Current address: Laboratory of Agronomy, School of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
Expression of a stress-induced hemoglobin affects NO levels produced by alfalfa root cultures under hypoxic stress
Article first published online: 28 AUG 2003
The Plant Journal
Volume 35, Issue 6, pages 763–770, September 2003
How to Cite
Dordas, C., Hasinoff, B. B., Igamberdiev, A. U., Manac'h, N., Rivoal, J. and Hill, R. D. (2003), Expression of a stress-induced hemoglobin affects NO levels produced by alfalfa root cultures under hypoxic stress. The Plant Journal, 35: 763–770. doi: 10.1046/j.1365-313X.2003.01846.x
- Issue published online: 28 AUG 2003
- Article first published online: 28 AUG 2003
- Received 21 March 2003; revised 25 May 2003; accepted 20 June 2003.
- hypoxic stress;
- nitric oxide;
- root growth
Transgenic alfalfa root cultures expressing sense and antisense barley hemoglobin transcripts were examined under varying levels of atmospheric oxygen. Root cultures overexpressing the hemoglobin gene (Hb+) maintained root growth when placed under 3% oxygen, whereas control cultures or cultures underexpressing hemoglobin (Hb−) experienced 30–70% declines in growth under the same conditions. ATP levels and ATP/ADP ratios for Hb+ lines did not significantly differ in 40 and 3% oxygen, whereas the ATP levels and ATP/ADP ratios in control and Hb− lines were significantly lower under 3% oxygen. Large increases in the production of nitric oxide (NO) were measured in root cultures grown under hypoxic conditions compared to aerobic conditions. The amount of NO accumulated in an Hb− line was 2.5-fold higher than that in the Hb+ line. Treatment of transgenic root lines under 40% oxygen with NO resulted in significant declines in the ATP levels and ATP/ADP ratio of an Hb− line and the control line, with no significant change in an Hb+ line. The root cell structure of an Hb− line showed evidence of cell breakdown under hypoxic growth, whereas an Hb+ line had no evidence of cell breakdown under similar growth conditions. These results lead us to hypothesize that NO is involved in the response of plants to hypoxia and that hemoglobin modulates the levels of NO in the hypoxic cell.