Abstract Detail

Ecophysiology

Crone, Emily [1], Morris, Catherine [1], Boyd, Robert [2], Watkins, James [3].

Physiological responses of the serpentine endemic Strepthanthus polygaloides (Brassicaceae) to varying levels of Ni and CO₂.

Heavy metals are known to be toxic to biological systems. However, some plants grow on naturally high metal soils and may accumulate high levels of heavy metals. To date, much work has investigated why plants take up metals and these hypotheses range from mediation of drought stress to protection from herbivory. Relatively little is known about physiological effects of heavy metals on plants adapted to serpentine soils. Strepthanthus polygaloides (Brassicaceae) is a serpentine endemic and, unlike other species in the genus, hyperaccumulates Ni, reaching leaf Ni concentrations of 20,000 mg kg-1 dry weight. The goal of this study is to examine the physiological responses of a nickel hyperaccumulator to varying levels of nickel and CO₂. To examine this, 25 S. polygaloides plants were grown in each of four hydroponics systems: control (0% Ni), 1% Ni, 2% Ni, and 4% Ni (all at ambient CO₂ concentration), and at 2% Ni in high and low CO₂ concentration. After two months, a number of physiological measurements were carried out using a LiCOR 6400 to determine maximum photosynthetic and respiration rates, quantum yield, light compensation and saturation estimates and a modulated fluorometer to estimate Fv/Fm and ETR. We found that plants in the 4% Ni solution were the most stressed and those in 2% Ni solution exhibited the highest values for physiological parameters relative to the control and other treatments; elevated CO₂ amplified this response in the 2% solution. These data reveal that heavy metal hyperaccumulating plants require what would otherwise be toxic levels of nickel to reach their peak physiological performance. In spite of their ability to hyperaccumulate nickel in nature, in hydroponics relatively low concentrations of available nickel can be toxic. Future studies will examine how nickel accumulation affects drought tolerance in this heavy metal accumulating plant and how this may impact the species’ distribution in the field.

Broader Impacts:

1 - Colgate University, Biology, 13 Oak Dr, Hamilton, NY, 13346, United States
2 - Auburn University, Department of Biological Sciences, 101 LIFE SCIENCES BLDG, AUBURN UNIVERSITY, AL, 36849-5407, USA
3 - Colgate University, Department of Botany, 129 Ho Science Center, 13 Oak Drive, Hamilton, NY, 13346-1338, USA, 315-228-7660

Keywords:
hyperaccumulation
serpentine
photosynthesis
plant stress.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PEP010
Abstract ID:445
Candidate for Awards:None