Transcriptomics and proteomics profiles of Taraxacum kok-saghyz roots revealed different gene and protein members play different roles for natural rubber biosynthesis

The Russian dandelion (Taraxacum kok-saghyz L. Rodin, TKS) is a potential crop for natural rubber production. Our proteomics results have revealed that both methylerythritol (MEP) and mevalonate (MVA) pathways are important for natural rubber biosynthesis (NRB) in TKS roots. In this study, morphological characteristics and rubber content in TKS roots during five development stages were determined and more laticifer cells, rubber particles, and natural rubber were observed in older TKS roots. Combination of transcriptomics and proteomics was further performed to gain an overall realizing of the principle developmental mechanism and metabolic regulation processes in TKS roots and determine the key genes and proteins for NRB. From the detected TKS roots, 34,710 genes and 3695 proteins were positively identified. Among them, 22194 genes and 2145 proteins were differentially expressed during root development, and their correlation coefficients were calculated. GO and KEGG analysis showed that most up-regulated genes and proteins were involved in carbon metabolic process. A total of 102 NRB-related gene and protein members, including 10 cis-isoprene transferases (CPT), 8 small rubber particle proteins (SRPP), 2 rubber elongation factors (REF), as well as one HRT1-REF bridging protein (HRBP), were identified. Our omics data revealed that different family members of genes and proteins play different roles for NRB in TKS roots. Among them, CPT7, SRPP5, SRPP6 and SRPP9 might play more important roles for NRB in TKS roots.