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1.
Mol Plant Pathol ; 20(8): 1147-1162, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31218796

RESUMO

Magnaporthe oryzae causes blast disease, which is one of the most devastating infections in rice and several important cereal crops. Magnaporthe oryzae needs to coordinate gene regulation, morphological changes, nutrient acquisition and host evasion in order to invade and proliferate within the plant tissues. Thus far, the molecular mechanisms underlying the regulation of invasive growth in planta have remained largely unknown. We identified a precise filamentous-punctate-filamentous cycle in mitochondrial morphology during Magnaporthe-rice interaction. Interestingly, disruption of such mitochondrial dynamics by deletion of genes regulating either the mitochondrial fusion (MoFzo1) or fission (MoDnm1) machinery, or inhibition of mitochondrial fission using Mdivi-1 caused significant reduction in M. oryzae pathogenicity. Furthermore, exogenous carbon source(s) but not antioxidant treatment delayed such mitochondrial dynamics/transition during invasive growth. In contrast, carbon starvation induced the breakdown of the mitochondrial network and led to more punctate mitochondria in vitro. Such nutrient-based regulation of organellar dynamics preceded MoAtg24-mediated mitophagy, which was found to be essential for proper biotrophic development and invasive growth in planta. We propose that precise mitochondrial dynamics and mitophagy occur during the transition from biotrophy to necrotrophy and are required for proper induction and establishment of the blast disease in rice.

2.
Int J Mol Sci ; 20(5)2019 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-30857220

RESUMO

Reactive oxygen species (ROS) are involved in many important processes, including the growth, development, and responses to the environments, in rice (Oryza sativa) and Magnaporthe oryzae. Although ROS are known to be critical components in rice⁻M. oryzae interactions, their regulations and pathways have not yet been completely revealed. Recent studies have provided fascinating insights into the intricate physiological redox balance in rice⁻M. oryzae interactions. In M. oryzae, ROS accumulation is required for the appressorium formation and penetration. However, once inside the rice cells, M. oryzae must scavenge the host-derived ROS to spread invasive hyphae. On the other side, ROS play key roles in rice against M. oryzae. It has been known that, upon perception of M. oryzae, rice plants modulate their activities of ROS generating and scavenging enzymes, mainly on NADPH oxidase OsRbohB, by different signaling pathways to accumulate ROS against rice blast. By contrast, the M. oryzae virulent strains are capable of suppressing ROS accumulation and attenuating rice blast resistance by the secretion of effectors, such as AvrPii and AvrPiz-t. These results suggest that ROS generation and scavenging of ROS are tightly controlled by different pathways in both M. oryzae and rice during rice blast. In this review, the most recent advances in the understanding of the regulatory mechanisms of ROS accumulation and signaling during rice⁻M. oryzae interaction are summarized.


Assuntos
Interações Hospedeiro-Patógeno , Magnaporthe/fisiologia , Oryza/microbiologia , Doenças das Plantas/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Resistência à Doença , Magnaporthe/patogenicidade , Oryza/metabolismo
3.
mSystems ; 3(6)2018.
Artigo em Inglês | MEDLINE | ID: mdl-30505942

RESUMO

The rice blast fungus Magnaporthe oryzae poses a great threat to global food security. During its conidiation (asexual spore formation) and appressorium (infecting structure) formation, autophagy is induced, serving glycogen breakdown or programmed cell death function, both essential for M. oryzae pathogenicity. Recently, we identified an M. oryzae histone acetyltransferase (HAT) Gcn5 as a key regulator in phototropic induction of autophagy and asexual spore formation while serving a cellular function other than autophagy induction during M. oryzae infection. To further understand the regulatory mechanism of Gcn5 on M. oryzae pathogenicity, we set out to identify more Gcn5 substrates by comparative acetylome between the wild-type (WT) and GCN5 overexpression (OX) mutant and between OX mutant and GCN5 deletion (knockout [KO]) mutant. Our results showed that Gcn5 regulates autophagy induction and other important aspects of fungal pathogenicity, including energy metabolism, stress response, cell toxicity and death, likely via both epigenetic regulation (histone acetylation) and posttranslational modification (nonhistone protein acetylation). IMPORTANCE Gcn5 is a histone acetyltransferase that was previously shown to regulate phototropic and starvation-induced autophagy in the rice blast fungus Magnaporthe oryzae, likely via modification on autophagy protein Atg7. In this study, we identified more potential substrates of Gcn5-mediated acetylation by quantitative and comparative acetylome analyses. By epifluorescence microscopy and biochemistry experiments, we verified that Gcn5 may regulate autophagy induction at both the epigenetic and posttranslational levels and regulate autophagic degradation of a critical metabolic enzyme pyruvate kinase (Pk) likely via acetylation. Overall, our findings reveal comprehensive posttranslational modification executed by Gcn5, in response to various external stimuli, to synergistically promote cellular differentiation in a fungal pathogen.

