Physcomitrella patens

The moss Physcomitrella patens ( Physcomitrella patens )

The moss Physcomitrella patens ( Physcomitrella patens ) is a moss from the family of Funariaceae. It serves as a model organism in the study of evolution, development and physiology of plants.

Features

Axenic in vitro cultivation of Physcomitrella patens

Protonemazellen of the moss Physcomitrella patens

Moss bioreactor with Physcomitrella patens

Four different ecotypes of Physcomitrella patens from the collection of the IMSC

From Physcomitrella wild-type (A) derived phenotypes ( BD).

The plants are up to 5 mm high and in loose flocks. The upper leaves are enlarged, broadly lanceolate and serrated blunt the edge. The midrib ending just below the blade tip. The lamina cells are large and rhombic.

Physcomitrella patens is a moss kleistokarpes. The capsule has no lid, is spherical with a short tip. It is set to a short seta and is enclosed by the leaves.

The species is very short-lived, she will complete her life cycle in just four weeks.

Dissemination and locations

The species occurs in Eurasia and North America. It grows on silty or clayey soils, especially in dried-up river banks and drained ponds. At higher altitudes it is missing.

Development

The haploid Meiospore germinates under the influence of light and water to the filamentous protonema (sometimes also called " pre-seed " or, especially in the old literature, " Confervenfäden " '), which consists primarily of Chloronemazellen. Under the influence of auxin this differentiated Caulonemazellen. Both cell types grown by single-edged crest cells. The protonema is the juvenile form of the gametophyte dar. The taking place under the influence of cytokinin transition to growth by three -edged crest cells, the induction of moss bud, marks the transition to the adult gametophyte, the articulated in stems, leaves and rhizoids moss plants (see also thallus ). Since this terminal the gametangia, carries the female archegonia and male antheridia ( Physcomitrella patens is monoecious ), called this moss plants in the technical term also gametophores. The induction of gametangia occurs in Physcomitrella in short days and low temperatures. Each archegonium contains an egg. The fertilization of the egg by the motile spermatozoids requires a connection of archegonium and antheridium by water, for example, a drop of dew. The archegonium in the developing embryo is the diploid sporophyte (the " moss capsule " ) dar. He lives epiphytic on the Gametophor and is nourished by it. Physcomitrella carries a maximum of a spore capsule per Gametophor, that is from the multiple fertilisable archegonia per Gametophor only one developed into a mature sporophyte. The archegonium in the developing sporophyte tears while growing the archegonium. The Archegonienhals remains loosely attached to the sporophyte - this residue is called a calyptra. Down the sporophyte is a " stalks ", the Seta, connected to the Gametophor. In Physcomitrella patens, the seta is very short and the sporophyte secondarily reduced; he is kleistokarp. This means that the meiospores be formed in the sporophyte by meiosis not leave through a predetermined opening the sporophyte, but that this tear or burst, in order to release the spores.

Model organism

Physcomitrella patens is used as a model organism because it is the only known plant with a very efficient recombination homologs. In this capacity, P. patens is similar to the baker's yeast. This technique of gene targeting a DNA fragment can be integrated at a predetermined site of the genome. The generated knockout - mosses are helpful in elucidating the function of genes. This technique is called reverse genetics. So questions can be solved on the evolution of plants. The genome of P. patens, with around 500 MBp (500 million base pairs), which are organized into 27 chromosomes, has been completely sequenced in 2007. The number of genes was determined to be 34.835.

In addition, P. patens has importance in biotechnology, for example in the production of drugs in a process developed by Reski moss bioreactor.

Different ecotypes, mutants and transgenic strains of P. patens are deposited on the International Moss Stock Center.