Previous studies suggested that holocentric chromosomes may confer a selective advantage under high ionizing or UV-B radiation due to their tolerance of fragmentation, and that the first plant and animal colonizers of land in the Palaeozoic were or may have been holocentric. Holocentric chromosomes could have, therefore, aided terrestrialization of Earth’s biota half a billion years ago, because leaving water meant facing a sharp increase of UV-B. Because we cannot go back in time, the hypothesis needs to be tested with present-day species using an indicator of UV-B stress. We took advantage of the fact that UV-B intensity increases with elevation and tested whether holocentric plants (six species of Cyperaceae and Juncaceae) are less stressed with increasing elevation than monocentric plants (six species of Poaceae). Phylogenetically corrected regression showed that the proxy for UV-B stress (endopolyploidy index from 671 samples measured by flow cytometry) increased with elevation in holocentric and monocentric species, but the increase was more rapid in monocentric species. Although half a billion year elapsed since terrestrialization, holocentric Cyperaceae and Juncaceae still appear less stressed by UV-B than monocentric Poaceae, despite the other counter UV-B adaptations they both have evolved (graminoid morphology, silica bodies).

中文翻译：

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仰角依赖的内多倍体反应表明具有全中心染色体的植物受UV-B的压力较小

先前的研究表明，由于对碎片的耐受性，全中心染色体在高电离或UV-B辐射下可能具有选择优势，并且古生代土地上的第一批动植物定居者是或可能是全中心的。因此，半轴染色体可能在十亿年前帮助了地球生物群的陆地化，因为离开水意味着面临UV-B的急剧增加。由于我们无法回到过去，因此需要使用UV-B胁迫指标对当前物种的假设进行检验。我们利用了UV-B强度随海拔升高而增加的事实，并测试了海拔高度升高的全心植物（莎草科和c科的6种）是否比单心植物（禾本科的6种）受的胁迫更少。系统发育校正的回归表明，UV-B胁迫（通过流式细胞仪测量的671个样品的内多倍体指数）的代表随着全中心和单中心物种的升高而增加，但在单中心物种中，增长更快。尽管从陆域化以来已经过去了十亿年，但尽管它们都进化出了其他抗UV-B适应性（类胶体形态，硅质体），但全中心的莎草科和君子兰对UV-B的胁迫似乎仍然比单中心禾本科的减轻。