Department of Agronomy and Plant Genetics, University of Minnesota, 411 Borlaug Hall, 1991 Buford Circle, St Paul, MN 55108, USA.
J Exp Bot. 2012 Aug;63(13):4731-40. doi: 10.1093/jxb/ers141.
Fusarium head blight (FHB), caused by Fusarium graminearum, is a devastating disease of small grain cereal crops. FHB causes yield reductions and contamination of grain with trichothecene mycotoxins such as deoxynivalenol (DON). DON inhibits protein synthesis in eukaryotic cells and acts as a virulence factor during fungal pathogenesis, therefore resistance to DON is considered an important component of resistance against FHB. One mechanism of resistance to DON is conversion of DON to DON-3-O-glucoside (D3G). Previous studies showed that expression of the UDP-glucosyltransferase genes HvUGT13248 from barley and AtUGt73C5 (DOGT1) from Arabidopsis thaliana conferred DON resistance to yeast. Over-expression of AtUGt73C5 in Arabidopsis led to increased DON resistance of seedlings but also to dwarfing of transgenic plants due to the formation of brassinosteroid-glucosides. The objectives of this study were to develop transgenic Arabidopsis expressing HvUGT13248, to test for phenotypic changes in growth habit, and the response to DON. Transgenic lines that constitutively expressed the epitope-tagged HvUGT13248 protein exhibited increased resistance to DON in a seed germination assay and converted DON to D3G to a higher extent than the untransformed wild-type. By contrast to the over-expression of DOGT1 in Arabidopsis, which conjugated the brassinosteriod castasterone with a glucoside group resulting in a dwarf phenotype, expression of the barley HvUGT13248 gene did not lead to drastic morphological changes. Consistent with this observation, no castasterone-glucoside formation was detectable in yeast expressing the barley HvUGT13248 gene. This barley UGT is therefore a promising candidate for transgenic approaches aiming to increase DON and Fusarium resistance of crop plants without undesired collateral effects.
镰刀菌穗腐病（FHB），由镰刀菌属真菌引起，是一种毁灭性的小谷物作物病害。FHB 会导致产量降低，并使谷物受到脱氧雪腐镰刀菌烯醇（DON）等真菌毒素的污染。DON 会抑制真核细胞中的蛋白质合成，并在真菌发病机制中充当毒力因子，因此对 DON 的抗性被认为是对 FHB 抗性的重要组成部分。对 DON 的一种抗性机制是将 DON 转化为 DON-3-O-葡萄糖苷（D3G）。先前的研究表明，大麦 UDP-葡萄糖基转移酶基因 HvUGT13248 和拟南芥 AtUGt73C5（DOGT1）的表达使酵母对 DON 具有抗性。拟南芥中 AtUGt73C5 的过表达导致幼苗对 DON 的抗性增加，但由于形成了油菜素内酯-葡萄糖苷，转基因植物也出现了矮化。本研究的目的是开发表达 HvUGT13248 的转基因拟南芥，测试生长习性和对 DON 的反应的表型变化。组成型表达融合标签 HvUGT13248 蛋白的转基因系在种子发芽试验中表现出对 DON 的抗性增加，并且与未转化的野生型相比，将 DON 转化为 D3G 的程度更高。与 DOGT1 在拟南芥中的过表达形成对比，后者将油菜素内酯 castasterone 与葡萄糖苷基团缀合导致矮化表型，大麦 HvUGT13248 基因的表达不会导致形态发生的剧烈变化。与这一观察结果一致，在表达大麦 HvUGT13248 基因的酵母中未检测到 castasterone-glucoside 的形成。因此，这种大麦 UGT 是一种有前途的候选基因，可用于转基因方法，旨在提高作物对 DON 和镰刀菌的抗性，而不会产生不良的附带影响。
