Genome Biol.科学家破译大麻遗传密码
Genome Biol.：科学家破译大麻遗传密码
2011/10/31 19:30:18
“火人”——每年在美国内华达州举行的一个随心所欲的著名艺术聚会——的参与者们通常都不会注意到新的基因组序列，但他们或许想要看一下在10月出版的《基因组生物学》杂志上的一篇论文。
科学家在论文中报告说，他们已经测定了纤维植物物种大麻（Cannabis sativa）的大部分遗传密码。
研究小组选择的样本是一种名为紫兴都库什的大麻品种。
这一基因组或许能够给研究人员提供新的视点——到底是什么原因让这种盆栽植物在一些民间节庆上如此受欢迎。
通过将紫兴都库什与另一种流行的大麻产品——由大麻纤维生产的菲诺拉（Finola）品种——进行比较，研究小组发现，一种对大量生产赋予了大麻极度快感的化合物质——四氢大麻酚（THC）——前体至关重要的基因被关闭了。
反过来，紫兴都库什大麻只产生少量，甚至不含大麻二酚酸——这是在大麻类植物中发现的一种类似化合物，这或许是因为这些分子吸收了THC所需要的基本成分。
即便是对于那些不吸食大麻的人而言，这也是一条不同寻常的新闻。
大麻是当今世界上最廉价、最普及的毒品。其主要有效化学成分为THC，THC在吸食或口服后有精神和生理的活性作用。人类吸食大麻的历史长达千余年，20世纪在毒品和宗教方面的使用有增加倾向。吸毒者如吸入大剂量大麻，会出现幻觉、妄想和类偏执状态，伴有思维紊乱，自我意识障碍，出现双重人格。
The draft genome and transcriptome of Cannabis sativa
Harm van Bake, Jake M Stout, Atina G Cote, Carling M Tallon, Andrew G Sharpe, Timothy R Hughes and Jonathan E Page
doi: 10.1186/gb-2011-12-10-r102
Background Cannabis sativa has been cultivated throughout human history as a source of fiber, oil and food, and for its medicinal and intoxicating properties. Selective breeding has produced cannabis plants for specific uses, including high-potency marijuana strains and hemp cultivars for fiber and seed production. The molecular biology underlying cannabinoid biosynthesis and other traits of interest is largely unexplored. Results We sequenced genomic DNA and RNA from the marijuana strain Purple Kush using shortread approaches. We report a draft haploid genome sequence of 534 Mb and a transcriptome of 30,000 genes. Comparison of the transcriptomes of Purple Kush and the hemp cultivar Finola revealed that many genes for cannabinoid and precursor pathways are more highly expressed in Purple Kush compared to Finola. The exclusive occurrence of 9-tetrahydrocannabinolic acid synthase in the Purple Kush transcriptome, and its replacement by cannabidiolic acid synthase in Finola, provides an explanation for the production of the psychoactive cannabinoid 9-tetrahydrocannabinol, or THC, in marijuana but not hemp. Resequencing Finola and the hemp cultivar USO-31 showed little difference in gene copy numbers of cannabinoid pathway enzymes. However, single nucleotide variant analysis uncovered a relatively high level of variation between cannabis types, and supported a separation of marijuana and hemp. Conclusions The Cannabis sativa genome enables the analysis of a multifunctional plant that occupies a unique role in human culture. Its availability will further the development of therapeutic marijuana strains with tailored cannabinoid profiles and provide a basis for the breeding of hemp with improved agronomic characteristics.