Study Of Parp Function In Plants

Poly(ADP-ribose) polymerase(PARP)is a post-translational modification enzyme which exists in eukaryote cells, except yeasts. PARP cleaves the substrate molecule, NAD+, to nicotinamide and ADP-ribose and attaches the latter one onto the acceptor proteins to form a long poly(ADP-ribose) chain, thus changing the physiological and biochemical activities of the target proteins. There are three PARPs in Arabidopsis, among which PARP-1 and PARP-2 are located in the nucleus. We found that PARP-1 can interact with PARP-2 by yeast-two hybridization. The PARP inhibitor 3-AB was used to study the function of PARPs in vivo, since PARP-1 and PARP-2 null mutants have not been identified. Root development of Arabidopsis was strongly stimulated after treated with 3-AB. The treated plants have more lateral roots compared with the control plants. In Arabidopsis seedlings, GUS staining also showed that PARP-1 was expressed at the base of the major roots, where lateral roots initiated from. We conclude that PARP-1 may regulate the development of lateral roots in vivo.We found that, other than increases the lateral roots and fresh weight,3-AB also enhances the tolerance to drought.3-AB-treated Arabidopsis has stronger drought tolerance than control plant. Its homolog BA has the similar effect. Apart from Arabidopsis,3-AB was able to enhance the lateral root growth of Tobacco, Maize,and Bean as well, suggesting its applicable potential in agricultural production. Poly(ADP-ribose) polymerase (PARP) is a post-translational modification enzyme which exists in eukaryote cells, except yeasts. PARP cleaves the substrate molecule NAD+, to nicotinamide and ADP-ribose and attaches the latter one onto the acceptor proteins, thus changing the physiological and biochemical activities of the target proteins.In order to investigate the tissue-specific expression pattern of PARP-1 in Arabidopsis, the 2179bp promoter region of PARP-1 gene was cloned, fused with GUS gene and transformed into wild-type Arabidopsis. The promoter activity of PARP-1 was studied by GUS staining. The GUS signals were detected in filament and the early-stage anther (before the phase nine), while there was no signal in other tissues. Because PARP-1 gene is strongly induced by genotoxins, this article also investigated the response of PARP-1 promoter to bleomycin and mitomycin. The results indicated that low-dosage genotoxins can highly induce the promoter, and this dosage has no obvious negative-effects on the growth of plants. Considering PARP-1 can not be induced by the other internal and external factors, it is very likely that this chemical-inducable promoter has a good prospect of application.