Desiccation tolerance evolved recurrently across diverse plant lineages to enable survival in water limited conditions. Many resurrection plants are polyploid and several groups have hypothesized that polyploidy contributed to the evolution of desiccation tolerance. However, due to the vast phylogenetic distance between resurrection plant lineages, the rarity of desiccation tolerance, and the prevalence of polyploidy in plants, this hypothesis has been difficult to test. Here, we surveyed natural variation in morphological, reproductive, and desiccation tolerance traits across several cytotypes of a single species to test for links between polyploidy and increased resilience. We sampled multiple natural populations of the resurrection grass Microchloa caffra across an environmental gradient ranging from mesic to xeric in South Africa. We describe two distinct ecotypes of M. caffra that occupy different extremes of the environmental gradient and exhibit consistent differences in ploidy, morphological, reproductive, and desiccation tolerance traits in both field and common growth conditions. Interestingly, plants with more polyploid genomes exhibited consistently higher recovery from desiccation, were less reproductive, and larger than plants with smaller genomes and lower ploidy. These data suggest that selective pressures in increasingly xeric sites may play a role in maintaining and increasing desiccation tolerance that are mediated by changes in ploidy.

中文翻译：

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高阶多倍体在草 Microchloa caffra 中表现出增强的干燥耐受性

不同植物谱系反复进化出耐干燥性，以使其能够在缺水条件下生存。许多复活植物是多倍体，并且一些研究小组假设多倍体有助于耐旱性的进化。然而，由于复活植物谱系之间的巨大系统发育距离、耐干燥性的罕见性以及植物中多倍体的普遍存在，这一假设很难得到检验。在这里，我们调查了单个物种的几种细胞型的形态、繁殖和耐干燥性状的自然变异，以测试多倍体和增强的恢复力之间的联系。我们在南非从中湿到干旱的环境梯度中对复活草 Microchloa caffra 的多个自然种群进行了采样。我们描述了两种不同的 M. caffra 生态型，它们占据环境梯度的不同极端，并在田间和常见生长条件下表现出倍性、形态、繁殖和耐干燥性状的一致差异。有趣的是，与基因组较小和倍性较低的植物相比，具有更多多倍体基因组的植物始终表现出较高的干燥恢复能力，繁殖能力较低，且体型较大。这些数据表明，日益干旱的位点中的选择压力可能在维持和增加由倍性变化介导的干燥耐受性方面发挥作用。