| Summary: | 碩士 === 中國文化大學 === 生物科技研究所 === 100 === Bitter gourd is one of the most important economical vegetables in Taiwan. However, the growth and development of the plants are strongly influenced by flooding and chilling stresses that can be initiated by oxidative stress. Bitter gourds have been grafted onto the sponge gourd and winter squash to cope with flooding and chilling stresses due to its susceptible to both conditions. These scions have developed a series of defense mechanisms and detoxification systems including antioxidants and enzymes to scavenge the reactive oxidative species (ROS). The objectives of our work were to study the changes of physiological parameters in bitter gourd, sponge gourd and winter squash, and identify any antioxidant enzyme under flooding and chilling stresses. The phenotypic traits, physiological parameters (variable fluorescence/maximum fluorescence, electrolyte leakage, malondialdehyde), and antioxidant enzymes (APX, CAT, SOD, and GR) were measured during different time periods of stress.
The results of the study show that the physiological damages include chlorophyll breakdown, membrane permeability increased, and caused lipid peroxidation. The value of Fv/Fm was decreased under flooding and chilling stresses. The APX activity between sponge gourd and bitter gourd was found to be significant difference under flooding stress. APX mRNA transcripts of sponge gourd were relatively higher than bitter gourd based on real-time PCR analysis using actin as internal control.SOD activity between bitter gourd and winter squash was significantly different under chilling stress. Therefore, APX gene from the flooding-tolerant sponge gourd was identified and isolated using RACE technology. Both APX and SOD genes were cloned into E. Coli using transformation methodology. The results may be helpful to those bitter gourd farmers to reduce damages of the plants, and also be informative to screen for suitable scions and for stress tolerant breeding as well.
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