3.4 | Fatty acid related genes under drought stress inPse. libanotica
To the identify candidate genetic regions associated with fatty acids and their derivatives metabolism pathway, we performed 28 d drought stress treatment without irrigation and conducted transcriptome sequencing on each treatment. Every seven days was taken as a treatment 7 d, 14 d, 21 d, 28 d, and each treatment has three biology repeats. In total, 1,007 differentially expressed genes (DEGs) were shared at four treatments (Figure S6). Differential genes were largely expressed at 14 d drought treatment. Gene Ontology (GO) enrichment analysis showed that 1,190 GO terms were assigned to the 2,300 DEGs that responded to drought treatment (Figure S7). KEGG enrichment analysis showed that DEGs were mainly involved in biosynthesis of unsaturated fatty acids, fatty acid metabolism and elongation process (Figure S8). Comparing the DEGs with expansion and contraction genes, 1,576 DEGs (9.25%) were found in the expansion genes, whereas 61 DEGs (29.35%) were found in the contraction genes.
In total, we identified 14 significantly different expression genes including 20 transcripts which directedly participated in fatty acid biosynthesis under drought stress (Figure 3). In fatty acid biosynthesis pathway of Pse. libanotica , the Acc and Fatb were upregulated during 21 day’s water deficit. Except for two transcripts ofKcs5 and a transcript evm.TU.CTG175.54 , other genesKcs1 , Kcs6 , Kcs11 , Kcs12 , and Kcs20were significantly downregulated. Genes catalyzed VCLFAs derivatives in alcohol-forming pathway (Far , Far1 and Far4 ) and alkane-forming pathway (Cer1 , Cer3 /Cytb5 ,Cyp96a15 /Mah1 ) were upregulated apart from one of theFar1 transcript-evm.TU.CTG5611.2 . In summary, onlyKcs5 and evm.TU.CTG175.54 were responsible for VCLFA elongation in Pse. libanotica .