Globally, farmers cultivate and maintain crop landraces (i.e., traditional varieties). Landraces contain unique diversity shaped in part by natural and human‐mediated selection and are an indispensable resource for farmers. Since environmental conditions change with elevation, crop landraces grown along elevational gradients have provided ideal locations to explore patterns of local adaptation. To further probe traits underlying this differentiation, transcriptome signatures can help provide a foundation for understanding the ways in which functional genetic diversity may be shaped by environment. In this study, we returned to an elevational gradient in Chiapas, Mexico, to assess transcriptional differentiation of genes underlying UV‐B protection in locally adapted maize landraces from multiple elevations. We collected and planted landraces from three elevational zones (lowland, approximately 600 m; midland, approximately 1,550 m; highland approximately 2,100 m) in a common garden at 1,531 m. Using RNA‐seq data derived from leaf tissue, we performed differential expression analysis between maize from these distinct elevations. Highland and lowland landraces displayed differential expression in phenylpropanoid and flavonoid biosynthesis genes involved in the production of UV‐B protectants and did so at a rate greater than expected based on observed background transcriptional differentiation across the genome. These findings provide evidence for the differentiation of suites of genes involved in complex ecologically relevant pathways. Thus, while neutral evolutionary processes may have played a role in the observed patterns of differentiation, UV‐B may have also acted as a selective pressure to differentiate maize landraces in the region. Studies of the distribution of functional crop genetic diversity across variable landscapes can aid us in understanding the response of diversity to abiotic/biotic change and, ultimately, may facilitate its conservation and utilization.

中文翻译：

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墨西哥恰帕斯州跨越海拔梯度的玉米地方品种中UV-B保护基因的转录分化。

在全球范围内，农民种植和维护农作物地方品种（即传统品种）。地方品种具有独特的多样性，部分是受自然和人为介导的选择影响的，是农民不可缺少的资源。由于环境条件随海拔的变化而变化，沿着海拔梯度生长的农作物地方品种为探索当地适应模式提供了理想的位置。为了进一步探讨这种分化的潜在特征，转录组签名可以帮助为理解功能性遗传多样性受环境影响的方式提供基础。在这项研究中，我们返回了墨西哥恰帕斯州的海拔梯度，以评估来自多个海拔高度的局部适应玉米地方品种中UV-B保护的基础基因的转录分化。我们从三个海拔区域（低地约600 m；中地约1,550 m；高地约2,100 m）收集并种植了地方品种，它们位于1,531 m的公共花园中。使用源自叶组织的RNA-seq数据，我们对这些海拔不同的玉米之间进行了差异表达分析。高地和低地地方种在参与生产UV-B保护剂的苯丙烷和类黄酮生物合成基因中表现出差异表达，并且以高于观察到的整个基因组背景转录差异的预期速度进行表达。这些发现为复杂生态相关途径中涉及的基因组的分化提供了证据。因此，虽然中性进化过程可能在观察到的分化模式中起作用，UV-B可能还充当了区分该地区玉米地方品种的选择性压力。对功能性作物遗传多样性在不同景观中的分布的研究可以帮助我们理解多样性对非生物/生物变化的响应，并最终可以促进其保护和利用。