Study of sponge gourd ascorbate peroxidase and winter squash superoxide dismutase under respective flooding and chilling stresses

- Bitter melon (BM) is grafted onto sponge gourd (SG) for flooding stress.
- Bitter melon (BM) is grafted onto winter squash (WS) for chilling stress.
- APX activity of SG was significantly higher than that of BM during flooding.
- Increases in SOD activity of WS were observed under chilling compared to BM.
- APX and SOD activities can be used for selecting BM with tolerances to the stresses.

The objectives of this work were to study the responses of ascorbate peroxidase (APX), catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), and physiological parameters of bitter melon (BM), sponge gourd (SG), and winter squash (WS) under waterlogged and low temperature conditions. The BM and SG plants were subjected to 0-72 h flooding treatments. Moreover, BM and WS plants were exposed to chilling at 12/7 °C (day/night) for 0-72 h. The results show that different genotypes responded differently to environmental stress according to their various antioxidant enzymes and physiological parameters. The activity of APX in roots and leaves of SG plants significantly higher than that of BM plants during continuous flooding. Significant increases in SOD activity in leaves of WS plants were also observed throughout the entire chilling duration compared to BM plants. On the basis of our observations, we conclude that increased APX and SOD activities provide SG and WS plants with increased waterlogging and chilling stress tolerance, respectively. Both APX and SOD activities can be used for selecting BM lines with the best tolerances to water logging and chilling stresses.