Our research
Global food security is seriously affected by fungal pathogens of the Magnaporthaceae family. Two of the most damaging fungal pathogens affecting staple foods such as rice and wheat belong to this family: the rice blast fungus, Magnaporthe oryzae, which also causes a very serious disease in wheat, and the causal agent of take-all disease of wheat, Gaeumannomyces graminis. Our main research interests focus on the identification of post-transcriptional mechanisms regulating infection-related processes in the rice blast fungus. Our knowledge on the function of RNA-binding proteins and RNA pathways regulating fungal infection of plants and animals is very limited. Identification of novel RNA-binding proteins is essential to increase our knowledge on RNA networks and cellular processes involved in M. oryzae infection biology. |
Fig. 1. M. oryzae penetrates the stele. Confocal imaging of radial sections of a two-week-old rice (left) and barley (right) seedlings infected with GFP-tagged M. oryzae. M. oryzae can undergo a different set of developmental events that are typical of root-infecting pathogens (Sesma & Osbourn, Nature 2014; Tucker et al., Plant Cell 2010) |
The RNA-binding protein Rbp35 regulates the length of 3’UTRs of transcripts with developmental and virulence-associated functions in M. oryzae. We have characterised the RNA-binding protein Rbp35, a component of the polyadenylation machinery involved in the modification of 3’UTR lengths of infection-related genes (Franceschetti et al, PLoS Pathogens 2011). The expression of Rbp35 protein itself is under strict control, which indicates that Rbp35 is a key regulator of the fungal cell (Rodríguez-Romero et al, Nuc. Ac. Res. 2015). 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.
We also found that different classes of sRNAs are altered in the nucleo-cytoplasmic receptor Exp5 (Tucker et al. 2010) and Rbp35, which suggests that in addition to other functions, these two proteins participate in different small RNA biogenesis pathways.
Fig. 2. RNA metabolism is controlled by RNA-binding proteins which play a crucial role in a number of steps between de novo transcription and protein synthesis.
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Organ-specific infection mechanisms. The recognition of plant cell surfaces (leaves/roots) leads to the development of different infection structures (appressoria or hyphopodia) before fungal penetration. It is not known if the hyphopodium is an intermediate step that takes place before the formation of a mature appressorium or is an independent developmental process. Several approaches including lectin cytochemistry, gene expression analysis of infection-related genes and well characterised mutants were used for a detailed analysis of this morphogenetic development. Our results reveal genetic commonalities between appressorium and hyphopodium differentiation suggesting that hyphopodia could represent primitive appressoria. Thus, hyphopodium formation is likely to be an intermediate step before mature appressorium development (Tucker et al, 2010). |
Research projects
- Post-transcriptional regulation in response to environmental stress in the rice blast fungus MINECO, 2015- 2018. PI: Ane Sesma.
- Understanding translation regulation to improve plants adaptation to biotic and abiotic stresses 2014- 2018 (Community of Madrid / EU). PIs: Ane Sesma (CBGP/UPM), Carmen Castresana (CNB/CSIC), and Mar Castellano (INIA, coordinator).
- Post-transcriptional networks regulating organ-specific and general infection mechanisms in the rice blast fungus. Marie Curie Reintegration grant 2012- 2016 (FP7-2011-CIG). PI: Ane Sesma.
- Exploring infection mechanisms in the rice blast fungus Magnaporthe oryzae. MICINN, 2011- 2015. PI: Ane Sesma.
- Dissection of distinct pathogenesis-related developmental processes in the rice blast fungus Magnaporthe grisea. David Philips BBSRC fellowship, 2005-2010. PI: Ane Sesma.
