The Analysis Of Lipid Synthesis And Gene Expression Changes In Carya Cathayensis Sarg.

Hickory(Carya cathayensis Sarg.) is now the most important woody oil-bearing plant in the southeast of China, which has the prodigious commercial interest and application potential. In order to exploring the lipid synthesis and inter molecular regulation mechanism during the hickory fruit development, the study detect the raw oil content and the oil composition under the analysis of transcriptome data during development stage. The constructing of hickory lipid synthesis network in terms of origin, synthesis and degradation reveal the regulation of gene expression during the whole lipid accumulation process. Furthermore, according to gene expression network explore a series of potential functional genes.The results of study are as follows:1. Testing the oil content and fatty acid components of hickory, indicated that the regulation of the lipid synthesis. The mature hickory fruit contains more than 70% oil of the dry weight and more than 90% unsaturated fatty acids. As a predominant composition of hickory oil, oleic acid, a fatty acid of MUFA, consists of nearly 80% of the total unsaturated fatty acid content in maturation stage. Besides oleic acid, other compositions include a moderate amount of linoleic acid and small concentrations of palmitic, stearic, and linolenic fatty acids, etc..2. A total of 72.85 GB hickory transcriptome data produces approximately 400 million clean reads with total length of 96, 333,747 bp and average length of 1114.57 bp transcripts, including 86,431 transcripts assembled by these reads. The 1206 genes participating de novo fatty acid synthesis and TAG assembly mainly classified into 7 metabolism pathway related to the accumulation of lipid during the seed development. There are 5606 differential expressed genes in both two years with 1642 under Gene Ontology. These genes were focused into the type “Molecular Function”, and lipid metabolism related genes were enriched in “Biological Process”.3. The inherent mechanism of hickory forming high oil content and oleic acid was analyzed from three aspects, the origin, synthesis and degradation, of lipid metabolism. Analyzing the expression level difference of key genes, ACCase, DGAT, PDAT, SAD, FAD2 etc., indicates that every copies belonging to different expression pattern during the developmental process in different years. Meanwhile, amounts of genes in 2013 taking the more high expression level than 2012 which related to the ABA synthesis and high temperature stress during lipid synthesis.4. Constructing the gene co-expression network obtains 884 candidate genes, which exploring 152 potential genes corresponded to the 29 lipid synthesis genes in a high relationship. These genes belong to the sugar synthesis, transporter protein, oil body protein and transcription factor, which large part of them performing the homologous gene in other species with a high expression level. Other potential genes account for 80% of total genes. The results of co-expression offer a fine foundation for the proofing the hickory lipid synthesis mechanism and exploring of new functional genes in next step.