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Photochem Photobiol Sci ; 17(1): 8-17, 2018 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-29110008


The traditional rice variety "Baijiaolaojing" was planted in Yuanyang terraces (1600 m altitude) under field conditions. The effects of enhanced UV-B radiation (0 kJ m-2, 2.5 kJ m-2, 5.0 kJ m-2 and 7.5 kJ m-2) on the rice-Magnaporthe oryzae system were studied with respect to the Magnaporthe oryzae infection, the disease-resistance physiology of the rice and the rice blast disease condition. The results showed that under enhanced UV-B radiation, the infectivity of Magnaporthe oryzae was decreased, which could significantly inhibit its growth and sporulation. The activities of rice leaf disease-resistance-related enzymes (phenylalanine ammonia-lyase, lipoxygenase, chitinase and ß-1,3-glucanase) were significantly increased under enhanced UV-B radiation. Following inoculation with Magnaporthe oryzae, levels of disease-resistance-related substances in the rice leaves were significantly increased. Among the results, it was found that leaves after UV-B radiation had a more significant resistance response. The level of UV-B irradiation showed a parabolic relationship with the rice blast index (r2 = 0.85, P < 0.01; in the control group, r2 = 0.88, P < 0.01). The disease index decreased with increase in irradiation. The DI was at a minimum with enhanced UV-B irradiance of 4 kJ m-2; thereafter, it increased with increasing irradiation. The enhanced UV-B radiation had a direct impact on the growth of rice and Magnaporthe oryzae, and it indirectly changed the rice-Magnaporthe oryzae system. UV-B radiation could reduce the harmful impact of rice blast.

Resistência à Doença/efeitos da radiação , Magnaporthe/patogenicidade , Magnaporthe/efeitos da radiação , Oryza/microbiologia , Oryza/efeitos da radiação , Doenças das Plantas/microbiologia , Raios Ultravioleta , China , Magnaporthe/enzimologia , Magnaporthe/metabolismo
Autophagy ; 13(8): 1318-1330, 2017 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-28594263


Magnaporthe oryzae, the ascomycete fungus that causes rice blast disease, initiates conidiation in response to light when grown on Prune-Agar medium containing both carbon and nitrogen sources. Macroautophagy/autophagy was shown to be essential for M. oryzae conidiation and induced specifically upon exposure to light but is undetectable in the dark. Therefore, it is inferred that autophagy is naturally induced by light, rather than by starvation during M. oryzae conidiation. However, the signaling pathway(s) involved in such phototropic induction of autophagy remains unknown. We identified an M. oryzae ortholog of GCN5 (MGG_03677), encoding a histone acetyltransferase (HAT) that negatively regulates light- and nitrogen-starvation-induced autophagy, by acetylating the autophagy protein Atg7. Furthermore, we unveiled novel regulatory mechanisms on Gcn5 at both transcriptional and post-translational levels, governing its function associated with the unique phototropic response of autophagy in this pathogenic fungus. Thus, our study depicts a signaling network and regulatory mechanism underlying the autophagy induction by important environmental clues such as light and nutrients.

Autofagia , Biocatálise , Proteínas Fúngicas/metabolismo , Magnaporthe/citologia , Magnaporthe/metabolismo , Processos Fototróficos , Acetilação , Autofagia/efeitos da radiação , Regulação Fúngica da Expressão Gênica/efeitos da radiação , Genes Fúngicos , Luz , Magnaporthe/genética , Magnaporthe/efeitos da radiação , Processos Fototróficos/efeitos da radiação , Ligação Proteica , Processamento de Proteína Pós-Traducional/efeitos da radiação , Esporos Fúngicos/metabolismo , Esporos Fúngicos/efeitos da radiação , Transcrição Genética/efeitos da radiação
Fungal Biol ; 118(8): 743-53, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-25110136


