Abstract Detail

Ecophysiology

Miller, Elise [1], Ray, Dustin [2], Savage, Jessica [3].

Stem diameter limits phloem conductive area plasticity in Populus tremuloides seedlings.

Carbon sources and sinks and plant growth change throughout a plant’s development. In turn, carbon transport, which occurs in the phloem, a vascular tissue, is also altered. However, due to methodological reasons, there is little data on the degree to which the area available for carbon transport, the phloem conductive area, can change in the phloem in response to the environment. To study the plasticity of the phloem conductive area, we grew Populus tremuloides seedlings under three different light treatments (high, medium, and low) for eight weeks. We measured their growth, leaf and root gas exchange, and measured vascular structure using a new immunolabeling technique that stained active sieve elements. Light altered vascular structure at all levels, including the phloem conductive area. Xylem and phloem structure changed similarly except for the percent xylem and phloem conductive area. The percent xylem conductive area was the same under all light treatments while the low light plants had a lower percent phloem conductive area. Thus, there is a driver that affects the phloem conductive area that does not impact the xylem conductive area. Stem diameter was the main driver of differences in the phloem conductive area in all light treatments, which suggests that cross-sectional area may strongly influence the diameter and/or density of sieve elements. These results suggest that the phloem might be more plastic than we previously thought when looking at the actual phloem conductive area, but there are limitations to phloem plasticity.

1 - 19512 Two Rivers Road, Avon, MN, 56310, United States
2 - University of Minnesota - Duluth
3 - University Of Minnesota - Duluth, Biology, 1035 Kirby Drive, 207 Swenson Science Buildling, Duluth, MN, 55812, United States

Keywords:
Phloem
Light
Seedlings
Conductive Area
Sieve Elements
Sources
Sinks.

Presentation Type: Oral Paper
Number: EPH3009
Abstract ID:443
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation