Centre National de Recherche Appliquée au Développement Rural, BP 1444, 101, Ambatobe, Antananarivo, Madagascar.
Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.
Sci Rep. 2021 Apr 14;11(1):8119. doi: 10.1038/s41598-021-87419-0.
Caffeine is the most consumed alkaloid stimulant in the world. It is synthesized through the activity of three known N-methyltransferase proteins. Here we are reporting on the 422-Mb chromosome-level assembly of the Coffea humblotiana genome, a wild and endangered, naturally caffeine-free, species from the Comoro archipelago. We predicted 32,874 genes and anchored 88.7% of the sequence onto the 11 chromosomes. Comparative analyses with the African Robusta coffee genome (C. canephora) revealed an extensive genome conservation, despite an estimated 11 million years of divergence and a broad diversity of genome sizes within the Coffea genus. In this genome, the absence of caffeine is likely due to the absence of the caffeine synthase gene which converts theobromine into caffeine through an illegitimate recombination mechanism. These findings pave the way for further characterization of caffeine-free species in the Coffea genus and will guide research towards naturally-decaffeinated coffee drinks for consumers.
咖啡因是世界上使用最广泛的生物碱类兴奋剂。它是通过三种已知的 N-甲基转移酶蛋白的活性合成的。在这里，我们报道了科摩罗群岛野生濒危、天然不含咖啡因的咖啡品种矮牵牛咖啡的 422Mb 染色体水平基因组组装。我们预测了 32874 个基因，并将 88.7%的序列锚定在 11 条染色体上。与非洲罗布斯塔咖啡基因组（C. canephora）的比较分析表明，尽管估计有 1100 万年的分化和咖啡属内广泛的基因组大小多样性，但基因组仍具有广泛的保守性。在这个基因组中，咖啡因的缺失可能是由于缺乏咖啡因合成酶基因，该基因通过非法重组机制将可可碱转化为咖啡因。这些发现为进一步研究咖啡属中的无咖啡因物种铺平了道路，并将引导研究方向朝着为消费者提供天然脱咖啡因咖啡饮料。
