Abstract Detail

Anatomy and Morphology

Cox, Monica [1], HORNER, HARRY T [2], Gallaher, Timothy [3], Clark, Lynn [1].

Grass Roots (Poaceae) at Work: Uncovering their Anatomy and Functional Roles.

A survey of transectional root anatomy in the Poaceae, by sampling over 80 species representing all 12 subfamilies from herbarium specimens, has been completed. These species are a subset of over 150 for which plastomes, and leaf shape and leaf anatomical data are available. Quantitative and qualitative characters, including endodermal cell depth, number of endodermis and pericycle layers, stele area and metaxylem vessel diameter, were measured or scored. Some ratios, such as total metaxylem area to stele area, were calculated. More variation than expected from relatively sparse reports in the literature was uncovered and two unique features, internal phloem and a multiple endodermis, were documented. Internal phloem was confirmed for a few species in Micrairoideae, whereas a multiple endodermis (of up to five layers) was found in a number of species in several subfamilies. These characters have been coded and their evolution is being explored using character state optimization and ancestral state reconstruction based on the plastome phylogeny for these taxa. Functional root anatomy is being explored through correlating these root anatomical characters with photosynthetic type (C₃ vs. C₄), life cycle (annual vs. perennial), light regime (open vs. shaded), and climate variables. Preliminary results indicate correlation between photosynthetic type and several anatomical characters. Furthermore, there is evidence of a significant correlation between habitat and the number of pericycle layers, as well as stele diameter. Light regime and various metaxylem characteristics also seem to be correlated, but most interesting is the significance between habitat and the extent of thickening present in the innermost endodermal cell wall. This character, in turn, affects the ratio of endodermal cell depth to endodermal cell wall thickening. Relationships to life span are still under analysis, in addition to phylogenetic optimizations.

1 - Iowa State University, Department Of Ecology, Evolution, And Organismal Biology, 251 Bessey Hall, Ames, IA, 50011-1020, USA
2 - Iowa State University, Department of Genetics, Development, and Cell Biology, 2200 Osborn Drive, 3A Bessey Hall, Ames, IA, 50011-4009, USA
3 - University of Washington, Department of Biology, 24 Kincaid Hall, Seattle, WA, 98195, USA

Keywords:
Poaceae
anatomy
root
Monocots.

Presentation Type: Oral Paper
Session: 20, Anatomy and Morphology
Location: Fort Worth Ballroom 7/Omni Hotel
Date: Tuesday, June 27th, 2017
Time: 8:45 AM
Number: 20004
Abstract ID:301
Candidate for Awards:Katherine Esau Award,Maynard F. Moseley Award