Involvement of auxin and a homeodomain-leucine zipper I gene in rhizoid development of the moss<i>Physcomitrella patens</i>

Sakakibara, Keiko; Nishiyama, Tomoaki; Sumikawa, Naomi; Kofuji, Rumiko; Murata, Takashi; Hasebe, Mitsuyasu

doi:10.1242/dev.00644

Cited by 134 publications

(112 citation statements)

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“…Auxin also markedly stimulates the formation of rhizoids in liverworts and mosses (reviewed by Cove and Ashton, 1984). Their development is also auxin-regulated and during differentiation expression of homeodomain-leucine zipper I gene Pphb7 is induced (Sakakibara et al, 2003). As rhizoids and caulonema are similar structures and products of the same differentiation process (Knoop, 1984), there must also be a relationship between starvation stress and caulonema differentiation.…”

Section: Auxin Regulation Of Caulonema and Protonemal Rhizoid Differementioning

confidence: 99%

Hormonal regulation in green plant lineage families

Johri

2008

Physiol Mol Biol Plants

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The patterns of phytohormones distribution, their native function and possible origin of hormonal regulation across the green plant lineages (chlorophytes, charophytes, bryophytes and tracheophytes) are discussed. The five classical phytohormonesauxins, cytokinins, gibberellins (GA), abscisic acid (ABA) and ethylene occur ubiquitously in green plants. They are produced as secondary metabolites by microorganisms. Some of the bacterial species use phytohormones to interact with the plant as a part of their colonization strategy. Phytohormone biosynthetic pathways in plants seem to be of microbial origin and furthermore, the origin of high affinity perception mechanism could have preceded the recruitment of a metabolite as a hormone. The bryophytes represent the earliest land plants which respond to the phytohormones with the exception of gibberellins. The regulation by auxin and ABA may have evolved before the separation of green algal lineage. Auxin enhances rhizoid and caulonemal differentiation while cytokinins enhance shoot bud formation in mosses. Ethylene retards cell division but seems to promote cell elongation. The presence of responses specific to cytokinins and ethylene strongly suggest the origin of their regulation in bryophytes. The hormonal role of GAs could have evolved in some of the ferns where antheridiogens (compounds related to GAs) and GAs themselves regulate the formation of antheridia.During migration of life forms to land, the tolerance to desiccation may have evolved and is now observed in some of the microorganisms, animals and plants. Besides plants, sequences coding for late embryogenesis abundant-like proteins occur in the genomes of other anhydrobiotic species of microorganisms and nematodes. ABA acts as a stress signal and increases rapidly upon desiccation or in response to some of the abiotic stresses in green plants. As the salt stress also increases ABA release in the culture medium of cyanobacterium Trichormus variabilis, the recruitment of ABA in the regulation of stress responses could have been derived from prokaryotes and present at the level of common ancestor of green plants. The overall hormonal action mechanisms in mosses are remarkably similar to that of the higher plants. As plants are thought to be monophyletic in origin, the existence of remarkably similar hormonal mechanisms in the mosses and higher plants, suggests that some of the basic elements of regulation cascade could have also evolved at the level of common ancestor of plants. The networking of various steps in a cascade or the crosstalk between different cascades is variable and reflects the dynamic interaction between a species and its specific environment.

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Section: Auxin Regulation Of Caulonema and Protonemal Rhizoid Differementioning

confidence: 99%

Hormonal regulation in green plant lineage families

Johri

2008

Physiol Mol Biol Plants

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“…The moss Physcomitrella patens has been recognized as a useful model for the study of plant embryogenesis and development (Cove et al, 1997;Sakakibara et al, 2003) for several reasons. First, the exceptionally high efficiency of homologous recombination in P. patens makes it the only land plant in which gene targeting is feasible (Schaefer and Zrÿd, 1997).…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2005

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After fertilization, the zygote undergoes dynamic changes in chromosomal and cytoplasmic organization, and begins the cell cycles that eventually lead to formation of the multicellular embryo. Specific transcription factors that initiate this cascade of events in land plants have not been identified. We have identified two FLO/LFY genes, PpLFY1 and PpLFY2, that regulate the first cell division after formation of the zygote in the moss Physcomitrella patens. The deduced amino acid sequences of the two PpLFY genes are 94.8% identical to each other and show similar expression patterns. While fertilization occurred in the PpLFY disruptants, the development of double disruptant zygotes was arrested at the single-cell stage. When the double disruptants, as the female parent, were crossed with the wild type, as the male parent, normal sporophytes were formed, supporting the notion that the PpLFY genes function after fertilization to regulate the first mitotic cell division in zygotes. The rare sporophytes that formed on the PpLFY double disruptants showed mostly normal organogenesis, but had abnormalities in the pattern of cell division, supporting a role of PpLFY genes in regulating cell division. The FLO/LFY genes in angiosperms are conserved master regulators of floral identity without any obvious effects on cell division. By contrast, our study suggests that FLO/LFY genes have functions throughout sporophyte development in the basal land plant lineages.

