School of BioSciences, University of Melbourne, Parkville, VIC, 3010, Australia.
Mass Spectrometry Facility, St Vincent Institute of Medical Research, Fitzroy, VIC, 3065, Australia.
Sci Rep. 2023 Dec 19;13(1):22560. doi: 10.1038/s41598-023-49981-7.
This study explores the sphingolipid class of oligohexosylceramides (OHCs), a rarely studied group, in barley (Hordeum vulgare L.) through a new lipidomics approach. Profiling identified 45 OHCs in barley (Hordeum vulgare L.), elucidating their fatty acid (FA), long-chain base (LCB) and sugar residue compositions; and was accomplished by monophasic extraction followed by reverse-phased high performance liquid chromatography electrospray ionisation quadrupole-time-of-flight tandem mass spectrometry (HPLC-ESI-QqTOF-MS/MS) employing parallel reaction monitoring (PRM). Results revealed unknown ceramide species and highlighted distinctive FA and LCB compositions when compared to other sphingolipid classes. Structurally, the OHCs featured predominantly trihydroxy LCBs associated with hydroxylated FAs and oligohexosyl residues consisting of two-five glucose units in a linear 1 → 4 linkage. A survey found OHCs in tissues of major cereal crops while noting their absence in conventional dicot model plants. This study found salinity stress had only minor effects on the OHC profile in barley roots, leaving questions about their precise functions in plant biology unanswered.
本研究通过一种新的脂质组学方法探索了寡己糖神经酰胺（OHC）这一脂类家族，该家族在大麦（Hordeum vulgare L.）中研究较少。通过单相提取和反相高效液相色谱电喷雾离子化四极杆飞行时间串联质谱（HPLC-ESI-QqTOF-MS/MS），并采用平行反应监测（PRM），对大麦中的 45 种 OHC 进行了分析，阐明了它们的脂肪酸（FA）、长链碱基（LCB）和糖残基组成。结果表明，与其他鞘脂类相比，这些 OHC 具有未知的神经酰胺种类和独特的 FA 和 LCB 组成。结构上，OHC 以与羟基化 FA 相关的三羟基 LCB 为主，并带有由两个至五个葡萄糖单元组成的线性 1→4 糖苷键的寡己糖残基。研究发现，OHC 存在于主要谷类作物的组织中，但在传统的双子叶模式植物中却不存在。本研究发现盐胁迫对大麦根中 OHC 谱的影响很小，这使得它们在植物生物学中的确切功能仍未得到解答。
