Abstract
BackgroundSporisorium scitamineum causes the sugarcane smut disease, one of the most serious constraints to global sugarcane production. S. scitamineum possesses a sexual mating system composed of two mating-type loci, a and b locus. We previously identified and deleted the b locus in S. scitamineum, and found that the resultant SsΔMAT-1b mutant was defective in mating and pathogenicity.ResultsTo further understand the function of b-mating locus, we carried out transcriptome analysis by comparing the transcripts of the mutant strain SsΔMAT-1b, from which the SsbE1 and SsbW1 homeodomain transcription factors have previously been deleted, with those from the wild-type MAT-1 strain. Also the transcripts from SsΔMAT-1b X MAT-2 were compared with those from wild-type MAT-1 X MAT-2 mating. A total of 209 genes were up-regulated (p < 0.05) in the SsΔMAT-1b mutant, compared to the wild-type MAT-1 strain, while 148 genes down-regulated (p < 0.05). In the mixture, 120 genes were up-regulated (p < 0.05) in SsΔMAT-1b X MAT-2, which failed to mate, compared to the wild-type MAT-1 X MAT-2 mating, and 271 genes down-regulated (p < 0.05). By comparing the up- and down-regulated genes in these two sets, it was found that 15 up-regulated and 37 down-regulated genes were common in non-mating haploid and mating mixture, which indeed could be genes regulated by b-locus. Furthermore, GO and KEGG enrichment analysis suggested that carbon metabolism pathway and stress response mediated by Hog1 MAPK signaling pathway were altered in the non-mating sets.ConclusionsExperimental validation results indicate that the bE/bW heterodimeric transcriptional factor, encoded by the b-locus, could regulate S. scitamineum sexual mating and/or filamentous growth via modulating glucose metabolism and Hog1-mediating oxidative response.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2691-5) contains supplementary material, which is available to authorized users.
Highlights
Sporisorium scitamineum causes the sugarcane smut disease, one of the most serious constraints to global sugarcane production
Our study identified several potential target genes of b-locus encoding transcriptional factor, that are likely involved in S. scitamineum sexual mating and/or filamentous growth, and further reveals two critical endogenous/environmental cues: nutrient and redox homeostasis, for mating and/or filementous growth in S. scitamineum
Our finding indicates that S. scitamineum b-locus may regulate small molecular transport, vesicular trafficking, biosynthesis, stress-response mediated by MAPK signaling (Hog1), and a cascade of transcriptional network, during mating and/or filamentous growth
Summary
Sporisorium scitamineum causes the sugarcane smut disease, one of the most serious constraints to global sugarcane production. We previously identified and deleted the b locus in S. scitamineum, and found that the resultant SsΔMAT-1b mutant was defective in mating and pathogenicity. We identified and characterized a b-locus homolog in S. scitamineum, and found that it is essential for sexual mating and filamentous growth [14], but the underlying mechanism remained unclear. Given that b-locus encodes a homeodomain transcription complex, comparative transcriptome analysis may provide useful clues to possible b-locus target gene(s) and functional study of such candidate gene(s) may reveal the molecular basis of b-locus regulating S. scitamineum sexual mating and/or filamentous growth. Our study identified several potential target genes of b-locus encoding transcriptional factor, that are likely involved in S. scitamineum sexual mating and/or filamentous growth, and further reveals two critical endogenous/environmental cues: nutrient and redox homeostasis, for mating and/or filementous growth in S. scitamineum
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