Glycerolipids, sphingolipids, and sterol lipids constitute the major lipid classes in plants. Sterol lipids are composed of free and conjugated sterols, i.e., sterol esters, sterol glycosides, and acylated sterol glycosides. Sterol lipids play crucial roles during adaption to abiotic stresses and plant-pathogen interactions. Presently, no comprehensive method for sterol lipid quantification in plants is available. We used nanospray ionization quadrupole-time-of-flight mass spectrometry (Q-TOF MS) to resolve and identify the molecular species of all four sterol lipid classes from Arabidopsis thaliana. Free sterols were derivatized with chlorobetainyl chloride. Sterol esters, sterol glycosides, and acylated sterol glycosides were ionized as ammonium adducts. Quantification of molecular species was achieved in the positive mode after fragmentation in the presence of internal standards. The amounts of sterol lipids quantified by Q-TOF MS/MS were validated by comparison with results obtained with TLC/GC. Quantification of sterol lipids from leaves and roots of phosphate-deprived A. thaliana plants revealed changes in the amounts and molecular species composition. The Q-TOF method is far more sensitive than GC or HPLC. Therefore, Q-TOF MS/MS provides a comprehensive strategy for sterol lipid quantification that can be adapted to other tandem mass spectrometers.
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机译:甘油脂,鞘脂和固醇脂构成植物中的主要脂类。甾醇脂质由游离的和缀合的固醇,即固醇酯,固醇糖苷和酰化的固醇糖苷组成。在适应非生物胁迫和植物-病原体相互作用期间,甾醇类脂质起着至关重要的作用。目前,尚无用于植物中固醇脂质定量的综合方法。我们使用纳喷雾电离四极杆飞行时间质谱(Q-TOF MS)来解析和鉴定拟南芥中所有四种固醇脂类的分子种类。游离固醇用氯贝甜酰氯衍生化。固醇酯,固醇糖苷和酰化固醇糖苷被离子化为铵加合物。在存在内标物的情况下,片段化后以阳性模式实现了分子种类的定量。通过与TLC / GC获得的结果进行比较,验证了通过Q-TOF MS / MS定量得到的固醇脂质含量。磷酸盐剥夺的拟南芥植物叶和根中固醇脂质的定量显示了数量和分子种类组成的变化。 Q-TOF方法比GC或HPLC灵敏得多。因此,Q-TOF MS / MS提供了一种适用于其他串联质谱仪的固醇脂质定量的综合策略。
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