Meeting Abstract

P1.59  Friday, Jan. 4  Transcriptome analyses of the rhizophore in Selaginella apoda GEBER, A*; SMALLS, T; PALMER, M; AMBROSE, B; Columbia University; The New York Botanical Garden; The New York Botanical Garden; Columbia University abg2143@columbia.edu

The lycophytes (Division Lycopodiophyta) comprise the oldest extant group of vascular plants at approximately 410 million years old. As such, they represent an archaic timepoint in the evolutionary history of plants, especially with regard to their modes of reproduction, their leaf morphology, and their meristem growth and branching patterns. Studies of stem morphology and anatomy have shown that most members of the genus Selaginella possess angle meristems, centers of developmental potential that arise de novo at stem branch junctions. While the axillary shoots of higher plants have fixed cell fates, the angle meristem has the capacity to develop in a context-dependent manner as either a new shoot or as a rhizophore, a root-bearing organ. The identity of the rhizophore is highly debated; it has been classified historically as a root, a shoot, and an organ in its own right according to lines of developmental and physiological evidence. Comparative transcriptomics of the root, shoot, and rhizophore tissues of Selaginella apoda have yielded insight into the nature of the rhizophore. Taken in conjunction with morphological and anatomical studies of the meristems in several species of Selaginella, these findings have potential implications for understanding the evolutionary history of root development.