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“…However, spatiotemporal regulation of Rhizoids, which function to acquire nutrients and solutes, are composed of filamentous tissue with a rhizoid apical stem cell at the tip [32]. Rhizoids are similar to protonemata but have brown pigments in the cell wall and immature plastids [33].…”

Section: Stem Cells In the Physcomitrella Haploid Generationmentioning

confidence: 99%

“…Rhizoid apical cells initiate from an epidermal cell of a gametophore stem in a process that is hypothesized to be related to auxin distribution [33]. Auxin regulates RSL1 and RSL2 expression in the primordial epidermal cells that give rise to rhizoid apical stem cells and is necessary and sufficient for rhizoid formation [34,35].…”

Section: Stem Cells In the Physcomitrella Haploid Generationmentioning

confidence: 99%

“…LEAFY genes, which function as floral homeotic genes in angiosperms, are indispensable in this process [40,41]. The sporophyte apical stem cell has two cutting faces and successively divides approximately 12 times to form two rows of cells [33] (Figure 2f). A component of the polycomb repression complex 2 (PRC2), CURLY LEAF (CLF), negatively regulates the longevity of the sporophyte apical stem cell [42].…”

Section: Kofuji and Hasebementioning

confidence: 99%

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Eight types of stem cells in the life cycle of the moss Physcomitrella patens

Kofuji

Hasebe

2014

Current Opinion in Plant Biology

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Physcomitrella patens develops at least seven types of simplex meristem in the gametophyte and at least one type in the sporophyte generation and is a good material for regulatory network comparisons. In this review, we summarize recently revealed molecular mechanisms of stem cell initiation and maintenance in the moss. Kofuji and Hasebe 3 Diversity of stem cells in land plantsStem cells have the ability to self-renew and to form differentiated cells, and several types of stem cells are formed during development and growth [1,2]. Since stem cells are the sources of body parts, their appropriate regulation is necessary in order to generate the body plan successfully. The morphological and anatomical organization of stem cells varies among land plants [3] (Table 1), and comparisons of their regulatory systems in different land plant lineages should be useful in deducing the evolution of body plans as well as understanding the commonalities and differences in stem cell regulatory systems. After several days of cultivation, chloronema apical stem cells transform into caulonema apical stem cells that produce caulonema cells [12]. Both chloronemata and caulonemata are filamentous, and together they are referred to as protonemata.Chloronema cells with round, green chloroplasts are adaptive for photosynthesis, whereas caulonema cells, which are characterized by more rapid growth and spindle-shaped, less-green chloroplasts, are adapted for expansion. The transition from a chloronema to a caulonema apical stem cell is enhanced and retarded by glucose and ammonium ion, respectively, supplemented in the medium, suggesting that the stem cell transition is regulated by the carbon/nitrogen ratio [13] via photosynthesis and metabolic genes including hexokinase [14,15]. Phytochrome and cryptochrome signaling pathways inhibit the chloronema-to-caulonema transition [16,17]. Auxin [18] and the basic helix-loop helix transcription factors ROOT HAIR DEFECTIVE SIX-LIKE1 (PpRSL1) and PpRSL2 [19] as well as diterpenes derived from a gibberellin precursor [20] positively regulate the transition, whereas cytokinin is a indispensable factor for shoot stem cell initiation and maintenance in angiosperms [48] with regulation at the upper levels [49,50]. However, loss of class 1 KNOX genes in Physcomitrella does not cause defects in sporophyte stem cell division other than slight changes in the division angle, but instead causes pleiotropic defects in the later stages of development, suggesting that meristem functions of class 1 KNOX genes were acquired Kofuji and Hasebe 8 in the angiosperm lineage after the divergence of the moss lineage [51].After the PRC2-mediated arrest of sporophyte apical stem cell activity, the cells that have already been produced divide to form the three major parts of a sporophyte body: a sporangium that forms spores via meiosis, a seta that serves as a stalk for the sporangium, and a foot that anchors the sporophyte and interacts with the gametophore tissue [39,51]. The seta meristem has higher cell division...

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Involvement of auxin and a homeodomain-leucine zipper I gene in rhizoid development of the mossPhyscomitrella patens

Cited by 134 publications

References 50 publications

Hormonal regulation in green plant lineage families

Hormonal regulation in green plant lineage families

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

Eight types of stem cells in the life cycle of the moss Physcomitrella patens

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