Abstract: Heavy metal stress badly affect the crop growth and development, assuaging heavy metal stress to crop show important for crop yield. Here we investigated the effect of SNP ( sodium nitropprusside, an exogenous nitric oxide donor) on alleviating copper stress and regulating antioxidant gene transcriptional levelin liquid-culture tomato seedlings. Our results showed that copper at 0.5 mmol·L - 1 significantly suppressed the tomato seedlings growth including plant height, stem thickness, plant fresh weight and plant dryweight, as well as improved the transcriptional levels of antioxidant genes encoding peroxidase ( POD) , ascorbate peroxidase (APX) , superoxide dismutase ( SOD) and catalase (CAT). Exogenous application of 0.3 mmol·L - 1 SNP remarkably alleviated copper-inhibition to tomato growth and further enhanced these antioxidant genes transcription, however, additional L-NAME (Nω -nitro-L-arginine methyl ester) , the special inhibitor of nitric oxide synthase (NOS) obviously aggravated copper-induced inhibitory effect on tomato growth and reduced antioxidant enzyme gene transcrip tional level. Basing on these results we propose that tomato NOS enzyme-mediated NO is necessary for tomato responding to copper stress and NO application lessen copper stress to tomato growth via enhancing antioxidant enzyme gene transcriptional levels.

Key words: copper stress, tomato, RT-PCR