| RING proteins are crucial in plant response to biotic stresses and plant growth and development,but their precise roles and underlying mechanism remains largely unknown,especially in non-model plants such as pepper(Capsicum annuum)and other solanaceae.In the present study,the positive clone was cloned from the pepper normalized cDNA library.The full-length cDNA is 1386bp encoding polypeptide of 371 residues with a predicted molecule mass of 90.90KDa.The gene encode a protein which contain putative C3-H2-C3 type RING domain in this C-terminal region.The RING protein have 46%-72%sequence identity with preticted proteins including Vitis vinifera,Glycine max,Ricinus commuins and Arabidopsis CIP8 protein.So termed as CaRING2.The fusion CaRING2-GFP protein was contransformated into onion epidermal cells by using particle bombardment.The result showed that the protein coded by CaRING2 located in plasma membrane.The transient overexpression ofCaRING2 in pepper leaves induced typical HR mimicking cell death,showing dark typan blue staining and enhanced ion leakage and accompanying with accumulation of H2O2 showing dark DAB staining and upregulation of defense marker genes such as SA-responsive CaSAR82A,CaBPRl(for basic pathogenesis-related gene),CaP02(peroxidase;positive regulator of HR),CaHIRl(for hypersensitive-induced reaction gene)and downregulation gene,JA-responsive CaDEFl.The overexpression of CaRING2 in tobacco significantly decreased the susceptivity of tobacco to R.solanacearum inoculation,which was found to be correlated to the enhanced transcriptional expression of hypersensitive response marker genes including NtHSR203,NtHSR515 and SA-resposive gene NtPR2.By contrast,virus-induced gene silencing of CaRING2 enhanced the susceptibility of pepper plants to R.solanacearum inoculation.The results in this papper suggest that CaRING2 play a important role in pepper immunity. |
