Analysis Of The Function And Mechanism Of Catalase In The Growth And Development In Arabidopsis Thaniala

Unfavorable environmental stresses such as high temperature,cold,drought,salinity,ultraviolet light,ozone stress,and pathogen infection can destroy the intracellular metabolic balance,leading to a large accumulation of reactive oxygen species in plant cells,thereby enhancing oxidative stress.Among them,H₂O₂ is the main reactive oxygen molecule,and catalase is the key enzyme to remove this molecule.In Arabidopsis,catalase is composed of proteins encoded by three genes（CAT1,CAT2and CAT3）,but are they All involved in the metabolism of H₂O₂ is not very clear.In this study,genetics,biochemistry and transcriptomics were used to analyze the effects of all catalase gene mutations on the growth,development,and physiology and biochemistry of Arabidopsis mutants.The specific research results are as follows:1.Compared with Col-0,cat1-2 cat2-1 cat3-1 mutants showed retarded leaf growth and root development.The results of measuring the fresh weight of rosette leaves showed that the fresh weight of cat1-2 cat2-1 cat3-1 was significantly reduced,the growth of the main root was inhibited and the number of lateral roots was drastically reduced.Moreover,cat1-2 cat2-1 cat3-1 mutant suppressed the emergence stage of lateral root primordium.Compared with Col-0,almost no catalase activity was detected in cat1-2 cat2-1 cat3-1 mutant;in addition,total glutathione and oxidized form in cat1-2 cat2-1 cat3-1 The content of glutathione is significantly increased.These results indicate that all catalase genes are involved in the metabolism of H₂O₂,thereby controlling the induction of oxidative stress.2.In addition,obvious programmed cell death occurred in the leaves,and the free salicylic acid（SA）and total SA content increased significantly.The mutation of SA synthesis key gene ICS1 completely blocked the cell death phenomenon of triglobulin cat1-2 cat2-1 cat3-1.This genetic evidence further proves the cell death and salicylic acid accumulation induced by cat1-2 cat2-1 cat3-1 mutation.related.3.Construct e YFP-CAT1 in cat1-2 cat2-1 cat3-1,e YFP-CAT2 in cat1-2 cat2-1 cat3-1 and e YFP-CAT3 in cat1-2 cat2-1 cat3-1 transgenic plants,these The transgenic plants reverted to the cat1-2 cat2-1 cat3-1 phenotype to varying degrees,and reduced the cell death of the leaves.And compared with cat1-2 cat2-1 cat3-1 mutant,the catalase activity of transgenic plants is also higher up-regulated.4.Using transcriptome sequencing technology to analyze the differential gene expression of Col-0 and cat1-2 cat2-1 cat3-1.The results showed that in cat1-2 cat2-1cat3-1,most of 303 ROS-responsive genes,48 SA synthesis and signal pathway related genes,and 38 immune-related genes were significantly induced to express,while the expression of 40 genes related to the photosynthesis process was down-regulated,which is similar to the phenotypic analysis of cat1-2 cat2-1 cat3-1 Unanimous.To sum up,due to the mutation of all catalase genes,the H₂O₂ level in the plant is significantly increased,and the oxidative stress is further enhanced,which induces the synthesis and accumulation of SA,activates the immune defense response that depends on SA,and leads to the appearance of cells in the leaves.The phenomenon of programmed death,and reduce the number of lateral roots by inhibiting the appearance of lateral root primordia.