4.
New Phytol ; 214(1): 330-342, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27898176

RESUMO

The interaction of Magnaporthe oryzae, the rice blast fungus, and rice begins when M. oryzae establishes contact with the host plant surface. On perception of appropriate surface signals, M. oryzae forms appressoria and initiates host invasion. Pth11, an important G-protein-coupled receptor necessary for appressorium formation in M. oryzae, contains seven transmembrane regions and a CFEM (common in several fungal extracellular membrane proteins) domain with the characteristic eight cysteine residues. We focused on gaining further insight into the role of the CFEM domain in the putative surface sensing/response function of Pth11. Increased/constitutive expression of CFEM resulted in precocious, albeit defective, appressoria formation in wild-type M. oryzae. The Pth11C63A/C65A mutant, probably with disrupted disulfide bonds in the CFEM, showed delayed appressorium formation and reduced virulence. Furthermore, the accumulation of reactive oxygen species (ROS) was found to be altered in the pth11Δ strain. Strikingly, antioxidant treatment induced appressorium formation in pth11Δ. The Gα subunit MagB and the mitogen-activated protein (MAP) kinase Pmk1 were required for the formation of antioxidant-induced appressoria. We conclude that the CFEM domain of Pth11 is required for proper development of the appressoria, appressoria-like structures and pathogenicity. Highly regulated ROS homeostasis is important for Pth11-mediated appressorium formation in M. oryzae.


Assuntos
Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Magnaporthe/metabolismo , Oryza/microbiologia , Doenças das Plantas/microbiologia , Motivos de Aminoácidos , Sequência de Aminoácidos , Antioxidantes/farmacologia , Sequência Conservada , Cisteína , Subunidades alfa de Proteínas de Ligação ao GTP/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Magnaporthe/patogenicidade , Oxirredução , Domínios Proteicos , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Esporos Fúngicos/efeitos dos fármacos , Esporos Fúngicos/crescimento & desenvolvimento , Relação Estrutura-Atividade , Frações Subcelulares/metabolismo
5.
Semin Cell Dev Biol ; 57: 84-92, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27133541

RESUMO

Pathogenic fungi have evolved highly varied and remarkable strategies to invade and infect their plant hosts. Typically, such fungal pathogens utilize highly specialized infection structures, morphologies or cell types produced from conidia or ascospores on the cognate host surfaces to gain entry therein. Such diverse infection strategies require intricate coordination in cell signaling and differentiation in phytopathogenic fungi. Here, we present an overview of our current understanding of cell signaling and infection-associated development that primes host penetration in the top ten plant pathogenic fungi, which utilize specific receptors to sense and respond to different surface cues, such as topographic features, hydrophobicity, hardness, plant lipids, phytohormones, and/or secreted enzymes. Subsequently, diverse signaling components such as G proteins, cyclic AMP/Protein Kinase A and MAP kinases are activated to enable the differentiation of infection structures. Recent studies have also provided fascinating insights into the spatio-temporal dynamics and specialized sequestration and trafficking of signaling moieties required for proper development of infection structures in phytopathogenic fungi. Molecular insight in such infection-related morphogenesis and cell signaling holds promise for identifying novel strategies for intervention of fungal diseases in plants.


Assuntos
Fungos/metabolismo , Plantas/microbiologia , Transdução de Sinais , Modelos Biológicos , Doenças das Plantas/microbiologia , Receptores de Superfície Celular/metabolismo
6.
New Phytol ; 206(4): 1463-75, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25659573

RESUMO

We identified the Magnaporthe oryzae avirulence effector AvrPi9 cognate to rice blast resistance gene Pi9 by comparative genomics of requisite strains derived from a sequential planting method. AvrPi9 encodes a small secreted protein that appears to localize in the biotrophic interfacial complex and is translocated to the host cell during rice infection. AvrPi9 forms a tandem gene array with its paralogue proximal to centromeric region of chromosome 7. AvrPi9 is expressed highly at early stages during initiation of blast disease. Virulent isolate strains contain Mg-SINE within the AvrPi9 coding sequence. Loss of AvrPi9 did not lead to any discernible defects during growth or pathogenesis in M. oryzae. This study reiterates the role of diverse transposable elements as off-switch agents in acquisition of gain-of-virulence in the rice blast fungus. The prevalence of AvrPi9 correlates well with the avirulence pathotype in diverse blast isolates from the Philippines and China, thus supporting the broad-spectrum resistance conferred by Pi9 in different rice growing areas. Our results revealed that Pi9 and Piz-t at the Pi2/9 locus activate race specific resistance by recognizing sequence-unrelated AvrPi9 and AvrPiz-t genes, respectively.


