School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia.
Research Group on Plant Biology under Mediterranean Conditions, Departament de Biologia, Universitat de les Illes Balears - Instituto de Investigaciones Agroambientales y de la Economía del Agua, Palma, Spain.
Nat Plants. 2020 Mar;6(3):273-279. doi: 10.1038/s41477-020-0602-x. Epub 2020 Mar 9.
The evolution of terrestrial plants capable of growing upwards into the dry atmosphere profoundly transformed the Earth. A transition from small, 'non-vascular' bryophytes to arborescent vascular plants during the Devonian period is partially attributed to the evolutionary innovation of an internal vascular system capable of functioning under the substantial water tension associated with vascular water transport. Here, we show that vascular function in one of the most widespread living bryophytes (Polytrichum commune) exhibits strong functional parallels with the vascular systems of higher plants. These parallels include vascular conduits in Polytrichum that resist buckling while transporting water under tension, and leaves capable of regulating transpiration, permitting photosynthetic gas exchange without cavitation inside the vascular system. The advanced vascular function discovered in this tallest bryophyte family contrasts with the highly inefficient water use found in their leaves, emphasizing the importance of stomatal evolution enabling photosynthesis far above the soil surface.
能够向上生长到干燥大气中的陆地植物的进化，从根本上改变了地球。在泥盆纪时期，从体型较小的“非维管束”苔藓植物向树木状维管束植物的转变，部分归因于内部维管束系统的进化创新，该系统能够在与维管水运相关的巨大水张力下运作。在这里，我们表明，最广泛的现存苔藓植物之一（普通金发藓）的维管功能与高等植物的维管系统表现出强烈的功能相似性。这些相似性包括普通金发藓中的维管导管，在张力下运输水时能够抵抗弯曲，以及能够调节蒸腾作用的叶子，使光合作用气体交换在维管系统内不会发生空化。在这个最高的苔藓植物家族中发现的先进的维管功能与它们叶子中低效的水分利用形成鲜明对比，强调了允许光合作用在远离土壤表面的地方进行的气孔进化的重要性。
