González-Thuillier Irene, Pellny Till K, Tosi Paola, Mitchell Rowan A C, Haslam Richard, Shewry Peter R
Rothamsted Research, Harpenden, Hertfordshire, AL5 2JQ, UK.
School of Agriculture, Policy and Development, University of Reading, Whiteknights Campus, Early Gate, RG6 6AR, UK.
J Cereal Sci. 2021 Mar;98:103167. doi: 10.1016/j.jcs.2021.103167.
A combination of lipidomics, transcriptomics and bioimaging has been used to study triacylglycerol synthesis and deposition in the developing starchy endosperm of wheat. The content of TAG increased between 14 and 34 days after anthesis, from 50 to 115 mg/100 g dry wt and from about 35 to 175 mg/100 g dry wt in two experiments. The major fatty acids were C16 (palmitic C16:0 and palmitoleic C16:1) and C18 (stearic C18:0, oleic C18:1, linoleic C18:2 and linolenic C18:3), with unsaturated fatty acids accounting for about 75-80% of the total throughout development. Linoleic acid (C18:2) was the major component at all stages and the proportion increased during development. Transcript profiling indicated that predominant route to TAG synthesis and oil accumulation is via the Kennedy pathway and diacylglycerol acyltransferase (DGAT) activity. Confocal microscopy of stained tissue sections showed that TAG accumulated in droplets which are associated with protein and concentrated in the starchy endosperm cells below the sub-aleurone cells. Transcripts encoding 16kd oleosins were also expressed, indicating that the oil droplets are in part stabilised by oleosin proteins.
脂质组学、转录组学和生物成像技术相结合，已被用于研究小麦发育中的淀粉胚乳中三酰甘油的合成与沉积。在两个实验中，开花后14至34天期间，三酰甘油（TAG）含量增加，从50毫克/100克干重增加到115毫克/100克干重，以及从约35毫克/100克干重增加到175毫克/100克干重。主要脂肪酸为C16（棕榈酸C16:0和棕榈油酸C16:1）和C18（硬脂酸C18:0、油酸C18:1、亚油酸C18:2和亚麻酸C18:3），在整个发育过程中，不饱和脂肪酸约占总量的75 - 80%。亚油酸（C18:2）在所有阶段都是主要成分，且其比例在发育过程中增加。转录谱分析表明，TAG合成和油脂积累的主要途径是通过肯尼迪途径和二酰甘油酰基转移酶（DGAT）活性。对染色组织切片的共聚焦显微镜观察显示，TAG积累在与蛋白质相关的液滴中，并集中在糊粉层下的淀粉胚乳细胞中。编码16kd油质蛋白的转录本也有表达，表明油滴部分由油质蛋白稳定。
