Abstract Detail

Xylem apoplast-symplast interactions

Tepler, Sarah [1], Prentice, Paige [2], Baer, Alex [2], Knoblauch, Michael [3], Pittermann, Jarmila [4].

Allometric relationships and functional morphology of long-distance vascular transport in large brown seaweeds.

Large brown seaweeds in the order Heterokontophyta are important ecosystem engineers, playing a role similar to that of trees in terrestrial forest ecosystems. They provide habitat and nutrients that support a diverse fauna, and biochemically alter their physical medium. Their size (up to 40 m tall), organ specialization, and ability of individuals to tolerate steep abiotic resource gradients has likely been facilitated by their evolution of a phloem-like vascular system. This phloem-like vascular system features transport cells (sieve elements) with sieve plates and trumpet-shaped cell junctions—a remarkable case of convergent evolution with terrestrial plants. We understand very little about the mechanisms, constraints, and variability of brown algal sieve elements. To gain such an understanding, we have assessed for the first time the allometric relationships of sieve elements to various gross anatomical and physiological traits in 6 species of large brown seaweeds off the coast of Central California. The 6 species — Alaria marginata, Egregia menzezii, Laminaria setchellii, Macrocystis pyrifera, Nereocystis luetkeana, and Pterygophora californica—span a wide range of life-histories, habitats, and taxonomic groups, giving us the potential to identify drivers and constraints on long-distance transport. Preliminary results indicate a remarkable homogeneity of sieve element size amongst different species with the exception of M. pyrifera and N. luetkeana, closely-related seaweeds that grow exponentially taller and produce more biomass than any other brown seaweeds in the northern hemisphere. Strong allometric relationships are observed with plant height, vascular fraction, conduit packing, and cumulative blade (leaf) area, indicating a unifying pattern of resource allocation that varies based on the meristem location and ontogenetic strategy of each species. Finally, transmission electron microscopy and fluorescent dye tracer studies allow us to move closer to understanding the elusive mechanisms of loading and transport in this poorly-studied system.

Broader Impacts:

1 - University of California, Santa Cruz, 100 Shaffer Road, Santa Cruz, CA, N/A, 95060, USA
2 - University of California, Santa Cruz
3 - Washington State University, Plant Cell Biology, PO Box 644236, Pullman, Washington (WA), 99164-4236
4 - University of California, Integrative Biology, 1156 High Street, Santa Cruz, CA, 95064, USA

Keywords:
seaweed
Heterokontophyta
phloem
sieve elements
allometry.

Presentation Type: Symposium or Colloquium Presentation
Session: C3
Location: Belle-Chasse/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 9:00 AM
Number: C3005
Abstract ID:585
Candidate for Awards:None