© 2008 The Author(s).
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
This paper is available online free of all access charges (see http://jxb.oxfordjournals.org/open_access.html for further details)
RESEARCH PAPER |
Short-term and long-term root respiratory acclimation to elevated temperatures associated with root thermotolerance for two Agrostis grass species
1The Jacob Blaustein Institute for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990 Israel
2School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, Crawley, WA 6009, Australia
3Department of Plant Biology and Pathology, Cook College, Rutgers University, New Brunswick, NJ 08901-8520, USA
* To whom correspondence should be addressed: E-mail: huang{at}aesop.rutgers.edu
This study was designed to investigate whether thermotolerant roots exhibit respiratory acclimation to elevated temperatures. Root respiratory acclimation traits in response to increasing temperatures were compared between two Agrostis species contrasting in heat tolerance: thermal A. scabra and heat-sensitive A. stolonifera. Roots of both species were exposed to 17, 27, or 37 °C. Root RGR declined with increasing temperatures from 17 °C to 37 °C in both species; however, root growth of A. scabra maintained a significantly higher RGR than A. stolonifera at 27 °C or 37°C. A. scabra exhibited a significantly higher respiration acclimation potential to elevated temperatures, both in the short term (60 min) and in the long term (7–28 d) as compared with A. stolonifera, when temperatures increased from 17 °C to 27 °C or from 27 °C to 37 °C. Thermal A. scabra also maintained a significantly lower maintenance cost than A. stolonifera as temperatures increased to 27 °C or 37 °C. The results suggested that root thermotolerance of thermal A. scabra was associated with both short-term and long-term respiratory acclimation to changes in temperatures. The superior ability of adjusting the rate of root respiration to compensate for increases in carbon demand during short- or long-term temperature increases in the heat-tolerant A. scabra may result in the reduction in carbon expenditure or costs for maintenance, leading to extended root survivability in high temperature soils.
Key words: Acclimation, grass, heat tolerance, high temperature, root respiration
Received 7 May 2008; Revised 22 July 2008 Accepted 5 August 2008