared between pathogen and symbiont infection may play a role in compatibility. Likewise, the responses that are different may cause disease. Some of the genes that respond to mycorrhizal colonization may be involved in the uptake of phosphate. Indeed, phosphate addition mimicked the effect of mycorrhiza on 8% of the tested genes. We found that 34% of the mycorrhiza-associated rice genes were also associated with mycorrhiza in dicots, revealing a conserved pattern of response between the two angiosperm classes.

• The rice leaf blast pathogen undergoes developmental processes typical of root-infecting fungi.

  Authors: Ane Sesma, Anne E Osbourn

  Nature. 10/2004; 431(7008):582-6.

  Pathogens have evolved different strategies to overcome the various barriers that they encounter during infection of their hosts. The rice blast fungus Magnaporthe grisea causes one of the mostPathogens have evolved different strategies to overcome the various barriers that they encounter during infection of their hosts. The rice blast fungus Magnaporthe grisea causes one of the most damaging diseases of cultivated rice and has emerged as a paradigm system for investigation of foliar pathogenicity. This fungus undergoes a series of well-defined developmental steps during leaf infection, including the formation of elaborate penetration structures (appressoria). This process has been studied in great detail, and over thirty M. grisea genes that condition leaf infection have been identified. Here we show a new facet of the M. grisea life cycle: this fungus can undergo a different (and previously uncharacterized) set of programmed developmental events that are typical of root-infecting pathogens. We also show that root colonization can lead to systemic invasion and the development of classical disease symptoms on the aerial parts of the plant. Gene-for-gene type specific disease resistance that is effective against rice blast in leaves also operates in roots. These findings have significant implications for fungal development, epidemiology, plant breeding and disease control.