Differential antioxidative responses in transgenic peanut bear no relationship to their superior transpiration efficiency under drought stress

• Published in: Journal of plant physiology Vol. 166; no. 11; pp. 1207 - 1217
• Main Authors: Bhatnagar-Mathur, Pooja, Devi, M. Jyostna, Vadez, Vincent, Sharma, Kiran K.
• Format: Journal Article
• Language: English
• Published: Munich Elsevier GmbH 15-07-2009; Elsevier
• Subjects: antioxidant activity; Antioxidants; Antioxidants - metabolism; Arabidopsis Proteins - genetics; Arabidopsis thaliana; Arachis - genetics; Arachis - metabolism; Arachis - physiology; Arachis hypogaea; ascorbate peroxidase; Ascorbate Peroxidases; Biological and medical sciences; dehydration response element binding protein B1; drought; Drought stress; Droughts; enzyme activity; free radicals; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - genetics; Gene Expression Regulation, Plant - physiology; gene overexpression; glutathione reductase (NADPH); Glutathione Reductase - metabolism; lipid peroxidation; Lipid Peroxidation - physiology; Oxidative Stress - physiology; peanuts; Peroxidases - metabolism; physiological response; Plant physiology and development; plant proteins; plant response; plant stress; Plant Transpiration - physiology; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - physiology; Proline; soil water; superoxide dismutase; Superoxide Dismutase - metabolism; transcription factors; Transcription Factors - genetics; transgenes; Transgenic peanut; transgenic plants; transpiration; Transpiration efficiency; water stress; WW; Antioxidants; TE; FTSW; Transpiration efficiency; Transgenic peanut; Drought stress; Proline; NTR; DS; Response differentiation; Arachis hypogaea; Antioxidant; Water stress; Transpiration; Relation; Leguminosae; Plant physiology; Efficiency; Dicotyledones; Angiospermae; Spermatophyta; Transgenic plant; Drought; Oil plant (vegetal)
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/j.jplph.2009.01.001

To counter the effects of environmental stresses, the plants must undergo detoxification that is crucial to avoid the accumulation of damaging free oxygen radicals (ROI). Here, we detail the oxidative damage, the antioxidant composition, and the osmoprotection achieved in transgenic plants of peanut overexpressing the
AtDREB1A transgene, driven by a stress-inducible promoter (
Atrd29A) when exposed to progressive water stress conditions. This study explored the biochemical mechanisms where (i) the antioxidants such as superoxide dismutase (SOD), ascorbate peroxidase (APOX), and glutathione reductase (GR) accumulated in the transgenic plants at comparably higher levels than their untransformed counterparts under dry soil conditions, (ii) a significant increase in the proline levels in the transgenic plants was observed in dry soils, and (iii) a dramatic increase in the lipid peroxidation in the untransformed controls in drier soils. Most of the biochemical parameters related to the antioxidative machinery in the tested peanut transgenics were triggered by the overexpression of
AtDREB1A that appeared to differ from the untransformed controls. The antioxidants showed a negative correlation with the fraction of transpirable soil water (FTSW) thresholds, where the normalized transpiration rate (NTR) started decreasing in the tested plants. However, no significant relationship was observed between any of these biochemical indicators and the higher transpiration efficiency (TE) values found in the transgenic events. Our results show that changes in the antioxidative machinery in these transgenic peanut plants (overexpressing the
AtDREB1A transcription factor) under water-limiting conditions played no causative role in improved TE.