## 2 Results  
### RNA-Seq Library Construction and Analysis  
Yunma No.1' is the first industrial hemp cultivar bred by the Yunnan Academy of Agricultural Sciences. Its THCA content is <0.3%, complying with the internationally adopted EU standards for hemp [43]. To obtain transcriptomic information of 'Yunma No.1', a strand-specific RNA-Seq library was constructed and sequenced by 90 bp paired-end (PE) sequencing. After filtering the low-quality reads, in total, \(\sim\)66 million clean reads were obtained. More than 83% of them could be mapped to the published _C. sativa_ 'Purple Kush' genome using tophat with the default parameter [44]. Then, the 735,445,652 mapped reads were used for assembly by Cufflinks software [45]. To predict the gene functions,the 67,035 assembly transcripts were annotated by NCBI nonredundant protein sequences (NR) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases [46; 47]. Structural and Transporter Genes Related to the Biosynthetic Pathway of Cannabinoids, FA and Cellulose  
The genes related to cannabinoids, FA and cellulose metabolism were focused on because the main products of C. _sativa_ are derived from cannabinoids, FA and cellulose [3; 4; 5]. Based on the NR annotation, a total of 154 transcripts involved in the biosynthesis of cannabinoids, via the hexanoate, MEP and GPP pathways, were obtained. In the hexanoate pathway, the Delta12-oleic acid desaturase gene was identified [48], which contains one transcript; the Lipoxygenase (LOX) gene contains eight transcripts, and the Acyl-activating enzyme (AAE) gene contains 87 transcripts. In MEP pathway, 1-deoxy-d-xylulose-5-phosphate synthase (DXS), 1-deoxy-d-xylulose-5-phosphate reductio isomerase (DXR), 2-C-methyl-d-erythnitol 4-phosphate ctidylyltransferase (MCT), 4-diphosphocytidyl-2-C-methyl-d-erythnitol kinase (CMK), 2-C-methyl-d-erythnitol 2,4-cyclodiphosphate synthase (MDS), 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase (HDS) and 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (HDR) genes were identified, which contain 6, 13, 7, 2, 3, 15 and 3 transcripts, respectively. In the GPP pathway, the geranyl diphosphate synthase (GPPS) gene was identified, which contains one transcript. In the cannabi-noid biosynthetic pathway, the AAE gene catalyzed the hexanoate to form hexanoyl-CoA, which provided the olivetol synthase (OLS) forming olivetolic acid with substrate. The OLS gene was identified, containing one transcript. The MEP pathway supplies substrates for GPPS, and the prenyl side-chain originates from the prenyltransferase (PT) gene to form cannabigerolic acid (CBGA) [49]. GPPS and PT genes contained one and eight transcripts, respectively. Finally, THCA and CBDA are separately synthesized through THCA synthase (THCAS) and CBDA synthase (CBDAS) (Table S1, Figure 1). In the FA biosynthetic pathway, firstly, the pyruvate oxidative was decarboxylated by the pyruvate dehydrogenase complex (PDHC) to form acetyl-CoA in the plastid, which was reversely catalyzed by acetyl-CoA carboxylase (ACCase) to produce malonyl-CoA [19]. In this study, 18 transcripts of PAHC and eight transcripts of ACCase were identified. For the malonyl-CoA, ACP transacylase (MCAAT) transferred malonyl-CoA to malonyl-acyl carrier protein (ACP), which gradually converted into saturated FAs by \(\beta\)-ketoacyl-ACP synthase (KAS), \(\beta\)-ketoacyl-ACP reductase (KAR), hydroxyacyl-ACP dehydrase (HAD) and enoyl-ACP reductase (EAR). The KAR gene was identified as containing one transcript. The butyryl-ACP and malonyl-ACP were catalyzed by KAS I and KAS II to form 16-carbon palmitoyl-ACP (C16:0-ACP) and 18-carbon stearoyl-ACP (C18:0-ACP). C18:0-ACP was efficiently catalyzed by stearoyl-ACP desaturase (SAD) to produce C18:1-ACP. Next, oleate desaturase (chloroplast-type) (FAD6) catalyzed C18:1-ACP to form C18:2-ACP, which was finally catalyzed by linoleic desaturase (chloroplast-type) (FAD7/8) to form C18:3-ACP [50; 51]. Both FAD6 and FAD7/8 genes contained one transcript.