Transition to a Land Flora: Phylogenetic Relationships of the Green Algae and Bryophytes

Mishler, Brent D.; Churchill, Steven P.

doi:10.1111/j.1096-0031.1985.tb00431.x

Cited by 215 publications

(139 citation statements)

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“…Early land plants evolved mechanisms to survive harsh drying environments to successfully exploit different ecosystems on land. Therefore, it has been postulated that the initial evolution of vegetative DT, in both vegetative and reproductive stages, was a crucial step required for the colonization of land by primitive plants of a fresh water origin (2).…”

mentioning

confidence: 99%

Regulatory network analysis reveals novel regulators of seed desiccation tolerance in Arabidopsis thaliana

González-Morales

Montes

Hayano-Kanashiro

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

122

100

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Desiccation tolerance (DT) is a remarkable process that allows seeds in the dry state to remain viable for long periods of time that in some instances exceed 1,000 y. It has been postulated that seed DT evolved by rewiring the regulatory and signaling networks that controlled vegetative DT, which itself emerged as a crucial adaptive trait of early land plants. Understanding the networks that regulate seed desiccation tolerance in model plant systems would provide the tools to understand an evolutionary process that played a crucial role in the diversification of flowering plants. In this work, we used an integrated approach that included genomics, bioinformatics, metabolomics, and molecular genetics to identify and validate molecular networks that control the acquisition of DT in Arabidopsis seeds. Two DT-specific transcriptional subnetworks were identified related to storage of reserve compounds and cellular protection mechanisms that act downstream of the embryo development master regulators LEAFY COTYLEDON 1 and 2, FUSCA 3, and ABSCICIC ACID INSENSI-TIVE 3. Among the transcription factors identified as major nodes in the DT regulatory subnetworks, PLATZ1, PLATZ2, and AGL67 were confirmed by knockout mutants and overexpression in a desiccationintolerant mutant background to play an important role in seed DT. Additionally, we found that constitutive expression of PLATZ1 in WT plants confers partial DT in vegetative tissues.regulatory network | desiccation tolerance | drought tolerance | seed development | oligosaccharides D esiccation tolerance (DT) can be operationally defined as the ability of an organism to dry to equilibrium with moderately dry air (50 to 70% relative humidity at 20 to 30°C) and then resume normal function when rehydrated (1). DT organisms orchestrate a complex number of responses to protect cellular structures and prevent damage to proteins and nucleic acids. Early land plants evolved mechanisms to survive harsh drying environments to successfully exploit different ecosystems on land. Therefore, it has been postulated that the initial evolution of vegetative DT, in both vegetative and reproductive stages, was a crucial step required for the colonization of land by primitive plants of a fresh water origin (2).Seed DT, a trait that allows terrestrial plants to survive long periods of sparse water until favorable conditions are present for germination, is probably part of the answer to Darwin's "abominable mystery," the sudden appearance of great angiosperm diversity in the fossil record. In angiosperms, DT is acquired at the seed maturation stage, which involves a complex regulatory network (3, 4) that activates a large subset of genes involved in a number of mechanisms that influence seed survival in the dry state. The set of genes required for seed DT includes genes encoding protective proteins such as late embryogenesis abundant (LEA) (5, 6) and heat shock proteins (HSPs) (7), enzymes involved in scavenging reactive oxygen species (8) and the biosynthesis of protective compounds such as o...

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mentioning

confidence: 99%

Regulatory network analysis reveals novel regulators of seed desiccation tolerance in Arabidopsis thaliana

González-Morales

Montes

Hayano-Kanashiro

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

122

100

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“…These two groups both show up in the fossil record in the late Ordovician-Silurian, ~400-450 Mya, (Mishler & Churchill, 1985) when terrestrial organisms were adapting to life on land, thus have evolved concurrently ever since. Collembola are the microarthropods that have been implicated in helping to facilitate moss sexual reproduction as they move about in the canopies , in essence relieving the "swimming" moss sperm of steep barriers to overcome.…”

