Phosphate accumulation in rice leaves promotes fungal pathogenicity and represses host immune responses during pathogen infection
Martín-Cardoso, Héctor (Centre de Recerca en Agrigenòmica)
Bundó Barberà, Mireia (Centre de Recerca en Agrigenòmica)
Val-Torregrosa, Beatriz (Centre de Recerca en Agrigenòmica)
San Segundo, Blanca (Centre de Recerca en Agrigenòmica)

Data:	2024
Resum:	Rice is one of the most important crops in the world and a staple food for more than half of the world's population. At present, the blast disease caused by the fungus Magnaporthe oryzae poses a severe threat to food security through reduction of rice yields worldwide. High phosphate fertilization has previously been shown to increase blast susceptibility. At present, however, our knowledge on the mechanisms underpinning phosphate-induced susceptibility to M. oryzae infection in rice is limited. In this work, we conducted live cell imaging on rice sheaths inoculated with a M. oryzae strain expressing two fluorescently-tagged M. oryzae effectors. We show that growing rice under high phosphate fertilization, and subsequent accumulation of phosphate in leaf sheaths, promotes invasive growth of M. oryzae. Consistent with this, stronger expression of M. oryzae effectors and Pathogenicity Mitogen-activated Protein Kinase (PMK1) occurs in leaf sheaths of rice plants grown under high a phosphate regime. Down-regulation of fungal genes encoding suppressors of plant cell death and up-regulation of plant cell death-inducing effectors also occurs in sheaths of phosphate over-accumulating rice plants. Treatment with high Pi causes alterations in the expression of fungal phosphate transporter genes potentially contributing to pathogen virulence. From the perspective of the plant, Pi accumulation in leaf sheaths prevents HO accumulation early during M. oryzae infection which was associated to a weaker activation of Respiratory Burst Oxidase Homologs (RBOHs) genes involved in reactive oxygen species (ROS) production. Further, a weaker activation of defense-related genes occurs during infection in rice plants over-accumulating phosphate. From these results, it can be concluded that phosphate fertilization has an effect on the two interacting partners, pathogen and host. Phosphate-mediated stimulation of fungal effector genes (e. g. , potentiation of fungal pathogenicity) in combination with repression of pathogen-inducible immune responses (e. g. , ROS accumulation, defense gene expression) explains higher colonization by M. oryzae in rice tissues accumulating phosphate. Phosphate content can therefore be considered as an important factor in determining the outcome of the rice/ M. oryzae interaction. As fertilizers and pesticides are commonly used in rice cultivation to maintain optimal yield and to prevent losses caused by pathogens, a better understanding of how phosphate impacts blast susceptibility is crucial for developing strategies to rationally optimize fertilizer and pesticide use in rice production.
Ajuts:	Agencia Estatal de Investigación RTI2018-101275-B-I00 Agencia Estatal de Investigación PID2021-128825OB-I00 Ministerio de Ciencia e Innovación CEX2019-000902-S
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Blast ; Defense response ; Effectors ; Magnaporthe oryzae ; Oryza sativa ; Phosphate ; Reactive oxygen species
Publicat a:	Frontiers in plant science, Vol. 14 (January 2024) , art. 1330349, ISSN 1664-462X

DOI: 10.3389/fpls.2023.1330349
PMID: 38298608

20 p, 14.2 MB

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