Department of Plant Breeding and Biotechnology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
J Exp Bot. 2010 Jun;61(11):3089-99. doi: 10.1093/jxb/erq141. Epub 2010 May 23.
Since the cereal endosperm is a dead tissue in the mature grain, beta-oxidation is not possible there. This raises the question about the use of the endosperm oil in cereal grains during germination. In this study, mobilization of lipids in different tissues of germinating oat grains was analysed using thin-layer and gas chromatography. The data imply that the oat endosperm oil [triacylglycerol (TAG)] is not a dead-end product as it was absorbed by the scutellum, either as free fatty acids (FFAs) released from TAG or as intact TAG immediately degraded to FFAs. These data were supported by light and transmission electron microscopy (LM and TEM) studies where close contact between endosperm lipid droplets and the scutellum was observed. The appearance of the fused oil in the oat endosperm changed into oil droplets during germination in areas close to the aleurone and the scutellar epithelium. However, according to the data obtained by TEM these oil droplets are unlikely to be oil bodies surrounded by oleosins. Accumulation of FFA pools in the embryo suggested further transport of FFAs from the scutellum. Noticeably high levels of TAG were also accumulated in the embryo but were not synthesized by re-esterification from imported FFAs. Comparison between two oat cultivars with different amounts of oil and starch in the endosperm suggests that an increased oil to starch ratio in oat grains does not significantly impact the germination process.
由于谷物胚乳在成熟的谷物中是一种死亡组织，β-氧化在那里是不可能的。这就提出了在谷物发芽过程中胚乳油的利用问题。在这项研究中，使用薄层和气相色谱法分析了发芽燕麦粒不同组织中的脂质动员。这些数据表明，燕麦胚乳油[三酰基甘油（TAG）]并不是一种无出路的产物，因为它被盾片吸收，无论是从 TAG 释放的游离脂肪酸（FFA）还是立即降解为 FFA 的完整 TAG。这些数据得到了光和透射电子显微镜（LM 和 TEM）研究的支持，在这些研究中观察到胚乳脂滴与盾片之间的紧密接触。在萌发过程中，靠近糊粉层和盾状上皮的燕麦胚乳中融合的油外观变成了油滴。然而，根据 TEM 获得的数据，这些油滴不太可能是被油体蛋白包围的油体。胚中 FFA 池的积累表明，FFA 进一步从盾片运输。值得注意的是，胚中还积累了大量的 FFA，但不是通过从进口的 FFA 重新酯化合成的。对两种含有不同数量胚乳油和淀粉的燕麦品种的比较表明，燕麦籽粒中油与淀粉的比例增加并不会显著影响发芽过程。
