CgOpt1, a putative oligopeptide transporter from Colletotrichum gloeosporioides that is involved in responses to auxin and pathogenicity

<p>Abstract</p> <p>Background</p> <p>The fungus <it>Colletotrichum gloeosporioides </it>f. sp. <it>aeschynomene </it>produces high levels of indole-3-acetic acid (IAA) in axenic cultures and during plant infection. We generated a suppression subtractive hybridization library enriched for IAA-induced genes and identified a clone, which was highly expressed in IAA-containing medium.</p> <p>Results</p> <p>The corresponding gene showed similarity to oligopeptide transporters of the OPT family and was therefore named <it>CgOPT1</it>. Expression of <it>CgOPT1 </it>in mycelia was low, and was enhanced by external application of IAA. <it>cgopt1</it>-silenced mutants produced less spores, had reduced pigmentation, and were less pathogenic to plants than the wild-type strain. IAA enhanced spore formation and caused changes in colony morphology in the wild-type strain, but had no effect on spore formation or colony morphology of the <it>cgopt1</it>-silenced mutants.</p> <p>Conclusion</p> <p>Our results show that IAA induces developmental changes in <it>C. gloeosporioides</it>. These changes are blocked in <it>cgopt1</it>-silenced mutants, suggesting that this protein is involved in regulation of fungal response to IAA. <it>CgOPT1 </it>is also necessary for full virulence, but it is unclear whether this phenotype is related to auxin.</p

New insights into the origin of the B genome of hexaploid wheat: Evolutionary relationships at the SPA genomic region with the S genome of the diploid relative Aegilops speltoides

<p>Abstract</p> <p>Background</p> <p>Several studies suggested that the diploid ancestor of the B genome of tetraploid and hexaploid wheat species belongs to the <it>Sitopsis </it>section, having <it>Aegilops speltoides </it>(SS, 2n = 14) as the closest identified relative. However molecular relationships based on genomic sequence comparison, including both coding and non-coding DNA, have never been investigated. In an attempt to clarify these relationships, we compared, in this study, sequences of the Storage Protein Activator (SPA) locus region of the S genome of <it>Ae. speltoides </it>(2n = 14) to that of the A, B and D genomes co-resident in the hexaploid wheat species (<it>Triticum aestivum, AABBDD</it>, 2n = 42).</p> <p>Results</p> <p>Four BAC clones, spanning the SPA locus of respectively the A, B, D and S genomes, were isolated and sequenced. Orthologous genomic regions were identified as delimited by shared non-transposable elements and non-coding sequences surrounding the SPA gene and correspond to 35 268, 22 739, 43 397 and 53 919 bp for the A, B, D and S genomes, respectively. Sequence length discrepancies within and outside the SPA orthologous regions are the result of non-shared transposable elements (TE) insertions, all of which inserted after the progenitors of the four genomes divergence.</p> <p>Conclusion</p> <p>On the basis of conserved sequence length as well as identity of the shared non-TE regions and the SPA coding sequence, <it>Ae speltoides </it>appears to be more evolutionary related to the B genome of <it>T. aestivum </it>than the A and D genomes. However, the differential insertions of TEs, none of which are conserved between the two genomes led to the conclusion that the S genome of <it>Ae. speltoides </it>has diverged very early from the progenitor of the B genome which remains to be identified.</p