Many environmental factors, alone or combined, affect organisms by changing a pro-/antioxidant balance. Here we tested rice blast fungus (Magnaporthe oryzae) for possible cross-adaptations caused by relatively intense light and protecting from artificially formed reactive oxygen species (ROS) and ROS-dependent fungitoxic response of the host plant. Spore germination was found to be suppressed under 4-h and, to larger extent, 5-h illumination. The effect was diminished by antioxidants and, therefore, suggests involvement of ROS. One-hour of light did not affect spore germination, but stimulated their chemically assayed superoxide production. The illuminated spores were more tolerant (than non-illuminated ones) to artificially generated H(2)O(2), O(2)(-), or OH or to toxic diffusate of rice leaf. They also caused more severe disease symptoms if applied to leaves of the susceptible rice cultivar at low concentration. Spore diffusates decomposed hydrogen peroxide. They detoxified exogenous H(2)O(2) and superoxide radical as well as leaf diffusates. Spore illumination increased some of these protective effects. It is suggested that short-term light led to mild oxidative stress, which induced spore antioxidant capacity, enhancing spore tolerance to subsequent stronger oxidative stress and its aggressiveness in planta. Such tolerance depends partly on the antidotal action of spore extracellular compounds, which may also be light-stimulated. Therefore, a certain ROS-related environmental factor may adapt a fungus to other factors and so modulate its pathogenic properties.

Luz , Magnaporthe/fisiologia , Magnaporthe/efeitos da radiação , Estresse Oxidativo , Esporos Fúngicos/fisiologia , Esporos Fúngicos/efeitos da radiação , Tolerância a Medicamentos , Oryza/microbiologia , Oxidantes/toxicidade , Doenças das Plantas/microbiologia
Fungal Genet Biol ; 43(10): 694-706, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16765070


Light is a major environmental factor that influences many biological processes. We characterized the roles of light in asexual development (including the formation of aerial hyphae and conidiophore) in Magnaporthe oryzae, which is the causal agent of rice blast disease. Our data revealed a complex nature of light regulation in the asexual developments of M. oryzae. Asexual development of M. oryzae is suppressed by blue light in a light/dark cycling environment and asexual spore release is controlled by both blue and red light. We demonstrated that even very dim light, about 10 micromol m(-2), is sufficient to suppress spore-release behavior in M. oryzae. We also generated knockout strains of a blue light receptor, mgwc-1, the M. oryzae homolog of white collar-1 in Neurospora crassa, and demonstrated blue-light-specific regulation in the asexual development and spore release in M. oryzae. Our findings in this agriculturally important pathogen, M. oryzae, broaden our understanding of the roles of light in fungal development.

Luz , Magnaporthe/efeitos da radiação , Oryza/microbiologia , Southern Blotting , Proteínas Fúngicas/genética , Regulação Fúngica da Expressão Gênica/efeitos da radiação , Hifas/genética , Hifas/crescimento & desenvolvimento , Hifas/efeitos da radiação , Magnaporthe/genética , Magnaporthe/fisiologia , Mutação/genética , Fotorreceptores Microbianos/genética , Reação em Cadeia da Polimerase , Reprodução Assexuada/genética , Esporos Fúngicos/genética , Esporos Fúngicos/crescimento & desenvolvimento , Esporos Fúngicos/efeitos da radiação
Biotechnol Lett ; 25(22): 1941-4, 2003 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-14719830


Genomic DNA was isolated from as little as 2 mg dry biomass of Magnaporthe grisea by microwave treatment within 30 s. The quantity of DNA was good enough for PCR analysis and Dot blot hybridization. This technique can be used for various studies, such as DNA fingerprinting to study the population structure of the phytopathogen in different regions, and for a quick screening of M. grisea transformants.

DNA Fúngico/química , DNA Fúngico/isolamento & purificação , Magnaporthe/química , Magnaporthe/efeitos da radiação , Microquímica/métodos , Micro-Ondas , Relação Dose-Resposta à Radiação , Campos Eletromagnéticos , Magnaporthe/genética , Magnaporthe/isolamento & purificação , Doses de Radiação