Tropical plants have adapted to strong solar ultraviolet (UV) radiation. Here we compare molecular responses of two tropical mangroves Avecennia marina and Rhizophora apiculata to high-dose UV-B. Whole-genome bisulfate sequencing indicates that high UV-B induced comparable hyper- or hypo-methylation in three sequence contexts (CG, CHG, and CHH, where H refers to A, T, or C) in A. marina but mainly CHG hypomethylation in R. apiculata. RNA and small RNA sequencing reveals UV-B induced relaxation of transposable element (TE) silencing together with up-regulation of TE-adjacent genes in R. apiculata but not in A. marina. Despite conserved upregulation of flavonoid biosynthesis and downregulation of photosynthesis genes caused by high UV-B, A. marina specifically upregulated ABC transporter and ubiquinone biosynthesis genes that are known to be protective against UV-B-induced damage. Our results point to divergent responses underlying plant UV-B adaptation at both the epigenetic and transcriptional level.

热带植物已经适应了强烈的太阳紫外线（UV）辐射。在这里，我们比较了两种热带红树林Avecennia marina和Rhizophora apiculata对高剂量 UV-B 的分子反应。全基因组硫酸氢盐测序表明，高 UV-B 在A. marina的三个序列背景（CG、CHG 和 CHH，其中 H 指 A、T 或 C）中诱导了相当的高甲基化或低甲基化，但主要是 CHG 低甲基化在R. apiculata中。 RNA 和小 RNA 测序揭示了R. apiculata中 UV-B 诱导的转座元件 (TE) 沉默松弛以及 TE 邻近基因的上调，但在A. marina中则不然。尽管高 UV-B 导致类黄酮生物合成上调和光合作用基因下调，但A. marina特异性上调 ABC 转运蛋白和泛醌生物合成基因，这些基因已知可防止 UV-B 引起的损伤。我们的结果表明植物在表观遗传和转录水平上的 UV-B 适应存在不同的反应。