Structure and functional properties of the orthotropic and the plagiotropic shoots of Climacium dendroides and Polytrichum commune (Bryophyta)

Abstract

The structure, functional properties and productivity of two moss species, Polytrichum commune and Climacium dendroides, forming the plagiotropic rhizomatous shoots were studied in the middle taiga subzone. Mosses accumulated 30-100 g DW / m 2 ; plagiotropic shoots constituted 40-50% of the total biomass. The differences between the orthotropic (assimilating) and the plagiotropic (heterotrophic) shoots of C. dendroides are stronger than those in P. commune. Plagiotropic rhizomatous shoots of C. dendroides differ from its orthotropic assimilating shoots in more cell layers in stem epidermis, thicker inner cortex, low respiration rates (0.1-0.2 mg СО 2 / g DW h), accumulation of oligosaccharides (50% of the total carbohydrates). The differences in these parameters in Polytrichum are not observed or minimal. Relationships of the respiration rate and the water balance of the studied species with their shoot morphology were shown. P. commune is characterized by higher rates of net photosynthesis, higher ratio of net photosynthesis to water evaporation, higher accumulation of dry mass and assimilating surface area as compared to C. dendroides Резюме Изучена структура, функциональные свойства и продуктивность двух видов мхов Polytrichum commune и Climacium dendroides, формирующих плагиотропные побеги и произрастающих в условиях средней тайги. Мхи накапливали 30-100 г сухой массы на м 2 , 40-50% которой составляли плагиотропные побеги. Значительные различия между ортотропными (ассимилирующими) и плагиотропными (гетеротрофными) побегами показаны для C. dendroides. Плагиотропные корневищеподобные побеги C. dendroides характеризуются значительным развитием эпидермиса, утолщением внутренней коры, низкой скоростью дыхания (0.1-0.2 мг СО 2 / г сухой массы ч), накоплением олигосахаридов (50% от суммы углеводов), в отличие от ортотропных ассими-лирующих побегов. Показана связь метаболической активности и водного обмена c формой роста бриофитов. P. commune, характеризующийся ковровой формой роста, имел более высокую фотосинтетическую способность, эффективность использования воды, продуктивность и площадь ассимилирующей поверхности по сравнению с C. dendroides с древовидной формой роста. У растений P. commune выявлена более высокая скорость испарения воды и отношение видимого фотосинтеза к испарению воды.

Relationships among sporophytic and gametophytic traits of 27 subtropical montane moss species

“…For each replicate, three setae with medium lengths were chosen, and transverse sections (with single‐cell layers) were cut by hand with a razor blade at their midpoints and mounted in water to make temporary slides, then photographed using a BX51 light microscope with DP27 camera (Olympus, Toyko, Japan) at 100–400× magnification (Figure 1). The epidermis, cortex, and central strand, analogous to regions in transverse sections of gametophytic stems, were manually delineated based on their different cell morphologies (Crandall‐Stotler and Bartholomew‐Began, 2007; Maslova et al, 2015) to measure the length of the seta (SetaL), the circumference, and the area of the epidermis (EpiA), transport cell (TCA, as the sum of the cortex and central strand), and the total transverse section (TA) using ImageJ software (National Institutes of Health, Bethesda, MD, USA). The values of the samples were averaged to obtain the final data for each replicate for further analysis.…”