Biology subjects

Oses-Ruiz, M.

Publications and source records attributed to Oses-Ruiz, M..

5 recordsLinked to original sources

bioRxiv2025

Synchronous spatio-temporal control of autophagy and organelle trafficking is necessary for appressorium-mediated plant infection by Magnaporthe oryzae

The blast fungus Magnaporthe oryzae infects plants using a specialised infection structure called an appressorium that generates physical force to break the rice leaf cuticle. Appressorium development follows a cell cycle-controlled morphogenetic program, requiring autophagy-associated cell death of the fungal spore from which the infection cell develops. How proliferative growth of the fungus is regulated at the same time as programmed cell death, however, is unknown. In this study, we provide evidence that each cell of the conidium undergoes a separate developmental program, which is necessary for plant infection. Using quantitative live-cell imaging, we monitored trafficking of ten organelle types during appressorium morphogenesis in a wild-type M. oryzae strain and isogenic {Delta}atg8 autophagic mutant. High-resolution microscopy using a photoactivatable green fluorescent protein revealed that organelle trafficking occurs from a single conidium cell into the appressorium, while the remaining two cells undergo autophagy. Organelle inheritance operates independently of cell cycle checkpoints but is always associated with spore germination. We furthermore defined the temporal sequence of organelle movement and de novo organelle biogenesis in the incipient appressorium using photoconvertible fluorescent localisation microscopy. Taken together, our study reveals how synchronous spatiotemporal control of autophagy and organelle trafficking is necessary for rice blast infection.

molecular biology↗

bioRxiv2023

The phosphorylation landscape of infection-related development by the rice blast fungus

Many of the worlds most devastating crop diseases are caused by fungal pathogens which elaborate specialized infection structures to invade plant tissue. Here we present a quantitative mass spectrometry-based phosphoproteomic analysis of infection-related development by the rice blast fungus Magnaporthe oryzae, which threatens global food security. We mapped 8,005 phosphosites on 2,062 fungal proteins, revealing major re-wiring of phosphorylation-based signaling cascades during fungal infection. Comparing phosphosite conservation across 41 fungal species reveals phosphorylation signatures specifically associated with biotrophic and hemibiotrophic fungal infection. We then used parallel reaction monitoring to identify phosphoproteins directly regulated by the Pmk1 MAP kinase that controls plant infection by M. oryzae. We define 33 substrates of Pmk1 and show that Pmk1-dependent phosphorylation of a newly identified regulator, Vts1, is required for rice blast disease. Defining the phosphorylation landscape of infection therefore identifies potential therapeutic interventions for control of plant diseases.

plant biology↗

bioRxiv2022

The transcriptional landscape of plant infection by the rice blast fungus Magnaporthe oryzae reveals distinct families of temporally co-regulated and structurally conserved effectors

The rice blast fungus Magnaporthe oryzae causes a devastating disease which threatens global rice production. In spite of intense study, the biology of plant tissue invasion during blast disease remains poorly understood. Here we report a high resolution, transcriptional profiling study of the entire plant-associated development of the blast fungus. Our analysis revealed major temporal changes in fungal gene expression during plant infection. Pathogen gene expression could be classified into 10 modules of temporally co-expressed genes, providing evidence of induction of pronounced shifts in primary and secondary metabolism, cell signalling and transcriptional regulation. A set of 863 genes encoding secreted proteins are differentially expressed at specific stages of infection, and 546 were predicted to be effectors and named MEP (Magnaporthe effector protein) genes. Computational prediction of structurally-related MEPs, including the MAX effector family, revealed their temporal co-regulation in the same co-expression modules. We functionally characterised 32 MEP genes and demonstrate that Mep effectors are predominantly targeted to the cytoplasm of rice cells via the biotrophic interfacial complex (BIC), and use a common unconventional secretory pathway. Taken together, our study reveals major changes in gene expression associated with blast disease and identifies a diverse repertoire of effectors critical to successful infection.

plant biology↗

bioRxiv2020

Chitosan inhibits septin-mediated plant infection by the rice blast fungus Magnaporthe oryzae in a Protein Kinase C and Nox1 NADPH oxidase-dependent manner

O_LIChitosan is a partially deacetylated linear polysaccharide composed of {beta}-1,4-linked units of D-glucosamine and N-acetyl glucosamine. As well as acting as a structural component of fungal cell walls, chitosan can be applied as a potent antifungal agent. However, the mode-of-action of chitosan in fungal pathogens is poorly understood. C_LIO_LIHere, we report that chitosan is effective for control of rice blast disease. Chitosan application impairs growth of the blast fungus Magnaporthe oryzae and has a pronounced effect on appressorium-mediated plant infection. Chitosan inhibits septin-mediated F-actin re-modelling at the appressorium pore, thereby preventing re-polarisation of the infection cell and rice leaf cuticle penetration. C_LIO_LIWe found that chitosan causes plasma membrane permeabilization of M. oryzae and affects NADPH oxidase-dependent synthesis of reactive oxygen species, essential for septin ring formation and fungal pathogenicity. Our data further show that the toxicity of chitosan to M. oryzae requires the protein kinase C-dependent cell wall integrity pathway and the Nox1 NADPH oxidase. A conditionally lethal, analogue (PP1)-sensitive mutant of Pkc1 is partially remediated for growth in the presence of chitosan and PP1, while {Delta}nox1 mutants increase their glucan/chitin cell wall ratio, rendering them resistant to chitosan. C_LIO_LITaken together, our data show that chitosan is a potent fungicide for control of the rice blast fungus which involves the cell wall integrity pathway, disrupts plasma membrane and inhibits septin-mediated plant infection. C_LI

plant biology↗

bioRxiv2020

A hierarchical transcriptional network controls appressorium-mediated plant infection by the rice blast fungus Magnaporthe oryzae

Rice blast is a pervasive and devastating disease that threatens rice production across the world. In spite of its importance to global food security, however, the underlying biology of plant infection by the blast fungus Magnaporthe oryzae remains poorly understood. In particular, it is unclear how the fungus elaborates a specialised infection cell, the appressorium, in response to surface signals from the rice leaf. Here, we report the identification of a network of temporally co-regulated transcription factors that act downstream of the Pmk1 mitogen-activated protein kinase pathway to regulate gene expression during appressorium-mediated plant infection. We have functionally characterised this network of transcription factors and demonstrated the operation of a hierarchical transcriptional control system. We show that this tiered regulatory mechanism involves Pmk1-dependent phosphorylation of the Hox7 homeobox transcription factor, which represses hyphal-associated gene expression and simultaneously induces major physiological changes required for appressorium development, including cell cycle arrest, autophagic cell death, turgor generation and melanin biosynthesis. Mst12 then regulates gene functions involved in septin-dependent cytoskeletal re-organisation, polarised exocytosis and effector gene expression necessary for plant tissue invasion.

microbiology↗