Patterns of peroxidative ethane emission from submerged rice seedlings indicate that damage from reactive oxygen species takes place during submergence and is not necessarily a post-anoxic phenomenon |
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Authors: | I. E. Santosa P. C. Ram E. I. Boamfa L. J. J. Laarhoven J. Reuss M. B. Jackson F. J. M. Harren |
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Affiliation: | (1) Present address: Physics Department, Sanata Dharma University, Yogyakarta, Indonesia;(2) Centre of Advanced Studies, Department of Crop Physiology, N.D. University of Agriculture and Technology, Kumarganj, Faizabad, India;(3) Life Science Trace Gas Facility, Molecular and Laser Physics, Radboud University, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands;(4) School of Biological Sciences, University of Bristol, Bristol, UK |
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Abstract: | Using ethane as a marker for peroxidative damage to membranes by reactive oxygen species (ROS) we examined the injury of rice seedlings during submergence in the dark. It is often expressed that membrane injury from ROS is a post-submergence phenomenon occurring when oxygen is re-introduced after submergence-induced anoxia. We found that ethane production, from rice seedlings submerged for 24–72 h, was stimulated to 4–37 nl gFW−1, indicating underwater membrane peroxidation. When examined a week later the seedlings were damaged or had died. On de-submergence in air, ethane production rates rose sharply, but fell back to less than 0.1 nl gFW−1 h−1 after 2 h. We compared submergence-susceptible and submergence-tolerant cultivars, submergence starting in the morning (more damage) and in the afternoon (less damage) and investigated different submergence durations. The seedlings showed extensive fatality whenever total ethane emission exceeded about 15 nl gFW−1. Smaller amounts of ethane emission were linked to less extensive injury to leaves. Partial oxygen shortage (O2 levels <1%) imposed for 2 h in gas phase mixtures also stimulated ethane production. In contrast, seedlings under anaerobic gas phase conditions produced no ethane until re-aerated: then a small peak was observed followed by a low, steady ethane production. We conclude that damage during submergence is not associated with extensive anoxia. Instead, injury is linked to membrane peroxidation in seedlings that are partially oxygen deficient while submerged. On return to air, further peroxidation is suppressed within about 2 h indicating effective control of ROS production not evident during submergence itself. |
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Keywords: | Ethane emission Lipid peroxidation Non-invasive technique Oxygen shortage Photoacoustic detection Prolonged hypoxic and anoxic conditions Real time measurements Submerged rice Survival tests and damage assessment |
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