BackgroundHevea brasiliensis, a member of the Euphorbiaceae family, is the major commercial source of natural rubber (NR). NR is a latex polymer with high elasticity, flexibility, and resilience that has played a critical role in the world economy since 1876.ResultsHere, we report the draft genome sequence of H. brasiliensis. The assembly spans ~1.1 Gb of the estimated 2.15 Gb haploid genome. Overall, ~78% of the genome was identified as repetitive DNA. Gene prediction shows 68,955 gene models, of which 12.7% are unique to Hevea. Most of the key genes associated with rubber biosynthesis, rubberwood formation, disease resistance, and allergenicity have been identified.ConclusionsThe knowledge gained from this genome sequence will aid in the future development of high-yielding clones to keep up with the ever increasing need for natural rubber.

Cetyltrimethylammonium bromide (CTAB) is the preferred detergent in RNA extraction of oil palm tissues. However, the CTAB-based protocol is time-consuming. In this study, a combination of the CTAB-based method and silica-based purification reduced the extraction time from two days to five hours. Quality of total RNA from 27 different tissues of oil palm was shown to have an RNA integrity number (RIN) value of more than seven. The extracted RNA was evaluated by RT-qPCR using three reference oil palm genes (GRAS, CYP2, and SLU7) and three putative mesocarp-specific transcripts annotated as WRKY DNA-binding protein 70 (WRKY-70), metallothionein (MT) and pentatricopeptide repeat (PPR) genes. Tissue-specific expression profiling across complete developmental stages of mesocarp and vegetative tissues was determined in this study. Overall, the RNA extraction protocol described here is rapid, simple and yields good quality RNAs from oil palm tissues.

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Strong demand for palm oil creates a huge challenge for the industry to produce more palm oil on the shrinking cultivable land mass. Genetic manipulation of oil synthesis in the mesocarp tissue of oil palm offers the opportunity to improve yield and quality of palm oil on the limited land resources. However, more than one mesocarp-specific promoters are required to effectively manipulate oil synthesis to avoid epigenetic silencing caused by the sequence homology in their promoter regions. This study was aimed at identifying genes that are specifically expressed in the mesocarp tissue through in silico analysis of transcriptome datasets from different oil palm tissues. From this analysis, transcripts XLOC_10, annotated as pentatricopeptide repeat (PPR) protein was highly expressed in the mesocarp tissue. Gene expression analysis of PPR in 27 tissues of Elaeis guineensis indicated that this putative mesocarp-specific transcript was expressed in mesocarp and female inflorescence tissues only. Cis-acting elements that are present in the promoter region of PPR showed that PPR might be involved in the lipid biosynthesis and flowering regulation network in oil palm.