Abstract Detail

Developmental and Structural Section

Barone Lumaga, Maria Rosaria [1], Coiro, Mario [2], Erdei, Boglarka [3], Mickle, James [4].

Cuticle micromorphology in cycads: What is the role of ecological pressures?

Classically the phylogeny of cycads have been mainly based on macro-morphology. Recent works based on molecular data have rearranged the cycads phylogeny, and suggested that the extant cycads diversity is the result of a Miocene-Pliocene radiation, probably triggered by increased aridity and seasonality. This study was carried on all extant cycads genera to investigate whether leaf cuticle micromorphology reflects phylogenetic relationships among species, and if it is influenced by ecological pressures. Whole leaf and isolated cuticle specimens from 42 cycads species were examined using SEM for features of inner and external surfaces. Samples were collected from the middle region of leaflets of mature leaves. For external surfaces, samples were air dried or fixed in FAA (10:5:50) and critical-point dried. For the inner cuticle surface, isolated cuticles were obtained using 20% CrO3. The stomata and cuticle micromorphology as well as the distribution of different kinds of epicuticular waxes in the species considered coarsely reflect the phylogenetic patterns emerged from molecular analyses. Besides, it was possible to detect additional patterns in cuticle micro-morphology characters probably related to ecological pressures. In particular, epicuticular wax occurs as granules to ridges bordering the stomata pits in C. euryphyllidia, C. miqueliana, C. norstogii and as reticulate ridges in C. hildae, C. kuesteriana, C. latifolia, C. mexicana. The differences in cuticle morphology closely follow the geographic distribution of studied species and their habitat. Moreover, the closeness of Stangeria eriopus to the other taxa is not supported by cuticle micromorphology. However, the peculiarities detected in this monotypic genus could be explained as the consequence of the adaptation of leaf surface to water repellency.

Broader Impacts:

1 - ORTO BOTANICO, VIA FORIA 223, NAPOLI, I-80139, Italy
2 - ETH Zürich, Department of Biology, Universitätstrasse 2, Zürich, 8092 , Switzerland
3 - Hungarian Natural History Museum, Botanical Department, Post Office Box 222, Budapest, 1476, Hungary
4 - North Carolina State University, Department of Plant Biology, Campus Box 7612, 2115 Gardner Hall, Raleigh, NC, 27695-7612, USA

Keywords:
cycad
plant cuticle
cuticular micromorphology.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PDS008
Abstract ID:313
Candidate for Awards:None