# Biosynthesis of Natural Rubber: Current State and Perspectives
## 3 Omics Analyses Provide New Insights into Natural Rubber Biosynthesis
### Transcriptome Analysis  
Transcriptome analyses of _H. brasiliensis_ laticifers or rubber particles have been investigated for more than 10 years. All of these analyses revealed that the REF/SRPP gene family members were the most abundant components of the latex transcriptome. They could account for 29% of the total ESTs [24]. Different REF/SRPP isoforms were identified and found to have tissue-specific expression patterns, indicating that they play different roles in different tissues. Unexpectedly, CPTs, which is a potential candidate for rubber polymerase, have relatively low abundance in the latex transcriptome, and not all genes in the MVA and MEP pathways could be detected among the highly expressed ESTs [24; 96; 105]. Expression profile analyses of genes involved in rubber biosynthesis exhibit tissue-specific TSSs, implying alternative means of transcriptional regulation besides changes in mRNA abundance [22; 106]. Stress-related genes, such as REF-like proteins (HbRLPs) and ASR-like proteins (HbASRLPs)-encoding genes, also have high expression levels in the latex, which is consistent with the expansion of the stress/resistance-related genes in the genome, supporting the view that the physiological roles of natural rubber biosynthesis may be related with the defense and resistance process [22; 24; 105]. Transcriptome analysis provided new insights into understanding of the molecular mechanisms underlying high yield of different rubber tree clones. [PERSON] et al. performed a comprehensive cDNA-AFLP transcript profiling on the latex of a super-high-yielding rubber tree clone SY107 and its average counterparts [8]. Their results showed that the improved sucrose loading capability, rubber biosynthesis-preferred sugar utilization, enhanced general metabolism and timely stress alleviation, rather than the rubber-biosynthesis pathway genes, are correlated with the super-high-yielding phenotype of SY107 [8]. [PERSON] et al. compared and analyzed two rubber tree varieties (RRIM 600 and RY 7-20-59) systematically, and suggested that the higher natural rubber yield in RY 7-20-59 likely results from increased total IPP supply, more IPP distribution for rubber biosynthesis and upregulation of the genes involved in rubber biosynthesis pathway [107]. The natural rubber biosynthesis regulation related transcription factors and the transcriptomes of ethephon or jasmonates-treated _H. brasiliensis_ cultivars were also investigated. [PERSON] et al. identified the laticifer-specific genes and their promoter regions from _H. brasiliensis_[108]. They found seven common motifs consisting of eight bases exist in the 5\({}^{\prime}\)-upstream regions of these laticifer-specific genes through promoter clone and in silico analysis. They also identified the putative transcription factors including MYB, Zinc Finger, bHLH, bZIP, PHD Finger and NAC Domain-containing family members, which paved the way to discover the regulatory mechanisms of natural rubber metabolism and accelerated our understanding of the gene regulatory network in _H. brasiliensis_ laticifer [108]. [PERSON] et al. identified and characterized the MYB family members in the laticifer cells of _H. brasiliensis_ and revealed that HbIMYB19 and HbIMYB44 could increase the activity of the promoters of _HbFDPS1_, _HbSRPP_, and _HRT1_, which are associated with the biosynthesis of natural rubber [109]. Sequencing and comparison of rubber tree clone CATAS8-79 and PR107 latex at the transcriptome level revealed that the endogenous jasmonates level, carbohydrate transport and metabolism, and _HMGR_ and _HRT_ expression levels are important for latex regeneration while the endogenous ethylene level, cellulose and lignin content of laticifer cell wall, antioxidants and glucanases are important for the duration of latex flow [110; 111]. Transcriptomes analysis of _H.