FAR1 and FAR2 Regulate the Expression of Genes Associated with Lipid Metabolism in the Rice Blast Fungus Magnaporthe oryzae

Abstract

The rice blast fungus Magnaporthe oryzae causes plant disease via specialised infection structures called appressoria. These dome-shaped cells are able to generate enormous internal pressure, which enables penetration of rice tissue by invasive hyphae. Previous studies have shown that mobilisation of lipid bodies and subsequent lipid metabolism are essential pre-requisites for successful appressorium-mediated plant infection, which requires autophagic recycling of the contents of germinated spores and germ tubes to the developing appressorium. Here, we set out to identify putative regulators of lipid metabolism in the rice blast fungus. We report the identification of FAR1 and FAR2, which encode highly conserved members of the Zn2-Cys6 family of transcriptional regulators. We generated Δfar1, Δfar2 and Δfar1Δfar2 double mutants in M. oryzae and show that these deletion mutants are deficient in growth on long chain fatty acids. In addition, Δfar2 mutants are also unable to grow on acetate and short chain fatty acids. FAR1 and FAR2 are necessary for differential expression of genes involved in fatty acid β-oxidation, acetyl-CoA translocation, peroxisomal biogenesis, and the glyoxylate cycle in response to the presence of lipids. Furthermore, FAR2 is necessary for expression of genes associated with acetyl-CoA synthesis. Interestingly, Δfar1, Δfar2 and Δfar1Δfar2 mutants show no observable delay or reduction in lipid body mobilisation during plant infection, suggesting that these transcriptional regulators control lipid substrate utilization by the fungus but not the mobilisation of intracellular lipid reserves during infection-related morphogenesis.

The basic helix–loop–helix transcription factor Crf1 is required for development and pathogenicity of the rice blast fungus by regulating carbohydrate and lipid metabolism

“…CreA, a carbon catabolite repression factor, negatively regulates lipid catabolism by inhibiting the expression of lipid-utilizing genes when glucose is available in P. oryzae (Cao et al, 2016). Far2, a Zn 2 Cys 6 transcription factor, activates the expression of lipidutilizing genes (Bin Yusof et al, 2014). The deletion of CRF1 significantly decreased the expression level of FAR2 and lipid-utilizing genes, but did not alter the expression levels of CCR genes in P. oryzae grown on both glucose and lipids ( Fig.…”

“…Lipid catabolism is repressed in glucose medium via the carbon catabolite repression pathway (CCR) (Fernandez et al, 2012;Cao et al, 2016), and a CCR gene CREC is required for fungal virulence (Matar et al, 2017). Far1 and Far2 are two Zn 2 Cys 6 transcription factors that regulate the expression of genes associated with lipid metabolism (Bin Yusof et al, 2014). The deletion of CRF1 did not affect the expression level of CCR genes (CREA, CREB, CREC and CRED) (Supporting Information Fig.…”

Differentially expressed alternatively spliced genes in skeletal muscle from cancer patients with cachexia

“…FABP4 has been reported to be expressed in skeletal muscle and play a role in fatty acid transport . FAR1 is studied for its role in β oxidation of fatty acids and acetyl‐CoA translocation . Up‐regulation of both these DASGs may potentially lead to accumulation of fat in skeletal muscle.…”

“…51 FAR1 is studied for its role in β oxidation of fatty acids and acetyl-CoA translocation. 52 Up-regulation of both these DASGs may potentially lead to accumulation of fat in skeletal muscle. Evidence also suggests that sphingolipid accumulation contributes to increased fat accumulation in skeletal muscle.…”

Fatty Acid Synthase Beta Dehydratase in the Lipid Biosynthesis Pathway Is Required for Conidiogenesis, Pigmentation and Appressorium Formation in Magnaporthe oryzae S6

“…Lipid is essential for the virulence of Magnaporthe, as the entire plant infection process, from spore germination to development of the penetration hypha, is fueled by storage reserves carried in the spores [ 14 ]. High levels of triacylglycerol lipase and glycerol have been measured in appressoria during turgor pressure [ 9 , 14 ] It has been shown that pressure of up to 8.0 MPa is generated by the appressorium at the point of penetration [ 15 , 16 ]. The glycerol acts as a highly soluble osmolyte, causing rapid influx of water generating hydrostatic turgor pressure [ 10 ].…”