INFORM January 2024

24 • inform January 2024, Vol. 35 (1)

Major oilseed crops used for food-based applications primarily accumulate triacylglycerols (TAG) made up of five common fatty acids containing 16-18 carbons and 0-3 double bonds. However, over 450 unusual fatty acids are reported to accumulate in the seed oils of certain plant species (https://doi.org/10.1111/tpj.14102). Hydroxy fatty acids (HFA) are one such group of unusual fatty acids with a hydroxyl functional group attached to the principal acyl chain. Seed oils rich in HFA have a range of applications as starting material in the oleo-chemical industry such as pharma ceuticals, cosmetics, plastics, biodegradable polyesters, lubricants, and biofuels. Novel oil biosynthetic pathway for hydroxy fatty acids Prasad Parchuri, Abdul Azeez, and Philip D. Bates

VARIABILITY Several higher plant species accumulate HFA with various numbers of hydroxyl groups, different chain lengths, and degrees of unsatura tion in their seed oils (Figure 1). Mono-hydroxy fatty acid ricinoleic acid (18:1-OH) accumulates in the castor ( Ricinus communis ) seed oil. The HFA lesquerolic acid (20:1-OH), densipolic acid (18:2-OH) and auricolic acid (20:2-OH) can be found to accumulate in the seed oils of the genus Lesquerella ( https://doi.org/10.1007/s00299-015-1736-6). Recently dis covered HFA include nebraskanic acid (24:1-diOH) and wuhanic acid (24:2-diOH) are dihydroxy fatty acids found in the seed oil of Chinese violet cress ( Orychophragmus violaceus ) ( https://doi.org/10.1038/ s41477-018-0225-7).

• Physaria fendleri , a member of the Brassicaceae family is gaining interest in oilseed research as a non-toxic alternative to castor for producing industrially valuable hydroxylated fatty acids. • P. fendleri accumulates the hydroxy fatty acid, lesquerolic acid, in the sn -1 and sn -3 positions of triacylglycerols via a novel oil assembly pathway called triacylglycerol remodeling. • Exploring and implementing TAG remodeling-based bioengineering strategies may be essential for producing designer oils in traditional oilseed crops.

OH

O

OH

Ricinoleic acid (18:1-OH)

OH

O

OH

Densipolic acid (18:2-OH)

OH

O

OH

Lesquerolic acid (20:1-OH)

OH

O

OH

Auricolic acid (20:2-OH)

FIG. 1. Examples of hydroxy fatty acid chemical structures.