Niranjan Aryal and  Chaofu Lu

Front. Plant Sci., 01 November 2018 | https://doi.org/10.3389/fpls.2018.01576

There have been strong interests in producing unusual fatty acids in oilseed crops to provide renewable industrial feedstock. Results are so far largely disappointing since much lower amounts of such fatty acids accumulate in genetically engineered seeds than in their original natural sources. It has been suggested that the flux of unusual fatty acids through phosphatidylcholine (PC) represents a major bottleneck for high accumulation of such fatty acids in triacylglycerol (TAG). We show here that a phospholipase C-like protein (RcPLCL1) from castor bean, which accumulates nearly 90% of the hydroxylated ricinoleic acid in its seed TAG, increases the amount of hydroxy fatty acids (HFAs) when co-expresses with the fatty acid hydroxylase (RcFAH12) in transgenic seed of Camelina sativa. RcPLCL1 shows hydrolyzing activities on both PC and phosphatidylinositol substrates in our in vitro assay conditions. The PC-PLC activity of the RcPLCL1 may have increased the efficiency of HFA-PC to diacylglycerol conversion, which explains our observation of increased HFA contents in TAG concomitant with decreased HFA in the membrane lipid PC during seed development. Consequently, this may also alleviate the potential detrimental effect of HFA on germination of the engineered camelina seeds. Our results provide new knowledge that will help design effective strategies to engineer high levels of HFAs in transgenic oilseeds.

See: https://www.frontiersin.org/articles/10.3389/fpls.2018.01576/full

Figure 2: Fatty acid profiles of camelina transgenic seeds. RcFAH, Camelina expressing RcFAH12 alone; RcPLCL1, Camelina coexpressing RcFAH12 and RcPLCL1. Data are average ± SD from seeds of homozygous T3 lines showing highest HFA contents. Two-tailed Student’s t-test. ^∗P < 0.05; ^∗∗P < 0.01.