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2016年5月23日，橡胶树（rubber tree）基因组在线发表于《Nature Plants》杂志上。论文的共同第一作者兼共同通讯作者为Chaorong Tang（唐朝荣），中国热带农业科学院橡胶研究中心副所长/研究员，位于中国海南省儋州市。论文的作者中除了三个人分别来自马来西亚、法国和美国，其他都来自中国。

橡胶树（Hevea brasiliensis）属于大戟科（Euphorbiaceae），是一种重要的热带经济作物，其树汁是天然橡胶的主要来源。这篇论文报道的橡胶树基因组组装大小为 1.37 Gb，N50 = 1.28 Mb，占估计的橡胶基因组大小（1.47Gb）的 93.8%。研究使用了二代测序技术的 Illumina GA2 和 Hiseq2000 平台，测序数据量为 138 Gb，覆盖深度为 94x，另外还有 55Gb 的长插入片段的数据用于 scaffold 序列的锚定。研究人员从橡胶基因组中预测了 43792 个编码蛋白基因。 橡胶基因组中的重复序列占比为71%，比例较高。这篇论文的亮点在于发现了REF/SRPP（rubber elongation factor/small rubber particle protein）基因家族在橡胶中极大地扩张，似乎对橡胶的生物合成起决定性作用。

另外值得一提的是，橡胶树的基因组序列早在2013年就由马拉西亚的研究人员报道过，论文发表在《BMC Genomics》，只是测序深度较低，只有大约13X，scaffold 的 N50 只有 2972 bp。

论文题目：The rubber tree genome reveals new insights into rubber production and species adaptation

doi:10.1038/nplants.2016.73

论文摘要：

The Para rubber tree (Hevea brasiliensis) is an economically important tropical tree species that produces natural rubber, an essential industrial raw material. Here we present a high-quality genome assembly of this species (1.37 Gb, scaffold N50 = 1.28 Mb) that covers 93.8% of the genome (1.47 Gb) and harbours 43,792 predicted protein-coding genes. A striking expansion of the REF/SRPP (rubber elongation factor/small rubber particle protein) gene family and its divergence into several laticifer-specific isoforms seem crucial for rubber biosynthesis. The REF/SRPP family has isoforms with sizes similar to or larger than SRPP1 (204 amino acids) in 17 other plants examined, but no isoforms with similar sizes to REF1 (138 amino acids), the predominant molecular variant. A pivotal point in Hevea evolution was the emergence of REF1, which is located on the surface of large rubber particles that account for 93% of rubber in the latex (despite constituting only 6% of total rubber particles, large and small). The stringent control of ethylene synthesis under active ethylene signalling and response in laticifers resolves a longstanding mystery of ethylene stimulation in rubber production. Our study, which includes the re-sequencing of five other Hevea cultivars and extensive RNA-seq data, provides a valuable resource for functional genomics and tools for breeding elite Hevea cultivars.

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