# Molecular Genetic Research and Genetic Engineering of _Taraxaxacum kok-saghyz_ [PERSON]
## 5 TKS transcriptomic and Proteomic Studies  
Hundreds of genes are simultaneously involved in all biological processes in plants, so the most effective way to identify them and to simultaneously evaluate their functions is the sequencing and analysis of transcriptomes. Comparative transcriptomic studies of TKS lines with different accumulations of NR will help elucidate which genes are involved in the synthesis, regulation, and accumulation of this natural polymer and can help turn TKS into an economically viable rubber crop through genetic engineering manipulations. One of the first TKS root transcriptomes was sequenced by the Illumina method and 55,532 transcripts over 200 bp were obtained and 21,036 SNPs were identified [17]. Of these, 50 SNPs were found in 39 transcripts with high homology to 49 genes associated with rubber biosynthesis. The DNA markers discovered during this study became the basis for further work on the genotyping of this plant. A 454 pyrosequencing method was also used to sequence the TKS root transcriptome [46]. In this study 73,350 UniGenes were identified, of which 50,383 were annotated. Subsequent differential gene expression analysis between HR and LR lines revealed a large number of genes, including those involved in rubber biosynthesis. A recent study by [PERSON] et al. [31] aimed to identify DEGs in HR and LR rubber TKS lines. The authors used the nanopore sequencing method in their study, which made it possible to identify a much larger number of expressed genes in TKS roots than in previous studies. As a result, 3134 DEGs were identified. Among these genes, 1157 DEGs were upregulated and 1977 DEGs were downregulated in HR lines compared with LR lines. The HR lines showed mainly genes involved in rubber biosynthesis, while the LR lines had activated genes involved in the synthesis of squalene, phenylpropanoids, fatty acids, and ketones, which require the same substrates (IPP or acetyl-CoA) as biosynthesis of rubber. As for the rubber biosynthesis genes, the lines with a high content of rubber showed an increased content of transcripts of the _CPT1_ and _CPTL1_ genes, while the activities of the _CPT2_, 3, 6, 7, 8, and _CPTL2_ genes were low in both TKS lines [31]. Indeed, the knockdown of _TKCPTL1_, which is predominantly expressed in latex, led to the abolition of rubber synthesis. On the contrary, the suppression of _TKCPTL2_ showed no change in the TKS phenotype, which confirms the importance of the _TKCPTL1_ gene for rubber biosynthesis [75]. The highest content was shown for _SRPP_ gene transcripts, of which eight genes were identified in total. Lines with a high content of rubber were characterized by a high level of expression of the _SRPP4_, 5, 6, and 9 genes. The HR lines also showed a higher expression level of the _REF1_ gene compared with the LR line [31]. These results make it possible to plan further work on the activation and suppression of the expression of certain genes by classical genetic engineering and genome editing in order to increase rubber production. Additionally, based on the obtained results, it is possible to plan the selection of high-yielding TKS populations and lines based on the results of real-time RT-PCR of various genes for the biosynthesis of rubber and other metabolites. Of great interest is the study of not only root, but also leaf metabolites of TKS. Some information in this area can be obtained by studying the transcriptome. For example, the TKS transcriptome has been studied after exogenous treatment with ethephon (a precursor of ethylene), which has hormonal activity and can influence both primary and secondary metabolism. As a result of the studies, an increase in the number of ribosomes, an increase in the expression in the genes of glycolysis/glucoseogenesis, the biosynthesis of phenylpropanoids, and the metabolism of linoleic acid, lysine, starch, and sucrose were revealed [76].