Functional Analysis Of The CDR6 Gene Involved In The Regulation Of Lead Stress Response In Arabidopsis

Heavy metal pollution is a serious environmental problem, which hazards human health through food chain. It could be theoretically resolved through plant recovery technique in combination with plant genetic engineering, which depending on our understanding on the mechanisms of plant heavy metal tolerance. In our previous work, we found that the transcript level of CDR6 was induced by lead stress in Arabidopsis. In this study, the biological function of CDR6 was analyzed in regulation the lead tolerance of plants. The results were as follows:1. The expression pattern of CDR6 was analyzed by using quantitative RT-PCR and histochemical methods. It was found that this gene was detected in most tissues of Arabidopsis plants, including root, rosette leaf, stem, silique and flower, with higher expression in flower, stem and silique. Transgenic lines of ProCDR6::GUS were obtained, and results of histochemical staining were shown to be in consistent with those of qRT-PCR.2. The subcellular localization of CDR6 was analyzed in transgenic lines of 35S: CDR6-GFP by using laser confocal microscopy. The result showed that this fusion protein was localized in cytoplasm.3. The cdr6-1 homozygous mutant was isolated and characterized by molecular and genetic methods. The construct of 35S::CDR6 was built and transformed to wild-type plants by the floral dip method, and transgenic lines were screened and identified.4. Heavy metal tolerance of cdr6-1 and 35S::CDR6 transgenic lines were analyzed under lead stress. cdr6-1 mutant plants showed significantly higher tolerances, while 35S..CDR6 transgenic plants showed significantly sensitivities.5. In order to analyze the biological role of CDR6 in lead tolerance, the transcript levels of candidate genes were analyzed in cdr6-1 mutant by qRT-PCR, including AtPDR12, ATM3, GSH1 and GSH2. It was found that the expression of AtPDR12, GSH1 and PCS1 in cdr6-1 plants-was no significantly difference compared with the wild type, but the transcript level of ATM3 was significantly increased in cdr6-1 mutant. The result suggests that ATM3 is regulated by CDR6 in response of plants to lead stress.All these results suggest that CDR6 participates in regulating lead stress response.