# Molecular Genetic Research and Genetic Engineering of _Taraxaxacum kok-saghyz_ [PERSON]
## 2 Molecular Genetic and Genome-Wide Studies
The largest TKS-specific segment was presence-absence variations (PAV), with a size of 101,040 kb on chromosome 1, which contained 18 genes, including three genes encoding puromycin-sensitive aminopeptides necessary for maintaining cell growth and viability, as well as two genes encoding NB-ARC domain-containing disease-resistance proteins. At the same time, a small specific fragment of the _T. mongolicum_ genome did not contain any genes. To compare genes in the pathway associated with rubber biosynthesis, a total of 90 and 76 candidate rubber biosynthesis genes encoding 21 enzymes were identified in the genomes of TKS and _T. mongolicum_, respectively. TKS-specific rubber biosynthesis genes encoding _cis_-premyltransferase (CPT), 4-hydroxy-3-methylbut-2-enyl diphosphate reductase, A-cholesterol acyltransferase, and mevalonate kinase (MVK) have been discovered. A comparison between NR initiation and elongation genes showed that TKS has a greater number of latex-expressed genes, whose products are involved in both the initiation and the elongation of NR chains. For TKS, there are still no widely available SNP platforms for genome-wide association studies' (GWAS) analyses and searches for high-yielding lines, populations, and individuals. However, research in this direction is already underway. For example, in 2017, 21,036 SNPs were identified in the TKS root transcriptome. Of these, 50 SNPs in 39 transcripts were associated with rubber biosynthesis [17]. More rigorous analyses of trait variance, correlation between traits, and heritability of traits associated with rubber yield were also conducted for association with 42 SNP markers found on genes for rubber biosynthetic enzymes [14]. SNP263, SNP375, SNP912, SNP1006, and SNP1245 were significantly associated with rubber concentration, with a \(p\)-value of less than 0.05. Of these, four markers were located in the genes of enzymes of the 2-C-methyl-D-erythnitol-4 phosphate pathway (MEP). In 2021, a total of 524,812 SNPs were found, based on analysis of whole genome sequencing results [42]. These SNPs were used to construct the population structure, genetic diversity, and evolutionary analysis of 58 wild TKS plants collected from four different regions. Recently, [PERSON] et al. [44] created a special TKS population by crossing lines with low and high rubber content and, based on the results of whole genome sequencing of this hybrid population, created a genetic map, including 322,439 SNPs and a number of rubber content QTLs. Such genetic maps are planned to be used in the creation of modern test systems for the marker-assisted selection of TKS. The results of all these studies have laid the foundation for future large-scale QTL mapping and GWAS that will be used in the genomic selection of TKS for high agronomic performance and rubber yield. A large problem remains concerning the selection of accurate molecular markers that would make it possible to distinguish valuable species of rubber-bearing dandelions from weeds. One solution can be the analysis of DNA markers in the chloroplast genome. Moreover, knowledge of the nucleotide sequences of the chloroplast genome makes it possible to restore phylogenetic relationships between different maternal dandelion species. Based on these considerations, [PERSON] et al. [45] sequenced the chloroplast genomes of TKS (151,338 bp), _T. officinal_ (151,299 bp), and _T. brevicomicultatum_ [PERSON]. (TB) (151,282 bp). As expected, TKS was closer to TB than to _T. officinal_. Of the other Asteraceae species, _Lactuca sativa_ L. was the closest to dandelions. The authors rightly believe that the results of their study can be used to differentiate and purify germplasm from weedy species, as well as to study the potential gene flow among Taraxacum species. To do this, it is proposed to use a number of SNP markers found both in the chloroplast and in the nuclear genome that distinguish these three dandelion species.