Effect of growth environment on the gene expression and lipids related to triacylglycerol biosynthesis in sea buckthorn (Hippophaë rhamnoides) berries

Sea buckthorn (Hippophae rhamnoides) has numerous health properties and an important potential as a functional food. As one important healthy feature, the beneficial effects of sea buckthorn seed and mesocarp oil to humans have been demonstrated in clinical trials. The seed oil is rich in linoleic (18:2n−6) and α-linolenic (18:3n−3) acids, while the berry mesocarp oil is rich in palmitoleic (16:1n−7) and vaccenic acids (18:1n−7), up to 40% and 10%, respectively. We studied the effect of extreme growth conditions to triacylglycerol content and composition and the related gene expression of two Scandinavian sea buckthorn cultivars. The plants were cultivated at two locations that were very different climate-wise (latitudes 60° N and 68° N) and their berry samples of two years were analyzed. The composition of seed oil and mesocarp oil differed between the growth locations. The amount of linoleic acid increased in both oils in the northern extreme climate. Additionally, the two cultivars differed from each other in mesocarp oil composition. Gene expression levels of genes related to triacylglycerol biosynthesis were under transcriptional control during berry development, while adjustment to growth environment was likely to be under post-transcriptional control. Expression of the genes encoding diacylglycerol acyltransferase (DGAT) increased most prominently in seeds towards berry ripening. The study showed that growth conditions have a significant effect on seed oil biosynthesis and composition.