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      Root evolution at the base of the lycophyte clade: insights from an Early Devonian lycophyte

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      Annals of Botany
      Oxford University Press (OUP)

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          Abstract

          <p class="first" id="d5351018e116"> <b>Background and Aims</b> The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology. </p><p id="d5351018e121"> <b>Methods</b> Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian–Pragian (∼411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions. </p><p id="d5351018e126"> <b>Key Results</b> The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved <i>in situ</i> demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme. </p><p id="d5351018e134"> <b>Conclusions</b> This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant–substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily uncoupled in lycophytes, and challenge the hypothesis that roots evolved from branches of the above-ground axial system, suggesting instead that lycophyte roots arose as a novel organ. </p>

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          Most cited references36

          • Record: found
          • Abstract: not found
          • Article: not found

          GEOCARB III: A revised model of atmospheric CO2 over Phanerozoic time

          R. Berner (2001)
            Bookmark
            • Record: found
            • Abstract: not found
            • Article: not found

            COPSE: A new model of biogeochemical cycling over Phanerozoic time

            N. Bergman (2004)
              Bookmark
              • Record: found
              • Abstract: not found
              • Article: not found

              Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events

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                Author and article information

                Journal
                Annals of Botany
                Ann Bot
                Oxford University Press (OUP)
                0305-7364
                1095-8290
                March 29 2016
                April 26 2016
                : 117
                : 4
                : 585-598
                Article
                10.1093/aob/mcw006
                4817433
                26921730
                74fe92c2-d598-483b-90ec-f00bd032755a
                © 2016
                History

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