Contrasting the morphology, anatomy and fungal colonization of new pioneer and fibrous roots
Article first published online: 6 JAN 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 190, Issue 1, pages 213–221, April 2011
How to Cite
Zadworny, M. and Eissenstat, D. M. (2011), Contrasting the morphology, anatomy and fungal colonization of new pioneer and fibrous roots. New Phytologist, 190: 213–221. doi: 10.1111/j.1469-8137.2010.03598.x
- Issue published online: 25 FEB 2011
- Article first published online: 6 JAN 2011
- Received: 13 September 2010, Accepted: 17 November 2010
- root construction;
- root lifespan
- •Not all roots born as first-order branches are the same and this has important consequences for overall function. We hypothesized that, compared with fibrous roots, pioneer roots are built to live longer at the expense of absorptive capacity.
- •We tested this hypothesis by investigating pioneer and fibrous roots in their first 14 d of life in the arbuscular mycorrhizal tree species: Acer negundo, Acer saccharum, Juglans nigra, Liriodendron tulipifera and Populus tremuloides. Root observations were made with root-access boxes that allowed roots to be sampled at known ages in field-grown trees.
- •Compared to fibrous roots, pioneer roots had larger diameter, lower specific root length, greater average length and a lack of mycorrhizal or nonmycorrhizal fungal colonization. Pioneer roots < 14 d old had more layers of hypodermis with a lower percentage of putative passage cells and more protoxylem groups than similar age fibrous roots.
- •Our results suggest that pioneer roots are constructed for defense against biotic and abiotic challenges, exploration of soil distal to the stem, high fibrous root branching and secondary development with high axial hydraulic conductivity at the expense of mycorrhizal colonization and high absorptive capacity for water and nutrients.