Assuntos
Resistência à Doença/genética , Proteínas Fúngicas/metabolismo , Genes de Plantas , Genômica/métodos , Magnaporthe/patogenicidade , Oryza/imunologia , Oryza/microbiologia , Doenças das Plantas/microbiologia , Alelos , Cromossomos de Plantas/genética , Regulação Fúngica da Expressão Gênica , Teste de Complementação Genética , Genoma Fúngico , Interações Hospedeiro-Patógeno/genética , Magnaporthe/genética , Dados de Sequência Molecular , Mutagênese Insercional/genética , Oryza/citologia , Oryza/crescimento & desenvolvimento , Doenças das Plantas/imunologia , Análise de Sequência de DNA , Elementos Nucleotídeos Curtos e Dispersos/genética , Virulência/genética
7.
J Exp Bot ; 63(14): 5323-35, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22859673

RESUMO

The RecA/RAD51 family of rice (Oryza sativa) consists of at least 13 members. However, the functions of most of these members are unknown. Here the functional characterization of one member of this family, RAD51C, is reported. Knockout (KO) of RAD51C resulted in both female and male sterility in rice. Transferring RAD51C to the RAD51C-KO line restored fertility. Cytological analyses showed that the sterility of RAD51C-KO plants was associated with abnormal early meiotic processes in both megasporocytes and pollen mother cells (PMCs). PMCs had an absence of normal pachytene chromosomes and had abnormal chromosome fragments. The RAD51C-KO line showed no obvious difference from wild-type plants in mitosis in the anther wall cells, which was consistent with the observation that the RAD51C-KO line did not have obviously abnormal morphology during vegetative development. However, the RAD51C-KO line was sensitive to different DNA-damaging agents. These results suggest that RAD51C is essential for reproductive development by regulating meiosis as well as for DNA damage repair in somatic cells.


Assuntos
Genes de Plantas , Oryza/citologia , Oryza/genética , Proteínas de Plantas/genética , Rad51 Recombinase/genética , Agrobacterium/genética , Cromossomos de Plantas/efeitos dos fármacos , Cromossomos de Plantas/metabolismo , Cromossomos de Plantas/efeitos da radiação , Fragmentação do DNA/efeitos dos fármacos , Fragmentação do DNA/efeitos da radiação , Reparo do DNA/efeitos dos fármacos , Reparo do DNA/efeitos da radiação , DNA Bacteriano/genética , Técnicas de Inativação de Genes , Teste de Complementação Genética , Células Germinativas Vegetais/efeitos dos fármacos , Células Germinativas Vegetais/crescimento & desenvolvimento , Células Germinativas Vegetais/efeitos da radiação , Meiose/efeitos dos fármacos , Meiose/efeitos da radiação , Mitose/efeitos dos fármacos , Mitose/efeitos da radiação , Dados de Sequência Molecular , Mutagênicos/farmacologia , Oryza/efeitos dos fármacos , Oryza/crescimento & desenvolvimento , Filogenia , Infertilidade das Plantas , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Pólen/efeitos dos fármacos , Pólen/crescimento & desenvolvimento , Pólen/efeitos da radiação , Rad51 Recombinase/metabolismo , Análise de Sequência de DNA
8.
J Biotechnol ; 159(4): 283-90, 2012 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-21801764

RESUMO

Rice crops are severely damaged by diseases caused by bacterial, fungal, and viral pathogens. Application of host resistance to these pathogens is the most economical and environmentally friendly approach to solve this problem. Quantitative resistance conferred by quantitative trait loci (QTL) is a valuable resource for the improvement of rice disease resistance. Although numerous resistance QTL against rice diseases have been identified, these resources have not been used effectively in rice improvement because the genetic control of quantitative resistance is complex and the genes underlying most of the resistance QTL remain unknown. This review focuses on the latest molecular progress in quantitative disease resistance in rice. This knowledge will be helpful for characterizing more resistance QTL and turning the quantitative resistance into actual resources for rice protection.


Assuntos
Oryza/genética , Doenças das Plantas/genética , Resistência à Doença , Locos de Características Quantitativas
9.
J Exp Bot ; 62(14): 4863-74, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21725029

