Evolutionary Developmental Biology (Evo-Devo)
Williams, Tim , Rothwell, Gar , Wyatt, Sarah .
Rescuing a fossil morphology with exogenous auxin treatments of Isoetes.
Lycopsids and seed plants independently evolved a number of traits including bipolar growth initiating in the embryo that allowed each lineage to evolve trees. Isoetes, which has retained bipolar growth, serves as a model system as the only living genus of lycopsid, or arborescent lycophyte. The lycopsid rooting structure, the rhizomorph, is a shoot modified for rooting. Isoetes' rhizomorph bears a linear meristem, as do all cormose rhizomorphs in the fossil record. A linear rhizomorph meristem is associated with a lack of stem elongation, and a radial meristem is associated with shoot elongation in the fossil lycopsids. The plant growth regulator auxin is known to regulate stem elongation and may participate in determining the rhizomorph morphology. An auxin-induced transition from linear to radial rhizomorph meristem has been documented in Isoetes, however, it left the relationship to shoot elongation unexplored. We found the afore-mentioned research irreproducible with the reported methods and have sought the auxin-induced morphological change via modified techniques. Our auxin-treated Isoetes engelmannii had significant stem growth, a previously undocumented auxin response. The hypothesized transition to a radial rhizomorph meristem is anticipated but not yet observed. Through the reproduction of auxinic changes in the stem of Isoetes, we show that the link between auxin and morphology is feasibly testable in a controlled setting.
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1 - Ohio University, Environmental And Plant Biology, 536 Richland Ave, Athens, OH, 45701, USA
2 - Oregon State University, Department of Botany and Plant Pathology, 2082 Cordley Hall, Corvallis, OR, 97330, USA
3 - Ohio University, 315 Porter Hall, Athens, OH, 45701, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Delaware C/Hyatt
Date: Tuesday, July 10th, 2012
Time: 8:15 AM