Sokolowska K, Turzanska M, Nilsson M-C
University of Wroclaw, Institute of Experimental Biology, Department of Plant Developmental Biology, Kanonia 6/8, 50-328 Wroclaw, Poland.
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management, SE 901 83 Umeå, Sweden.
Ann Bot. 2017 Nov 10;120(5):805-817. doi: 10.1093/aob/mcx102.
The ubiquitous feather mosses Pleurozium schreberi and Hylocomium splendens form a thick, continuous boundary layer between the soil and the atmosphere, and play important roles in hydrology and nutrient cycling in tundra and boreal ecosystems. The water fluxes among these mosses and environmental factors controlling them are poorly understood. The aim of this study was to investigate whether feather mosses are capable of internal transport and to provide a better understanding of species-specific morphological traits underlying this function. The impacts of environmental conditions on their internal transport rates were also investigated.
Cells involved in water and food conduction in P. schreberi and H. splendens were identified by transmission electron microscopy. Symplasmic and apoplasmic fluorescent tracers were applied to the moss stems to determine the routes of internal short- and long-distance transport and the impact of air humidity on the transport rates.
Symplasmic transport over short distances occurs via food-conducting cells in both mosses. Pleurozium schreberi is also capable of apoplasmic internal long-distance transport via a central strand of hydroids. These are absent in H. splendens. Reduced air humidity significantly increased the internal transport of both species, and the increase was significantly faster for P. schreberi than for H. splendens.
Pleurozium schreberi and Hylocomium splendens are capable of internal transport but the pathway and conductivity differ due to differences in stem anatomy. These results help explain their varying desiccation tolerance and possibly their differing physiology and autecology and, ultimately, their impact on ecosystem functioning.
常见的羽藓（Pleurozium schreberi）和尖叶泥炭藓（Hylocomium splendens）在土壤与大气之间形成了一层厚厚的、连续的边界层，在苔原和北方生态系统的水文和养分循环中发挥着重要作用。人们对这些苔藓之间的水分通量及其控制因素了解甚少。本研究的目的是调查羽藓是否能够进行内部运输，并更好地理解这种功能背后的物种特异性形态特征。同时还研究了环境条件对其内部运输速率的影响。
通过透射电子显微镜鉴定羽藓和尖叶泥炭藓中参与水分和养分传导的细胞。将共质体和质外体荧光示踪剂应用于苔藓茎，以确定内部短距离和长距离运输的途径以及空气湿度对运输速率的影响。
两种苔藓在短距离内均通过养分传导细胞进行共质体运输。羽藓还能够通过一条中央的导水组织束进行质外体内部长距离运输。尖叶泥炭藓中不存在这种结构。空气湿度降低显著增加了两种苔藓的内部运输，且羽藓的运输速率增加明显快于尖叶泥炭藓。
羽藓和尖叶泥炭藓能够进行内部运输，但由于茎结构的差异，运输途径和传导性有所不同。这些结果有助于解释它们不同的耐旱性，以及可能存在的不同生理和个体生态学特征，最终解释它们对生态系统功能的影响。
