Development of the protonema and bud formation in mosses

Abstract

SUMMARY In the course of their development the protonemata of Funaria hygrometrica produce two different substances which diffuse into the substrate. In the chloronema a thermo‐labile growth‐promoting substance is formed. In the caulonema, after about 10 days, a substance is produced which is thermostable and soluble in amyl alcohol, which can be dialysed, and which functions as a growth inhibitor. Both substances also influence bud formation. This is at an optimum only when there is a certain balance between these two substances. This promotion is fundamentally different from that brought about by treatment with kinetin, because kinetin can function only as an additional factor in promoting bud formation. Very probably it acts as an agent which creates centres of attraction toward which morphogenetic substances are drawn. This assumption is supported by the fact that kinetin cannot be transported and therefore has no ‘after‐effect’. It probably functions only in the caulonema cell it penetrates. It converts every caulonema cell into a ‘reaction cell’.

Biology of Root Formation and Development

“…Various mosses have been grown on agar in Petri dishes (Allsop and Mitra, 1956;Bopp, 1952Bopp, , 1962Bopp, , 1992Duckett, 1994). As could be expected for autotrophic organisms, they require no additions other than salts containing the known essential ions.…”

“…These filaments have been referred to as chloronemata when they are green and presumably photosynthetic, rhizoids when they anchor plants and caulonemata when they are dark in color and spread through the substrate. It is the caulonemata that can form buds which develop into additional green plants (Bopp, 1962(Bopp, , 1992. The same basic filamentous structure can thus differentiate in various ways (Duckett, 1994) which often intergrade or overlap.…”

In vitro micropropagation and long-term conservation of the endangered moss Splachnum ampullaceum

“…This different pattern in the three media containing only nitrate may be attributable to a need for reduced nitrogen for bud production. It has long been known that bud-forming cells compete to obtain resources from other protonema cells (Bopp 1963); if only nitrate is available, this will have to be reduced in the cells of the protonema, and will thus presumably become available to bud-forming cells more slowly and at lower concentrations. Likewise, the protonema cells will have to bear the increased metabolic cost of nitrate reduction and transport.…”

Evolutionary crossroads in developmental biology: Physcomitrella patens

“…Importantly formins, profilin and ADF are essential for moss viability as it is not possible to obtain stably silenced plants (Augustine et al, 2008;Vidali et al, 2007;Vidali et al, 2009c (Ashton et al, 1979b;Cove, 1992;Johri and Desai, 1973). Likewise, cytokinins regulate gametophore initiation and development (Ashton et al, 1979b;Bopp, 1963), while ABA promotes the production of brachycytes and tmema cells, and dessication tolerance (see Glossary, Box 1) (Decker et al, 2006;Khandelwal et al, 2010). The availability of the complete genome sequence of P. patens allows genes homologous to those encoding components of the hormone-signaling pathways of flowering plants to be searched for.…”