Changes in expression of the cytosolic ascorbate peroxidase gene,ca-capx1, during germination and development of hot pepper seedlings |
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Authors: | Sung -Chae Moon Soon Il Kvvon Chung Sun An |
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Institution: | 1. Department of Biological Sciences, Seoul National University, 151-742, Seoul, Korea
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Abstract: | Ascorbate peroxidase (APX), an antioxidant enzyme, scavenges H2O2 that is produced by normal metabolism and cellular oxidative stresses. To investigate its role during germination and seedling
growth, we isolated a cDNA encoding cytosolic APX (cAPX) in hot pepper(Capsicum annuum L). The full-length clone,Ca- cAPX1, is 1011 bp long and has an ORF encoding 249 amino acid residues. During seedling development, cAPX activity and expression
levels were higher at Days 5 and 6 post-imbibition, respectively, whereas those of catalase (CAT) increased at Days 8 and
10. The increased amount of H2O2 in that early developmental stage (Day 5) may have been counteracted mainly by APX, and further removed by CAT in cooperation
with APX. To determine whether the accumulation of H2O2 via suppression ofcAPX expression might be a factor in stimulating germination, we constructed a transformant ofCaAPX1. Compared with the wild type, the germination rate for the antisense-suppressedArabidopsis increased by 26%, while its H2O2 content rose by 50%. Therefore, we propose that the pre-germination suppression ofcAPX expression stimulates seed germination by promoting the accumulation of H2O2. |
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