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Abstract Detail

A Broader view for Plant EvoDevo: novel approaches for diverse model systems

Ambrose, Barbara [1], Smalls, Tynisha [1], Vasco, Alejandra [2].

Evolution and development in lycophytes and ferns.

Biologists have been intrigued by the origin of novelties for centuries. Leaves are novel plant organs and can serve as an excellent model for understanding the origin and evolution of novelties. Morphological, paleobotanical, and phylogenetic analyses have failed to concur on the origin of leaves or even how many times leaves have evolved in vascular plants. In addition, previous comparative expression analyses in lycophytes and seed plants have come to diametrically opposed conclusions about the conservation of a leaf developmental program. However, these same studies concluded that their comparative analyses provided support for popular theories of leaf evolution and that leaves originated as de novo structures in lycophytes or from branching axes in seed plants. We conducted phylogenetic analyses of leaf developmental gene families (Class III HD-Zip, KNOX, CUC) across land plants with extensive new data across lycophytes and ferns. We also utilized comparative expression analyses of orthologous genes by in situ hybridization. We performed our expression analyses in both vegetative and reproductive organs of lycophytes and ferns. Here, we provide the first expression analyses of Class III HD-Zip genes from ferns and map a duplication at the base of the ferns and seed plants with a neo-functionalization of Class III HD-Zips adaxial leaf expression. This is the first molecular genetic support indicating a conservation in a leaf developmental program between ferns and seed plants. In addition, our results show Class III HD-Zip expression in sporangia (reproductive organs) across lycophytes and ferns. This provides the first molecular genetic evidence that a sporangia developmental network was co-opted independently for the evolution of all leaves. Furthermore this shifts the paradigm of lycophyte leaf evolution from the widely cited enation theory (de novo origin) to the sterilization of sporangia theory.

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1 - The New York Botanical Garden, 2900 Southern Blvd., Bronx, NY, 10458, USA
2 - Universidad Nacional Autónoma de México, Departamento de Botánica, Circuito Exterior s/n, Ciudad Universitaria, Mexico , DF, 04510, Mexico

evo devo.

Presentation Type: Symposium Presentation
Session: SY02
Location: Salon 11/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 9:15 AM
Number: SY02004
Abstract ID:580
Candidate for Awards:None

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