RESUMO

Although allelic diversity of genes has been shown to contribute to many phenotypic variations associated with different physiological processes in plants, information on allelic diversity of abiotic stress-responsive genes is limited. Here it is shown that the alleles OsWRKY45-1 and OsWRKY45-2 play different roles in abscisic acid (ABA) signalling and salt stress adaptation in rice. The two alleles had different transcriptional responses to ABA and salt stresses. OsWRKY45-1-overexpressing lines showed reduced ABA sensitivity, whereas OsWRKY45-1-knockout lines showed increased ABA sensitivity. OsWRKY45-1 transgenic plants showed no obvious difference from negative controls in response to salt stress. In contrast, OsWRKY45-2-overexpressing lines showed increased ABA sensitivity and reduced salt stress tolerance, and OsWRKY45-2-suppressing lines showed reduced ABA sensitivity and increased salt stress tolerance. OsWRKY45-1 and OsWRKY45-2 transgenic plants showed differential expression of a set of ABA- and abiotic stress-responsive genes, but they showed similar responses to cold and drought stresses. These results suggest that OsWRKY45-1 negatively and OsWRKY45-2 positively regulates ABA signalling and, in addition, OsWRKY45-2 but not OsWRKY45-1 negatively regulates rice response to salt stress. The different roles of the two alleles in ABA signalling and salt stress may be due to their transcriptional mediation of different signalling pathways.


Assuntos
Ácido Abscísico/metabolismo , Oryza/fisiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Transdução de Sinais , Cloreto de Sódio/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Alelos , Temperatura Baixa , Secas , Regulação da Expressão Gênica de Plantas , Oryza/genética , Estresse Fisiológico
10.
Sci China Life Sci ; 53(11): 1263-73, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21046317

RESUMO

Despite the importance of quantitative disease resistance during a plant's life, little is known about the molecular basis of this type of host-pathogen interaction, because most of the genes underlying resistance quantitative trait loci (QTLs) are unknown. To identify genes contributing to resistance QTLs in rice, we analyzed the colocalization of a set of characterized rice defense-responsive genes and resistance QTLs against different pathogens. We also examined the expression patterns of these genes in response to pathogen infection in the parents of the mapping populations, based on the strategy of validation and functional analysis of the QTLs. The results suggest that defense-responsive genes are important resources of resistance QTLs in rice. OsWRKY45-1 is the gene contributing to a major resistance QTL. NRR, OsGH3-1, and OsGLP members on chromosome 8 contribute alone or collectively to different minor resistance QTLs. These genes function in a basal resistance pathway or in major disease resistance gene-mediated race-specific pathways.


Assuntos
Imunidade Inata/genética , Oryza/genética , Locos de Características Quantitativas , Sequência de Bases , Mapeamento Cromossômico/métodos , Expressão Gênica , Interações Hospedeiro-Patógeno , Dados de Sequência Molecular , Oryza/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Análise de Sequência de DNA
11.
Curr Opin Plant Biol ; 13(2): 181-5, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20097118

RESUMO

Although quantitative resistance loci provide partial and durable resistance to a range of pathogen species in different crops, the molecular mechanism of quantitative disease resistance has remained largely unknown. Recent advances in characterization of the genes contributing to quantitative disease resistance and plant-pathogen interactions at the molecular level provide clues to the molecular bases of broad-spectrum resistance and durable resistance. This emerging knowledge will help in identifying genes involved in quantitative broad-spectrum resistance and durable resistance leading to formulation of efficient ways for using these genetic resources for crop improvement. This knowledge is also turning quantitative resistance genes with minor effects into a productive resource for crop protection via biotechnological approaches.


Assuntos
Imunidade Inata/genética , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Locos de Características Quantitativas/genética , Cruzamento , Produtos Agrícolas/genética , Genes de Plantas/genética
12.
Plant Cell Rep ; 28(1): 113-21, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18818927

RESUMO

Tubby-like protein family has been identified in various multicellular organisms, indicating its fundamental functions in the organisms. However, the roles of plant tubby-like proteins are unknown. In this study, we have defined the tubby-like protein gene (OsTLP) family with 14 members in rice. Most of the OsTLPs harbor a tubby domain in their carboxyl terminus and an F-box domain in the amino terminus. The expression of all the OsTLPs was induced on infection of Xanthomonas oryzae pv. oryzae, which causes bacterial blight, one of the most devastating diseases of rice worldwide. The maximal expression levels were observed at 2-8 h after infection for all the genes. Eight of the 14 OsTLPs were also responsive to wounding. All the OsTLPs showed differential expression in different tissues at different developmental stages. However, four pairs of the 14 OsTLPs, with each pair having high sequence similarity and distributing on the similar position of different chromosomes, showed similar expression pattern in different tissues, indicating their direct relationship in evolution. These results suggest that the OsTLP family is involved in host-pathogen interaction and it may be also associated with other physiological and developmental activities.


Assuntos
Família Multigênica , Oryza/genética , Doenças das Plantas/genética , Proteínas de Plantas/metabolismo , Xanthomonas/patogenicidade , Evolução Molecular , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Interações Hospedeiro-Patógeno , Oryza/metabolismo , Oryza/microbiologia , Filogenia , Proteínas de Plantas/genética , RNA de Plantas/genética , Alinhamento de Sequência
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