Laboratoire Évolution & Diversité Biologique (EDB, UMR 5174), Université Fédérale de Toulouse Midi-Pyrénées, CNRS, IRD, UPS. 118 route de Narbonne, Bat 4R1, CEDEX 9, 31062 Toulouse, France.
PSL Université Paris: EPHE-UPVD-CNRS, USR 3278 CRIOBE, Université de Perpignan, 52 Avenue Paul Alduy, CEDEX 9, 66860 Perpignan, France.
Genes (Basel). 2019 Mar 28;10(4):256. doi: 10.3390/genes10040256.
Genetic and epigenetic variations are commonly known to underlie phenotypic plastic responses to environmental cues. However, the role of epigenetic variation in plastic responses harboring ecological significance in nature remains to be assessed. The shade avoidance response (SAR) of plants is one of the most prevalent examples of phenotypic plasticity. It is a phenotypic syndrome including stem elongation and multiple other traits. Its ecological significance is widely acknowledged, and it can be adaptive in the presence of competition for light. Underlying genes and pathways were identified, but evidence for its epigenetic basis remains scarce. We used a proven and accessible approach at the population level and compared global DNA methylation between plants exposed to regular light and three different magnitudes of shade in seven highly inbred lines of snapdragon plants () grown in a greenhouse. Our results brought evidence of a strong SAR syndrome for which magnitude did not vary between lines. They also brought evidence that its magnitude was not associated with the global DNA methylation percentage for five of the six traits under study. The magnitude of stem elongation was significantly associated with global DNA demethylation. We discuss the limits of this approach and why caution must be taken with such results. In-depth approaches at the DNA sequence level will be necessary to better understand the molecular basis of the SAR syndrome.
遗传和表观遗传变异通常被认为是表型对环境线索产生可塑性反应的基础。然而，在自然界中具有生态意义的可塑性反应中，表观遗传变异的作用仍有待评估。植物的避荫反应 (SAR) 是表型可塑性最常见的例子之一。它是一种表型综合征，包括茎伸长和其他多种特征。它的生态意义是广泛认可的，在争夺阳光的情况下它是适应性的。已经确定了其潜在的基因和途径，但关于其表观遗传基础的证据仍然很少。我们在群体水平上使用了一种经过验证且易于使用的方法，比较了在温室中生长的 7 个高度近交系金鱼草植物中，暴露于常规光照和三种不同遮荫程度下的植物之间的全基因组 DNA 甲基化。我们的结果为强烈的 SAR 综合征提供了证据，而该综合征在不同品系之间的强度没有差异。它们还表明，在研究的六个特征中的五个特征中，其强度与全基因组 DNA 甲基化百分比无关。茎伸长的幅度与全基因组去甲基化显著相关。我们讨论了这种方法的局限性，以及为什么必须对这些结果持谨慎态度。在 DNA 序列水平上进行深入的方法将是必要的，以更好地理解 SAR 综合征的分子基础。
