scholarly journals The Methylcitrate Cycle is Required for Development and Virulence in the Rice Blast Fungus Pyricularia oryzae

2019 ◽  
Vol 32 (9) ◽  
pp. 1148-1161 ◽  
Author(s):  
Yuxin Yan ◽  
Huan Wang ◽  
Siyi Zhu ◽  
Jing Wang ◽  
Xiaohong Liu ◽  
...  

The methylcitrate cycle metabolizes propionyl-CoA, a toxic metabolite, into pyruvate. Pyricularia oryzae (syn. Magnaporthe oryzae) is a phytopathogenic fungus that causes a destructive blast disease in rice and wheat. We characterized the essential roles of the methylcitrate cycle in the development and virulence of P. oryzae using functional genomics. In P. oryzae, the transcript levels of MCS1 and MCL1, which encode a 2-methylcitrate synthase and a 2-methylisocitrate lyase, respectively, were upregulated during appressorium formation and when grown on propionyl-CoA-producing carbon sources. We found that deletion of MCS1 and MCL1 inhibited fungal growth on media containing both glucose and propionate, and media using propionate or propionyl-CoA-producing amino acids (valine, isoleucine, methionine, and threonine) as the sole carbon or nitrogen sources. The Δmcs1 mutant formed sparse aerial hyphae and did not produce conidia on complete medium (CM), while the Δmcl1 mutant showed decreased conidiation. The aerial mycelium of Δmcs1 displayed a lowered NAD+/NADH ratio, reduced nitric oxide content, and downregulated transcription of hydrophobin genes. Δmcl1 showed reduced appressorium turgor, severely delayed plant penetration, and weakened virulence. Addition of acetate recovered the growth of the wild type and Δmcs1 on medium containing both glucose and propionate and recovered the conidiation of both Δmcs1 and Δmcl1 on CM by reducing propionyl-CoA formation. Deletion of MCL1 together with ICL1, an isocitrate lyase gene in the glyoxylate cycle, greatly reduced the mutant’s virulence as compared with the single-gene deletion mutants (Δicl1 and Δmcl1). This experimental evidence provides important information about the role of the methylcitrate cycle in development and virulence of P. oryzae by detoxification of propionyl-CoA and 2-methylisocitrate.

1985 ◽  
Vol 27 (6) ◽  
pp. 697-704 ◽  
Author(s):  
Hei Leung ◽  
Paul H. Williams

Pyricularia oryzae (teleomorph: Magnaporthe grisea) parasitizes a variety of gramineous hosts and causes the rice blast disease worldwide. Through matings among P. oryzae isolates from rice, finger millet, and weeping lovegrass the inheritance of electrophoretic variants of six enzymes, phosphoglucomutase (PGM), phosphoglucose isomerase (PGI), glycerate-2-dehydrogenase (G2DH), malate dehydrogenase-3 (MDH-3), lactate dehydrogenase-1 (LDH-1), and lactate dehydrogenase-3 (LDH-3) was determined. All six variants were under single gene control as determined by tetrad and random spore analysis. However, at Ldh-3 and Mdh-3, there were consistent excesses of variant alleles among ascospore segregants. Preliminary data on the genetic control of hermaphroditism suggested that maleness in two Japanese rice isolates might be due to a single gene mutation. Linkage analyses among the six electrophoretic markers, mating type, and hermaphroditism suggested loose linkage between Pgm and G2dh with a recombination frequencies of 43.0%.Key words: linkage, Magnaporthe grisea, rice blast fungus.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jiaoyu Wang ◽  
Ling Li ◽  
Rongyao Chai ◽  
Zhen Zhang ◽  
Haiping Qiu ◽  
...  

2021 ◽  
Vol 9 (7) ◽  
pp. 1441
Author(s):  
Van Bach Lam ◽  
Thibault Meyer ◽  
Anthony Arguelles Arias ◽  
Marc Ongena ◽  
Feyisara Eyiwumi Oni ◽  
...  

