A novel l‐arabinose‐responsive regulator discovered in the rice‐blast fungus Pyricularia oryzae (Magnaporthe oryzae)

Abstract

In this study we identified the l‐arabinose‐responsive regulator of Pyricularia oryzae that regulates l‐arabinose release and catabolism. Previously we identified the Zn2Cys6 transcription factor (TF), AraR, that has this role in the Trichocomaceae family (Eurotiales), but is absent in other fungi. Candidate Zn2Cys6 TF genes were selected according to their transcript profiles on l‐arabinose. Deletion mutants of these genes were screened for their growth phenotype on l‐arabinose. One mutant, named Δara1, was further analyzed. Our analysis demonstrated that Ara1 from P. oryzae is the functional analog of AraR from A. niger, while there is no significant sequence similarity between them.

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

“…D and Supporting Information Table S2), LAD1 and FBP1 were down‐regulated (both 2.9‐fold) in Δ crf1 when cultured in L‐arabinose medium. PRD1 , LAD1 , LXR1 , XKI1 (Battaglia et al ., ), TKL1 (Fernandez et al ., ) and ARA 1 (Klaubauf et al ., ) were down‐regulated 3.6‐, 2.5‐, 2.8‐, 2.4‐, 3.4‐, and 3.3‐fold, respectively, in the appressoria of Δ crf1, based on qPCR analysis ( p < 0.05) (Fig. D).…”

Regulators of plant biomass degradation in ascomycetous fungi

“…Despite having no significant sequence similarity to AraR, ARA1 appears to be the functional analog of AraR, controlling the arabinanolytic system as well as l -arabinose catabolism. A preliminary phylogenetic analysis shows that it is present only in the Sordariomycetes and Leotiomycetes (Additional file 2) and confirms that there is no significant sequence similarity to AraR [102]. This suggests that AraR and ARA1 are an example of parallel evolution in these fungal clades, which appears to be a relatively uncommon phenomenon for regulators in Ascomycetes.…”

“…It is likely that another arabinanolytic transcription factor exists, that controls abf1 and abf3 [100, 101]. Recently, a new arabinose-responsive regulator was described in M. oryzae , that has orthologs only in Sordariomycetes and Leotiomycetes [102] (see “ l -Arabinose-responsive regulators (AraR and ARA1)”).…”

The transcription factor PDR-1 is a multi-functional regulator and key component of pectin deconstruction and catabolism in Neurospora crassa

“…While PDR-1 appears to combine functions of all three recently reported pectinolytic TFs: Ara1 (from M. oryzae ), GaaR (from B. cinerea ), and RhaR (from the Aspergilli ) [29–31], it is likely not the sole TF involved in regulating pectin catabolism in N. crassa . At least three observations support this conclusion: (1) The Δ pdr - 1 strain has a major growth defect on pectin, but is still able to accumulate between 20 and 30% of WT biomass.…”

“…Previous studies, mostly in the highly pectinolytic fungi Aspergillus niger  ( A. niger ) and Botrytis cinerea ( B. cinerea ), have shown that individual sugars liberated from pectin by secreted enzymes, such as d -GalA, l -Ara, l -Rha and d -Gal, or their respective metabolic derivatives have an inducing potential for the corresponding gene products [25–27]. Recently, transcription factors (TFs) that are conserved across fungi and that mediate the response to some of these monosaccharides have been identified: TRC1 and RhaR for l -Rha in Pichia stipitis ( P. stipitis ) and A. niger , respectively [28, 29], GaaR for d -GalA in B. cinerea [30] and Ara1 for l -Ara in Magnaporthe oryzae ( M. oryzae ) [31]. While identified in different fungi, these TFs have in common that they are responsible for regulating a subset of genes involved in the degradation of a particular pectin domain or pectic polysaccharide: HG for GaaR, the RG-I backbone for RhaR, and the arabinan side chains of RG-I (or hemicellulosic arabinan) for Ara1.…”