背景回顾：Polyploidy is a prominent feature for genome evolution in many animals and all flowering plants. 

提出问题：Plant polyploids often show enhanced fitness in diverse and extreme environments, but the molecular basis for this remains elusive. Soil salinity presents challenges for many plants including agricultural crops.

主要发现：Here we report that salt tolerance is enhanced in tetraploid rice through lower sodium uptake and correlates with epigenetic regulation of jasmonic acid (JA)–related genes. 

结果1-多倍化诱导低甲基化：Polyploidy induces DNA hypomethylation and potentiates genomic loci coexistent with many stress-responsive genes, which are generally associated with proximal transposable elements (TEs). Under salt stress, the stress-responsive genes including those in the JA pathway are more rapidly induced and expressed at higher levels in tetraploid than in diploid rice, which is concurrent with increased jasmonoyl isoleucine (JA-Ile) content and JA signaling to confer stress tolerance. 

结果2-胁迫诱导高甲基化：After stress, elevated expression of stress-responsive genes in tetraploid rice can induce hypermethylation and suppression of the TEs adjacent to stress-responsive genes. These induced responses are reproducible in a recurring round of salt stress and shared between two japonica tetraploid rice lines. 

结论：The data collectively suggest a feedback relationship between polyploidy-induced hypomethylation in rapid and strong stress response and stress-induced hypermethylation to repress proximal TEs and/or TE-associated stress-responsive genes. This feedback regulation may provide a molecular basis for selection to enhance adaptation of polyploid plants and crops during evolution and domestication.

多倍化是许多动物和所有有花植物基因组演化过程中一个突出的特征。植物多倍化通常能够增强植株在多种和极端环境下的适应性，但是具体的分子机制还不清楚。土壤盐分对于许多的作物来说是一个很严峻的挑战。本文中，作者报道了四倍体水稻通过降低对钠离子的吸收来增强自身的耐盐性，该过程与茉莉酸JA相关基因的表观调控有关。多倍化会诱导DNA低甲基化，增强许多胁迫响应基因的表达，这通常与这些基因附近的转座元件（TE）有关。在盐胁迫下，包括JA途径在内的胁迫响应基因会被快速诱导，并且在四倍体中的表达水平高于二倍体水稻，与茉莉酸异亮氨酸（JA-Ile）含量的增强和JA信号的增强一起赋予了四倍体植株的胁迫耐受性。在胁迫之后，四倍体水稻中胁迫相关基因表达水平的增强能够诱导胁迫响应基因附近TE的超甲基化和抑制。这些诱导响应在一轮反复的盐胁迫中是可重复的，并且在两个四倍体粳稻之间是共通的。这些结果表明多倍化诱导的在快速和强烈胁迫响应的低甲基化与胁迫诱导的超甲基化以抑制近端TE和/或TE相关胁迫响应基因之间存在一个反馈调节关联。这种反馈调节为多倍体植物和作物在演化和驯化过程中的选择提供了分子基础。