The CCCH-type transcription factor BnZFP1 is a positive regulator to control oleic acid levels through the expression of diacylglycerol O-acyltransferase 1 gene in Brassica napus

Abstract

In China, the high-oleic acid rapeseed has an oil content of ∼42% and oleic acid (18:1) content of ∼80%. Compared to ordinary rapeseed, high-oleic acid rapeseed has higher levels of monounsaturated fatty acids and lower levels of saturated fatty acid and polyunsaturated fatty acids, and thus is of high nutritional and health value. In addition, high-oleic acid rapeseed oil imparts cardiovascular protective effects. Based on these properties, high-oleic acid oil crops have been extensively investigated and cultivated. We previously identified a CCCH-type transcription factor (BnZFP1, GenBank accession number XM_013796508) that is associated with high oleic acid traits from a Brassica napus subtractive hybridization library. In the present study, we overexpressed and silenced the BnZFP1 gene of B. napus. BnZFP1-overexpressing plants exhibited an 18.8% increase in oleic acid levels and a 3.8% increase in oil content. However, BNZFP1-silenced plants showed a 4.5% decrease in oleic acid levels, whereas no significant change in oil content was observed. Microarray and pull-down assays indicated that BnZFP1 has a total of thirty potential target genes. Further analysis and validation of one of the potential target genes, namely, diacylglycerol O-acyltransferases 1 (DGAT1) gene, indicated that it is positively regulated by BnZFP1. We also observed a correlation between elevated DGAT1 gene expression levels and higher oil content and oleic acid levels in rapeseed.