Heterologous expression of Arabidopsis NPR1 (AtNPR1) enhances oxidative stress tolerance in transgenic tobacco plants
In Arabidopsis, NPR1 (non-expressor of pathogenesis related genes 1, AtNPR1) functions downstream of salicylic acid (SA) and modulates the SA mediated systemic acquired resistance. It is also involved in a cross talk with the jasmonate pathway that is essential for resistance against herbivores and necrotrophic pathogens. Overexpression of AtNPR1 in transgenic plants resulted in enhanced disease resistance. Recently, tobacco transgenic plants expressing AtNPR1 were shown to be tolerant to the early instars of Spodoptera litura (Meur et al., Physiol Plant 133:765–775, 2008). In this communication, we show that the heterologous expression of AtNPR1 in tobacco has also enhanced the oxidative stress tolerance. The transgenic plants exhibited enhanced tolerance to the treatment with methyl viologen. This tolerance was associated with the constitutive upregulation of PR1, PR2 (glucanase), PR5 (thaumatin like protein), ascorbate peroxidase (APX) and Cu2+/Zn2+ superoxide dismutase (SOD). This is the first demonstration of the novel function of heterologous expression of AtNPR1 in oxidative stress tolerance in transgenic tobacco.
KeywordsAtNPR1 Methyl viologen Oxidative stress tolerance Transgenic tobacco
The work was supported by a Research Grant from the AP-Netherlands Biotechnology Programme administered by the Institute of Public Enterprise, Hyderabad. KRRK and GM have been supported by the CSIR, Government of India in the form of Research Fellowships. The authors thank Ms G. Triveni for proofreading the manuscript. The authors are grateful to DST-FIST (Level-II), UGC-CAS, Government of India, for the facilities provided to the Department of Plant Sciences, University of Hyderabad.
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