Transcriptome analysis and GC-MS profiling of key genes in fatty acid synthesis of Zanthoxylum bungeanum seeds

Zanthoxylum bungeanum is an important commercial crop of the Rutaceae family, its peel is used as a condiment and also in traditional Chinese medicine. Seeds are rich in fatty acids but are usually rejected. To investigate the feasibility of using Z. bungeanum seeds to make biodiesel, techniques including GC MS, transcriptome sequencing and RT-qPCR were used to analyse the fatty acids content and gene expression levels in seeds of five developmental stages. The results show that nine fatty acids are produced and that these accumulate during seed development, to reach the highest levels at maturity. At maturity, the levels of elaidic acid and palmitic acid are highest, each accounting for 22 % of the total. These are followed by linoleic acid, linolenic acid, oleic acid and palmitoleic acid, which account for 18, 15, 7 and 12 % of the total, respectively. The contents of saturated and unsaturated fatty acids continued to accumulate during seed development. At maturity, the content of saturated fatty acids was 46.48 mg/g and the content of unsaturated fatty acids was 142.05 mg/g. Using transcriptome sequencing, the expression levels of 20 genes related to fatty-acid synthesis were determined. A fatty acids synthesis pathway model was established based on gene function annotation information. The results of inter-group correlation analysis and RDA analysis show that ENR, ECR and SAD1 play active roles in fatty acids synthesis in Z. bungeanum and were identified as key genes for fatty acids synthesis.