Molecular cloning and analysis of Cu/Zn superoxide dismutase and catalase gene of Chinese cabbage (Brassica campestris L. ssp. Pekinensis)

2005

A:PS

Superoxide dismutase (SODs) are metalloenzymes that are ubiquitous among aerobic organisms and are very efficient at scavenging O2 -. Hydrogen peroxide (H2O2) is synthesized as a byproduct of photorespiration, -oxidation of fatty acid, and also as a consequence of biotic and abiotic stresses. Catalase (CAT) is the primary H2O2 scavenger in peroxisomes of leaves. A cDNA library was constructed using polyA RNA from 800 ppb sulfur-dioxide-fumigated Chinese cabbage leaves for 7 hours. The cDNA library was screened for the sod and cat genes by using a maize sod4 and catl as probe. The insert of pSOD62 (sod62) has 754 bp deduces an open reading frame of 152 amino acids. The longest and complete inserts was found in pCAT78 of 1694 bp containing an open reading frame of 492 amino acids. The sod62 and cal78 protein and SOD and CAT specific activity could be detected using SDS-PAGE and native PAGE by introduction of sod62 and cat78 into E. coli expression vector. High levels of sod62 and cat78 mRNA could be detected in Chinese cabbage after 1.hour of200 JiM of MY treatment, and remained prominent thereafter till 24 hours.

v.31(2):55-74, HORTICULTURE NCHU

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