CHANGES OF APX ISOZYMES UNDER HIGH-TEMPERATURE STRESS AND CLONING OF AN APX FUNCTIONAL FRAGMENT IN EMBRYOGENIC CALLUS OF LITCHI

In this study, the embryogenic callus (EC) of litchi (Litchi chinensis Sonn.) was used as the material. Activity and isozymes bands of APX were analyzed under high-temperature stress. In the meanwhile, a cytosolic apx gene fragment was cloned. Results showed that the expression of apx genes was differently induced by high-temperature stress. The level of APX activity was higher at the 30 and 35°C than at the control temperature, whereas the activity was lower at 40°C than the control. The strength of APX isozyme bands was also elevated at 30 and 35°C. A new band appeared at the 35°C. Both the strength and the number of the bands decreased at 40°C. The degenerate primers were designed according to amino acid sequences of cAPX from NCBI. A 752 bp specific fragment was obtained by the PCR amplification. Homologous comparation with other plants’ apx genes, the fragment obtained is highly conserved and contains the complete open reading frame.