Functional Analysis Of Arabidopsis Thaliana AtMLP In Plant Immunity

Plants have formed a complex and efficient immune system to resist the invasion of external pathogens during the long-term co-evolution process with pathogens.The active defense phenomenon that closes the stomata when guard cells sense pathogens is called stomatal immunity,which is an important part of plant immunity.Metallothionein is a low-molecular-weight,cysteine-rich,metal-binding protein that does not contain aromatic amino acids and is found in animals,plants,and microorganisms.It is unclear whether it regulates plant immunity.In this study,the resistance analysis of Arabidopsis metallothionein AtMLP in plant resistance pathogenic bacteria Pseudomonas syringae pv.tomato DC3000 was carried out,revealing the function of this gene in plant immunity.Bioinformatics analysis showed that Arabidopsis metallothionein AtMLP had the highest expression in guard cells.Tissue localization analysis further verified AtMLP expression in guard cells.Subcellular localization revealed that AtMLP gene was expressed on plasma membrane and nucleus.Screening for atmlp homozygous mutant and atmlp-oe overexpression was performed.After inoculation with Pst DC3000,the atmlp mutants leaves were found to be more severely yellower than the wild-type leaves and the atmlp isolates were higher,while atmlp-oe overexpressing plants have lighter yellow coloration than wild-type and the number of isolated bacteria is less than that of wild-type.No significant difference between mutant and wild type after injection of Pst DC3000 was seen.Therefore,AtMLP does not participate in resistance to Pst DC3000 through apoplast.On this basis,the stomatal opening experiment found out that the wild-type and atmlp-oe stomata were closed but the atmlp stomata were not closed after Pst DC3000 treatment,and at the same time,the accumulation of ROS in atmlp was reduced..This indicates that AtMLP regulates the stomatal immunity of Arabidopsis to Pst DC3000 by regulating the accumulation of ROS in guard cells.In addition,atmlp mutants inhibit ABA and Flg22 induced stomatal closure after treatment.Inoculation of Sclerotinia sclerotiorum and TMV revealed that AtMLP did not participate in Arabidopsis resistance to Sclerotinia sclerotiorum and TMV.To sum up,AtMLP is involved in the resistance of Arabidopsis thaliana to Pst DC3000,but not in the resistance of Arabidopsis thaliana to Sclerotinia sclerotiorum and TMV.The results revealed the function of Arabidopsis AtMLP in plant immunity.