Strigolactones (SLs) are a group of plant hormones involved in many aspects of plant development and stress adaptation. Here, we investigated the drought response of a barley (Hordeum vulgare L.) mutant carrying a missense mutation in the gene encoding the SL‐specific receptor HvD14. Our results clearly showed that hvd14.d mutant is hyper‐sensitive to drought stress. This was illustrated by a lower leaf relative water content (RWC), impaired photosynthesis, disorganization of chloroplast structure, altered stomatal density and slower closure of stomata in response to drought in the mutant compared to the wild type parent cultivar Sebastian. Although the content of abscisic acid (ABA) and its derivatives remained unchanged in the mutant, significant differences in expression of genes related to ABA biosynthesis were observed. Moreover, hvd14.d was insensitive to ABA during seed germination. Analysis of Arabidopsis thaliana mutant atd14‐1 also demonstrated that mutation in the SL receptor resulted in increased sensitivity to drought. Our results indicate that the drought‐sensitive phenotype of barley SL mutant might be caused by a disturbed ABA metabolism and/or signalling pathways. These results together uncovered a link between SL signalling and ABA‐dependent drought stress response in barley.

中文翻译：

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大麦strigolactone信号突变体hvd14.d揭示了strigolactones在脱落酸依赖性干旱反应中的作用。

链果内酯（SLs）是一组植物激素，参与植物发育和胁迫适应的许多方面。在这里，我们调查了大麦（Hordeum vulgare L.）突变体的干旱反应，该突变体在编码SL特异性受体HvD14的基因中带有错义突变。我们的结果清楚地表明hvd14.d突变体对干旱胁迫高度敏感。与野生型亲本品种Sebastian相比，该突变体的叶片相对含水量（RWC）较低，光合作用受损，叶绿体结构紊乱，气孔密度改变和气孔关闭对干旱的响应说明了这一点。虽然脱落酸（ABA）及其衍生物的含量在突变体中保持不变，但观察到与ABA生物合成相关的基因表达的显着差异。此外，hvd14.d在种子发芽过程中对ABA不敏感。分析拟南芥突变体atd14-1还证明了SL受体的突变导致对干旱的敏感性增加。我们的结果表明，大麦SL突变体对干旱敏感的表型可能是由ABA代谢和/或信号传导途径紊乱引起的。这些结果共同揭示了大麦中SL信号与ABA依赖性干旱胁迫反应之间的联系。