| Summary: | Encoding a glutathione S-transferase (GST) and conferring resistance to Fusarium head blight (FHB), <i>Fhb7</i> was successfully isolated from the newly assembled <i>Thinopyrum elongatum</i> genome by researchers, with blasting searches revealing that <i>Thinopyrum</i> gained <i>Fhb7</i> through horizontal gene transfer from an endophytic <i>Epichloë</i> species. On the contrary, our molecular evidence reveals that the homologs of <i>Fhb7</i> are distributed commonly in <i>Triticeae</i>. Other than <i>Thinopyrum</i>, the <i>Fhb7</i> homologs were also detected in four other genera, <i>Elymus</i>, <i>Leymus</i>, <i>Roegneria</i> and <i>Pseudoroegneria</i>, respectively. Sequence comparisons revealed that the protein sequences were at least 94% identical across all of the <i>Fhb7</i> homologs in <i>Triticeae</i> plants, which in turn suggested that the horizontal gene transfer of the <i>Fhb7</i> might have occurred before <i>Triticeae</i> differentiation instead of <i>Thinopyrum</i>. The multiple <i>Fhb7</i> homologs detected in some <i>Triticeae</i> accessions and wheat-<i>Thinopyrum</i> derivatives might be attributed to the alloploid nature and gene duplication during evolution. In addition, we discovered that some wheat-<i>Thinopyrum</i> derivatives carrying the <i>Fhb7</i> homologs had a completely different reaction to Fusarium head blight, which made us question the ability of the GST-encoding <i>Fhb7</i> to resist FHB.
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