College of Life Science, Huazhong University of Science and Technology, Wuhan 430074, China.
College of Life Sciences, Jilin University, Changchun 130012, China; Key Laboratory of Pu-erh Tea Science, Ministry of Education, Yunnan Agricultural University, Kunming 650201, China.
Mol Plant. 2016 Jul 6;9(7):1066-77. doi: 10.1016/j.molp.2016.04.016. Epub 2016 May 10.
Maca (Lepidium meyenii Walp, 2n = 8x = 64), belonging to the Brassicaceae family, is an economic plant cultivated in the central Andes sierra in Peru (4000-4500 m). Considering that the rapid uplift of the central Andes occurred 5-10 million years ago (Ma), an evolutionary question arises regarding how plants such as maca acquire high-altitude adaptation within a short geological period. Here, we report the high-quality genome assembly of maca, in which two closely spaced maca-specific whole-genome duplications (WGDs; ∼6.7 Ma) were identified. Comparative genomic analysis between maca and closely related Brassicaceae species revealed expansions of maca genes and gene families involved in abiotic stress response, hormone signaling pathway, and secondary metabolite biosynthesis via WGDs. The retention and subsequent functional divergence of many duplicated genes may account for the morphological and physiological changes (i.e., small leaf shape and self-fertility) in maca in a high-altitude environment. In addition, some duplicated maca genes were identified with functions in morphological adaptation (i.e., LEAF CURLING RESPONSIVENESS) and abiotic stress response (i.e., GLYCINE-RICH RNA-BINDING PROTEINS and DNA-DAMAGE-REPAIR/TOLERATION 2) under positive selection. Collectively, the maca genome provides useful information to understand the important roles of WGDs in the high-altitude adaptation of plants in the Andes.
玛咖（Lepidium meyenii Walp，2n=8x=64），属于十字花科，是一种经济作物，在秘鲁安第斯山脉中海拔 4000-4500 米的高原上种植。考虑到安第斯山脉的快速隆起发生在 500 万至 1000 万年前，就出现了一个进化问题，即像玛咖这样的植物如何在短时间的地质时期内获得适应高海拔的能力。在这里，我们报告了玛咖的高质量基因组组装，其中鉴定出了两个紧密间隔的玛咖特异性全基因组加倍（WGD；约 670 万年前）。对玛咖和相关的十字花科物种的比较基因组分析表明，WGD 导致了与非生物胁迫反应、激素信号通路和次生代谢物生物合成相关的玛咖基因和基因家族的扩张。许多复制基因的保留和随后的功能分化可能导致玛咖在高海拔环境中出现形态和生理变化（即小叶形状和自育性）。此外，一些复制的玛咖基因被鉴定出具有形态适应（即叶片卷曲响应）和非生物胁迫反应（即甘氨酸丰富的 RNA 结合蛋白和 DNA 损伤修复/耐受 2）的功能，这些功能受到正选择的影响。总的来说，玛咖基因组提供了有用的信息，有助于理解 WGD 在安第斯山脉植物的高海拔适应中的重要作用。
