Hydrogen peroxide acts upstream of nitric oxide in heat shock pathway in Arabidopsis seedings
Lei Wang1, Yunjing Guo1, Shuo Zhou, Lixiu Jia, Liqun Zhao*
College of Life Sciences, Hebei Normal University, Shijiazhuang 050024。
1These authors contributed equally to the work.
*Corresponding Author: Tel:(+86 311)8078 7530; Fax:(+86 311)8078 7549; e-mail: email@example.com
We even reported that nitric oxide (NO) functioned as a signal in thermotolerence. To clarified its relationship with hydrogen peroxide (H2O2), we investigated the effects of heat on three types of Arabidopsis thaliana seedlings: wide type, AtrbohB, AtrbohD and AtrbohB/D (for NADPH oxidase-defective mutants), which all exhibited reduced endogenous H2O2 levels, and noa1(rif1) (for nitric oxide associated1/resistant to inhibition by fosmidomycin1). After heat shock (HS), the NO levels of AtrbohB, AtrbohD and AtrbohB/D seedlings were lower than that of wide type, the lowest one for AtrbohB/D seedlings; however, the H2O2 level of noa1(rif1) seedlings was not clear different from that of wide type. Treatment of AtrbohB, AtrbohD and AtrbohB/D seedlings with H2O2, sodium nitroprusside or S-nitroso-N-acetylpenicillamine revealed that both of internal H2O2 and NO partially rescued their heat sensitivity; however, no obvious effect was observed for noa1(rif1) seedlings after treatment of H2O2, suggesting that NO is involved in H2O2 signal transduction as a downstream factor. This point was verified by phenotypic analysis and thermotolerance testing using seedlings of two nia2 (nitrate reductase 2-mediated NO generation) -overexpressing transgenic lines in an AtrbohB/D background. Electrophoretic mobility-shift and western-blot analyses demonstrated that after HS treatment, H2O2 through NO stimulated the DNA-binding activity of HS transcription factors and the accumulation of heat shock protein 21 (HSP21). These data indicate that H2O2 acts upstream of AtCaM3 in thermotolerance, which is dependent on increased HS transcription factor DNA-binding activity and HSP accumulation.
Key Words: Arabidopsis; heat shock; hydrogen peroxide; nitric oxide