Development, Genetics and Molecular Biology of Mosses

Abstract

The first descriptions of sex chromosomes in plants, of the continuity of chromosomes during the mitotic cycle and of non‐Mendelian inheritance as well as the introduction of UV‐mutagenesis to genetic research are landmarks in biological sciences first achieved by scientists working on bryophytes. Haploidy of the tissue facilitates mutant isolation and many developmental moss mutants have been isolated. Early moss development is triggered by auxin, by cytokinin and by light, mainly acting via phytochrome and a blue‐light receptor. Due to the simplicity of the plants, development can be pinpointed to the differentiation of a single cell and be analysed in living tissue, making mosses ideal candidates for the analysis of development in an integrated approach of cell and molecular biology. Molecular genetic techniques have been applied mainly to Physcomitrella patens (Hedw.) B.S.G., where efficient protocols for transformation of nuclear DNA have been established and several nuclear, chloroplast and mitochondrial genes have been analysed. These studies reveal that Physcomitrella may be an appropriate model to study plant development in molecular terms. Recently, it has been shown that, in this species, nuclear genes can be targeted very efficiently by homologous recombination, now opening the door to reverse genetics for plant biologists.

Diversification of gene function: homologs of the floral regulatorFLO/LFYcontrol the first zygotic cell division in the mossPhyscomitrella patens

“…6J,K), the number of spores was variable and less than that produced by wild-type sporophytes [approx. 5000 (Reski, 1998)], and the spore germination rates were significantly lower than that of the wild type. When all of the spores in the sporangia of the double disruptant lines (PpLFY1-Development 132 (7) Research article …”

Targeted knock‐out of a gene encoding sulfite reductase in the moss Physcomitrella patens affects gametophytic and sporophytic development

“…Cadmium treatments were performed in two independent repetitions with three independent cultures each. The described DSiR1 mutants are deposited in the International Moss Stock Center with the accessions IMSC 40447 (1-6), IMSC 40450 (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17), IMSC 40454 (4-5) and IMSC 40455 (5-15).…”

Comparative analysis of the SBP-box gene families in P. patens and seed plants

“…In contrast to flowering plants where a reversed situation is encountered, the life cycle of mosses is dominated by a haploid and photoautotrophic gametophyte that supports the diploid sporophytic generation (see Reski, 1998;Cove et al, 2006 for review). As most important difference to flowering plant molecular genetic models, P. patens offers the possibility of efficient gene targeting via homologous recombination (reviewed by Schaefer, 2002) as well as the possibility to make double or triple gene knockouts in one step (Hohe and Reski, 2003).…”