Morphological Plasticity of Some Moss Species in Response to Various Environmental Conditions via In vitro Culture

Abstract

Mosses play important roles in both natural and scientific systems. It is necessary therefore to name moss species that play these roles.But moss species undergo hybridization, polyploidization, and morphologically cryptic genetic differentiation which make identification of mosses a big obstacle. In addition, natural phenotypic plasticity is highly recorded in response to adaptation of mosses to heterogeneous environmental conditions. Although morphological limitations between moss species are not sharp, yet morphological species concept is still most commonly utilized. Unclear species circumscriptions and identification difficulties, based on morphological characters of taxa retarded researches in ecology, biodiversity and applied uses of mosses. A solution for these problems may be either via determining stable morphological characters subject to a minimum of environmentally induced plasticity or via recording the range of changes in characters for species under different environmental conditions. Thus, the aim of the thesis was to record the range of morphological plasticity of four species; Bryum argenteum Hedw., Bryum subapiculatum Hampe, Funaria hygrometricaHedw. and Philonotis hastata (Duby) Wijk & Margad., in light of different percentages of soil maximum water holding capacity and/or various nutrient concentrations in media and determining the stable characters, if found. Mosses are affected by changes in their microhabitats however,the correlation between a particular change in a wild habitat and its effect on a moss plant is quite a problem, whichcan be solved by thein vitro cultivation under controlled conditions. In the present work, the first aim was to develop a successful method for cultivating mosses starting from gametophores. After several trials, axenic cultures were obtained without using chemicals in the sterilization of the gametophores butonly washing by sterilized distilled water. It was a successful method, as the obtained survival percentages, ranged from (67%-100%) for B. argenteum and (33%-100%) for both B. subapiculatum and P. hastata. These percentages represent a very high success percentage in the axenic cultivation of gametophytes. The second and main target was to record morphological changes of Bryum argenteum, B. subapiculatum and Funaria hygrometrica and Philonotis hastatain response to controlled changes of soil maximum water holding capacity and/or nutrient concentrations under in vitro cultivation. Generally, plasticity is either morphological and/or physiological but, in this work focus was on morphological plasticity only. Approximately 30 different characters of protonema and gametophores were recorded. The variation of B. argenteumin response to soil water holding capacity was in the branching pattern, while itsvariation was mainly