Stepwise and independent origins of roots among land plants.

ABSTRACT: Roots are one of the three fundamental organ systems of vascular plants¹, and have roles in anchorage, symbiosis, and nutrient and water uptake^2-4. However, the fragmentary nature of the fossil record obscures the origins of roots and makes it difficult to identify when the sole defining characteristic of extant roots-the presence of self-renewing structures called root meristems that are covered by a root cap at their apex^1-9-evolved. Here we report the discovery of what are-to our knowledge-the oldest meristems of rooting axes, found in the earliest-preserved terrestrial ecosystem¹⁰ (the 407-million-year-old Rhynie chert). These meristems, which belonged to the lycopsid Asteroxylon mackiei^11-14, lacked root caps and instead developed

SUBMITTER: Hetherington AJ 

PROVIDER: S-EPMC6175059 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature