FATTY ACID EXPORTER 1 enhances seed oil content in Brassica napus

Abstract

Abstract FATTY ACID EXPORTER 1 (FAX1) is an initial transporter for fatty acid (FA), in charge of transporting FA from the inside of the plastid to the outside. Brassica napus (B. napus) has nineteen members in the FAX family, of which there are six FAX1 homologous genes. Here, we generated the BnaFAX1 CRISPR mutants (BnaA09.FAX1 and BnaC08.FAX1 were both edited) and overexpression (OE) plants of BnaA09.FAX1 in B. napus. The results showed that the FA content was increased by 0.6–0.9% in OE plant leaves, and the seed oil content was increased by 1.4–1.7% in OE lines, compared to WT. Meanwhile, the content of triacylglycerol, diacylglycerol and phosphatidylcholine was significantly increased in OE seeds. Moreover, seedling biomass and plant height of OE plants were increased compared to WT plants. However, the traits above had no significant difference between the mutants and WT. These results suggest that BnaA09.FAX1 plays a role in improving seed oil accumulation and plant growth, while the function of BnaFAX1 may be compensated by other homologous genes of BnaFAX1 and other BnaFAX genes in the mutants.