Functional Analysis Of NCA1 In The Regulation Of Programmed Cell Death Induced By H₂O₂ In Arabidopsis Thaliana

Programmed cell death?PCD?plays an important role in the response of plants to abiotic and biological stresses.The most representative PCD often occured in plants is hypersensitive response cell death during innate immunity and this process is often mediated by reactive oxygen species?ROS?.A large number of studies have reported that catalase2?CAT2?negatively regulates H₂O₂-induced PCD in Arabidopsis thaliana leaves.However,the regulation of H₂O₂-triggered PCD in plants is far from understood.Recent studies have shown that NCA1 as a molecular chaperone is essential to maintain intracellular CAT activity.Therefore,the first part of my thesis is to compare the association between NCA1,CAT2 and cell death by employing genetic,physiological and biochemical approaches.Tht nca1 mutant exhibited dramatically decreased intracellular CAT activity,redox state perturbation and growth inhibition comparable to those in cat2 mutants,whereas PCD was significantly compromised in nca1.Intriguingly,our results found that salicylic acid in nca1 was significantly accumulated but the salicylic acid signaling pathway including PR1 gene expression and PCD were not substantially activated.In addition,genetic evidence suggests that cat2 nca1 double mutants re-activate the salicylic acid signaling pathway and restore the phenotype of leaf cell death relative to nca1.In summary,we suggest that NCA1 modulate H₂O₂-induced PCD via regulating H₂O₂ homestasis and signaling.CAT1 and CAT3 were also present in Arabidopsis additional genome to CAT2,but their relative effects on H₂O₂-induced PCD were not well understood.For this,the second part of my thesis using CRISPR / Cas9 technology to build double knockout CAT1,CAT3 gene multi-target binary vector,and transformed into cat2 mutants.Our goal is to provide an important genetic material?cat1 cat2 cat3 mutants?for further analysis of the signal transduction mechanism of CAT regulated H₂O₂.