# Biosynthesis of Natural Rubber: Current State and Perspectives
## 3 Omics Analyses Provide New Insights into Natural Rubber Biosynthesis  
### Genome Analysis  
Omics including genome, transcriptome, and proteome analyses of the rubber-producing plants generated high-throughput data, helping us to get a comprehensive understanding of the natural rubber biosynthesis process. Draft genome assembly of the common high-yielding _H. brasiliensis_ clone RRIM 600 was firstly reported in 2013 [91] (Table 1). Subsequently, genomes of more _H. brasiliensis_ cultivars were sequenced and annotated. The rubber tree is a diploid (2n = 2x = 36) with an established genome of 2.15 Gb [22]. So far, the longest assembly spans 1.55 Gb and a total of 84,440 high-confidence protein-coding genes have been predicted [22] (Table 1). The _H. brasiliensis_ genome showed a striking expansion of gene families involved in natural rubber biosynthesis, revealing this might be the reason why it could produce high levels of latex [22,91,92]. Seven CPTs, 1 CPTL, 9 REFs, 8 SRPPs and multi-copy genes involved in the MVA and MEP pathways and the biosynthesis of oligomeric allylic pyrophosphates were identified and annotated in the _H. brasiliensis_ genome [22,93]. Some of these rubber biosynthesis-related genes are arranged in clusters in the genome, suggesting coordinated evolution and expression for latex production [22]. _H. brasiliensis_ has the highest number of disease resistance-related genes compared with other _Euphorbiaceae_ genomes, indicating that these genes may play import roles in response to stresses and diseases caused by fungal pathogens [22]. Through genome or RNA sequencing, molecular markers such as simple sequence repeats (SSRs) and single nucleotide polymorphisms (SNPs) have been identified, and a high-density genetic linkage map was constructed for _H. brasiliensis_[94, 95, 96, 97, 98, 99, 100, 101, 102]. These data would be a valuable information resource for future genetic analyses such as quantitative trait loci (QTL) identification, linkage disequilibrium investigations and phylogenetic studies and a powerful tool for breeding elite rubber tree cultivars. [PERSON] and colleagues constructed the first specific genome and transcriptome database for _H. brasiliensis_ ([[http://matsui-lab.riken.jp/rubber/](http://matsui-lab.riken.jp/rubber/)]([http://matsui-lab.riken.jp/rubber/](http://matsui-lab.riken.jp/rubber/)), accessed on 20 December 2018), including functional annotations and multi-transcriptome data of RNA-seq, full-length cDNAs, ESTs and genome wide transcription start sites (TSSs) [93]. Gene co-expression network is also presented in the database which provides information for identifying functionally related gene sets and genes regulated by the same transcription factor [93]. This database will accelerate our understanding of the molecular mechanism of natural rubber biosynthesis and assist both industrial and academic utilization of rubber tree and important close industrial relatives. Genomes of other rubber-producing plants were also sequenced and assembled (Table 1). [PERSON] et al. reported a high-quality assembly of \(\sim\)1.2 Gb genome with at least 26,723 predicted genes for _E. ulmoides_[5]. Similar to _H. brasiliensis_, _E. ulmoides_ has gene number expansion for multiple