研究人員在無毒大麻開發(fā)方面取得了新的進展。美國明尼蘇達大學(xué)的一組科學(xué)家成功鑒定出大麻精神活性物質(zhì)四氫大麻酚酸（THCA）生物合成路徑中幾乎所有的相關(guān)基因,。知道了這些基因,，科學(xué)家就可以通過不同的方法使其沉默，例如RNA干繞,。這些研究人員說,，對這些基因進行研究還可能得到新的藥物以治療疼痛和眩暈。
Marks和他的同事在Journal of Experimental Botany報道了他們的結(jié)果,。他們發(fā)現(xiàn)這些基因在大麻花表面絨毛中的表達量很高,，并且鑒定出其中的特異性聚酮合酶基因。在marijuana品種的絨毛中,，THCA的積累量較高,，而hemp品種中的含量很低。
Hemp中THCA的含量在0.3%以下,，而marijuana中THCA的平均含量高達30%,。Hemp曾經(jīng)一度是很流行的作物，它是高強度工業(yè)纖維和營養(yǎng)油的一個重要來源,。但在藥物法規(guī)頒布以后,，由于擔(dān)心有人會利用hemp來掩蓋marijuana，因此禁止了這種作物的種植,。
這些發(fā)現(xiàn)對啤酒業(yè)也具有重要作用,。研究人員稱，大麻植物中的聚酮合酶基因與啤酒花中的基因非常相似,。啤酒花能產(chǎn)生律草酮和黃腐酚,，前者使啤酒產(chǎn)生獨特的苦味，而后者具有多種健康功效?？茖W(xué)家稱,，這兩種物質(zhì)的生物合成路徑與THCA幾乎完全一致。因此,，研究大麻基因有助于理解啤酒花的生化途徑,。（生物谷Bioon.com）
生物谷推薦原始出處：
Journal of Experimental Botany 2009 60(13):3715-3726; doi:10.1093/jxb/erp210
Identification of candidate genes affecting Δ9-tetrahydrocannabinol biosynthesis in Cannabis sativa
M. David Marks1,*, Li Tian2 , Jonathan P. Wenger1, Stephanie N. Omburo1, Wilfredo Soto-Fuentes1, Ji He2, David R. Gang3, George D. Weiblen1 and Richard A. Dixon2
1Department of Plant Biology, University of Minnesota, 1445 Gortner Ave, St Paul, MN 55108, USA
2Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
3Department of Plant Sciences, University of Arizona, Tucson, AZ 85721-0036, USA
RNA isolated from the glands of a Δ9-tetrahydrocannabinolic acid (THCA)-producing strain of Cannabis sativa was used to generate a cDNA library containing over 100 000 expressed sequence tags (ESTs). Sequencing of over 2000 clones from the library resulted in the identification of over 1000 unigenes. Candidate genes for almost every step in the biochemical pathways leading from primary metabolites to THCA were identified. Quantitative PCR analysis suggested that many of the pathway genes are preferentially expressed in the glands. Hexanoyl-CoA, one of the metabolites required for THCA synthesis, could be made via either de novo fatty acids synthesis or via the breakdown of existing lipids. qPCR analysis supported the de novo pathway. Many of the ESTs encode transcription factors and two putative MYB genes were identified that were preferentially expressed in glands. Given the similarity of the Cannabis MYB genes to those in other species with known functions, these Cannabis MYBs may play roles in regulating gland development and THCA synthesis. Three candidates for the polyketide synthase (PKS) gene responsible for the first committed step in the pathway to THCA were characterized in more detail. One of these was identical to a previously reported chalcone synthase (CHS) and was found to have CHS activity. All three could use malonyl-CoA and hexanoyl-CoA as substrates, including the CHS, but reaction conditions were not identified that allowed for the production of olivetolic acid (the proposed product of the PKS activity needed for THCA synthesis). One of the PKS candidates was highly and specifically expressed in glands (relative to whole leaves) and, on the basis of these expression data, it is proposed to be the most likely PKS responsible for olivetolic acid synthesis in Cannabis glands.