Rice monoculture in acid sulfate soils (ASSs) is affected by a wide range of abiotic and biotic constraints, including rice blast caused by Pyricularia oryzae. To progress towards a more sustainable agriculture, our research aimed to screen the biocontrol potential of indigenous Bacillus spp. against blast disease by triggering induced systemic resistance (ISR) via root application and direct antagonism. Strains belonging to the B. altitudinis and B. velezensis group could protect rice against blast disease by ISR. UPLC–MS and marker gene replacement methods were used to detect cyclic lipopeptide (CLiP) production and construct CLiPs deficient mutants of B. velezensis, respectively. Here we show that the CLiPs fengycin and iturin are both needed to elicit ISR against rice blast in potting soil and ASS conditions. The CLiPs surfactin, iturin and fengycin completely suppressed P. oryzae spore germination resulting in disease severity reduction when co-applied on rice leaves. In vitro microscopic assays revealed that iturin and fengycin inhibited the mycelial growth of the fungus P. oryzae, while surfactin had no effect. The capacity of indigenous Bacillus spp. to reduce rice blast by direct and indirect antagonism in ASS conditions provides an opportunity to explore their usage for rice blast control in the field.


2001 ◽  
Vol 29 (2) ◽  
pp. 283-286 ◽  
Author(s):  
E. L. Rylott ◽  
M. A. Hooks ◽  
I. A. Graham

Molecular genetic approaches in the model plant Arabidopsis thaliana (ColO) are shedding new light on the role and control of the pathways associated with the mobilization of lipid reserves during oilseed germination and post-germinative growth. Numerous independent studies have reported on the expression of individual genes encoding enzymes from the three major pathways: β-oxidation, the glyoxylate cycle and gluconeogenesis. However, a single comprehensive study of representative genes and enzymes from the different pathways in a single plant species has not been done. Here we present results from Arabidopsis that demonstrate the co-ordinate regulation of gene expression and enzyme activities for the acyl-CoA oxidase- and 3-ketoacyl-CoA thiolasemediated steps of β-oxidation, the isocitrate lyase and malate synthase steps of the glyoxylate cycle and the phosphoenolpyruvate carboxykinase step of gluconeogenesis. The mRNA abundance and enzyme activities increase to a peak at stage 2, 48 h after the onset of seed germination, and decline thereafter either to undetectable levels (for malate synthase and isocitrate lyase) or low basal levels (for the genes of β-oxidation and gluconeogenesis). The co-ordinate induction of all these genes at the onset of germination raises the possibility that a global regulatory mechanism operates to induce the expression of genes associated with the mobilization of storage reserves during the heterotrophic growth period.


1997 ◽  
Vol 53 (4) ◽  
pp. 488-490 ◽  
Author(s):  
S. J. Langridge ◽  
P. J. Baker ◽  
J. R. De Lucas ◽  
S. E. Sedelnikova ◽  
G. Turner ◽  
...  

2008 ◽  
Vol 57 (11) ◽  
pp. 1322-1328 ◽  
Author(s):  
Sophit Thirach ◽  
Chester R. Cooper ◽  
Nongnuch Vanittanakom

Penicillium marneffei is an intracellular dimorphic fungus that can cause a fatal disseminated disease in human immunodeficiency virus-infected patients. The factors that affect the pathogenicity of this fungus remain unclear. Here, we report the isolation and characterization of the gpdA cDNA and genomic clones encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in P. marneffei. Phylogenetic analysis of GAPDH amino acid sequences demonstrated the evolutionary relationship of P. marneffei to other fungi, including the intracellular pathogen Ajellomyces capsulatus. To assess the central importance of phagocytic cells in defence against P. marneffei infection, we used Northern blotting to investigate the response of the isocitrate lyase-encoding gene (acuD) and gpdA to nutrient deprivation inside macrophages. The results revealed that after macrophage internalization, the gene involved in the glyoxylate cycle, acuD, showed higher expression levels as early as 2 h from the start of co-incubation, and the differential expression could be observed again at 8 h after infection. In contrast, the expression of gpdA was downregulated in the yeast phase, as well as during macrophage infection after 2, 4 and 8 h of infection. The induction of P. marneffei acuD was shown to be coordinated with the downregulation of the glycolytic gpdA gene, implying that the cytoplasmic environment of macrophages is deficient in glucose and the glyoxylate pathway could be used by this pathogen to allow subsistence on two-carbon compounds within the host cell following its intracellular persistence.