Section: Discussionmentioning

confidence: 99%

“…The most basal extant relatives of modern bryophytes are some of the Earth's first terrestrial plants, dating back to the mid-late Ordovician, about 450 Mya (Kenrick & Crane, 1997). A derived trait of all subsequent land plants is that they are embryophytes, meaning that the female egg is stationary and once fertilized, develops into an ovary that is nourished by the female to maturation (Island & Arctic, 2001, Mishler & Churchill, 1985, thus anchoring the plants and requiring the development of dispersal mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Testing the Ecological and Physiological Factors Influencing Reproductive Success in Mosses

Shortlidge¹

2000

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As non-vascular, early land plants with an aquatic ancestry, mosses do not regulate internal water conditions separate from that of their environment and as a result, evolved mechanisms to survive in a terrestrial world out of water. Yet, there is a widely accepted dogma that moss reproductive success is solely dependent on rainfall events carrying swimming, bi-flagellate sperm across the landscape to reproductively mature and receptive female mosses -

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“…Naiadita) provide tantalizing combinations of characters not seen in extant form (Hemsley 1989). An alternative approach is prompted by Mishler & Churchill's (1985) reconstruction of a number of archetypes based on shared homologies. Thus, for example, the archetype of land plants was reconstructed as a thalloid gametophyte with single sessile sporangium and that for the moss-tracheophyte clade as a radially symmetrical, lea£ess, branched gametophyte with conducting tissues and stomata.…”

Section: Discussionmentioning

confidence: 99%

The role of Mid-Palaeozoic mesofossils in the detection of early bryophytes

Edwards

2000

Phil. Trans. R. Soc. Lond. B

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Recently discovered Silurian and Devonian coali¢ed mesofossils provide an additional source of data on early embryophytes. Those reviewed in this paper are considered of some relevance to understanding the early history of bryophytes while highlighting the di¤culties of recognizing bryophytes in often very fragmentary fossils. The ¢rst group comprises sporophytes in which terminal sporangia contain permanent dyads and tetrads. Such spores (cryptospores) are similar to those found dispersed in older Ordovician and Silurian strata, when they are considered evidence for a land vegetation of embryophytes at a bryophyte grade. The phylogenetic signi¢cance of plants, where the axes associated with both dyadand tetrad-containing sporangia are branching, a character state not found in extant bryophytes, is discussed. The second group comprises axial fossils, many with occasional stomata, in which central conducting strands include G-type tracheids and a number of novel types of elongate elements not readily compared with those of any tracheophyte. They include smooth-walled, evenly thickened elongate elements as well as those with numerous branching § anastomosing projections into the lumen. Some of the latter bear an additional microporate layer, but the homogenized lateral walls between adjacent cells are never perforate. Such cells, which occur in various combinations in central strands, are compared with the leptoids and hydroids of mosses, hydroids of liverworts and presumed water-conducting cells in coeval Lower Devonian plants such as Aglaophyton. It is concluded that lack of information on the chemistry of their walls hampers sensible assessment of their functions and the a¤nities of the plants. Finally, a minute fossil, comprising an elongate sporangium in which a central cylindrical cavity containing spores and possible elaters terminates in a complex poral dehiscence apparatus, is used to exemplify problems of identifying early bryophytes. It is concluded that further progress necessitates the discovery of pre-Upper Silurian fossils with well-preserved anatomy, as well as a re-evaluation of criteria used to assess existing and new Devonian fossils for bryophyte a¤nity.

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Transition to a Land Flora: Phylogenetic Relationships of the Green Algae and Bryophytes

Cited by 215 publications

References 31 publications

Regulatory network analysis reveals novel regulators of seed desiccation tolerance in Arabidopsis thaliana

Regulatory network analysis reveals novel regulators of seed desiccation tolerance in Arabidopsis thaliana

Testing the Ecological and Physiological Factors Influencing Reproductive Success in Mosses

The role of Mid-Palaeozoic mesofossils in the detection of early bryophytes

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