2008 ◽  
Vol 190 (20) ◽  
pp. 6697-6705 ◽  
Author(s):  
William L. Franck ◽  
Woo-Suk Chang ◽  
Jing Qiu ◽  
Masayuki Sugawara ◽  
Michael J. Sadowsky ◽  
...  

ABSTRACT Bradyrhizobium japonicum is a facultative chemoautotroph capable of utilizing hydrogen gas as an electron donor in a respiratory chain terminated by oxygen to provide energy for cellular processes and carbon dioxide assimilation via a reductive pentose phosphate pathway. A transcriptomic analysis of B. japonicum cultured chemoautotrophically identified 1,485 transcripts, representing 17.5% of the genome, as differentially expressed when compared to heterotrophic cultures. Genetic determinants required for hydrogen utilization and carbon fixation, including the uptake hydrogenase system and components of the Calvin-Benson-Bassham cycle, were strongly induced in chemoautotrophically cultured cells. A putative isocitrate lyase (aceA; blr2455) was among the most strongly upregulated genes, suggesting a role for the glyoxylate cycle during chemoautotrophic growth. Addition of arabinose to chemoautotrophic cultures of B. japonicum did not significantly alter transcript profiles. Furthermore, a subset of nitrogen fixation genes was moderately induced during chemoautotrophic growth. In order to specifically address the role of isocitrate lyase and nitrogenase in chemoautotrophic growth, we cultured aceA, nifD, and nifH mutants under chemoautotrophic conditions. Growth of each mutant was similar to that of the wild type, indicating that the glyoxylate bypass and nitrogenase activity are not essential components of chemoautotrophy in B. japonicum.


2021 ◽  
Vol 12 (1) ◽  
pp. 21-28
Author(s):  
Dmitry Nartymov ◽  
Evgeny Kharitonov ◽  
Elena Dubina ◽  
Sergey Garkusha ◽  
Margarita Ruban ◽  
...  

This article presents the results of the development of a methodology for describing the main morphological and cultural traits of the Pyricularia oryzae Cav. strains widespread in the south of Russia. At the same time, the types of traits are identified and listed, which make it possible to unambiguously determine the uniqueness and variety of the pathogen. The relationships and patterns established using cluster and statistical analysis make it possible to identify the conditions for the development of a pathogen that determine its predominant forms. Thus, research shows that leaf forms of P. oryzae strains isolated from rice plants with leaf form of blast disease have an equally directional growth pattern of a colony with a felt structure, and strains isolated from neck-affected plant form often produce a zone of a colony with a clumpy structure. The classification of cultural traits will make it possible to obtain scientifically grounded and comparable data that can be used in the analysis of the interaction of P. oryzae strains with rice plants on various varieties and in various agro-technological conditions in order to improve and rationalize agricultural activities. The study opens up the possibility of using data in breeding, making it possible to identify forms of a pathogen that infect certain varieties.


1976 ◽  
Vol 40 (11) ◽  
pp. 2137-2142 ◽  
Author(s):  
Toshiya HIRAYAMA ◽  
Tadashi SUDO ◽  
Hideo NAGAYAMA ◽  
Kazuo MATSUDA ◽  
Kinjiro TAMARI

1978 ◽  
Vol 24 (2) ◽  
pp. 149-153 ◽  
Author(s):  
T. M. Lakshmi ◽  
Robert B. Helling

Levels of several intermediary metabolites were measured in cells grown in acetate medium in order to test the hypothesis that the glyoxylate cycle is repressed by phosphoenolpyruvate (PEP). Wild-type cells had less PEP than either isocitrate dehydrogenase – deficient cells (which had greater isocitrate lyase activity than the wild type) or isocitrate dehydrogenase – deficient, citrate synthase – deficient cells (which are poorly inducible). Thus induction of the glyoxylate cycle is more complicated than a simple function of PEP concentration. No correlation between enzyme activity and the level of oxaloacetate, pyruvate, or citrate was found either. Citrate was synthesized in citrate synthase – deficient mutants, possibly via citrate lyase.


Sign in / Sign up

Export Citation Format

Share Document