Another mechanism of plant identification of bacterial infection is analyzed! The molecular mechanism of fatty acids produced by bacteria that stimulate plant immune response.

On January 10, 2020, the EMBO journal published a research paper entitled tyrosine phosphorylation of the lectin receptor like kinase lore regulations plant immunity by Liu Jun, researcher team of Institute of Microbiology, Chinese Academy of Sciences and center of excellence in biological interaction, reporting the molecular mechanism of plant immune response stimulated by fatty acids produced by bacteria.lipopolysaccharide (LPS) is an important component of the outer membrane of Gram-negative bacteria.in clinic, LPS is the main substance to stimulate human immunity and cause heat shock.in 1998, Bruce Beutler of Southwest Medical Center of the United States discovered the mammalian LPS receptor [1], and won the 2011 Nobel Prize in physiology or medicine.although many studies have confirmed that LPS can stimulate immune response in plants, its receptor and the mechanism of stimulating plant immune response are still unclear.ranf et al. Recently reported that lore, a lectin like receptor kinase on plant cell membrane, can recognize free 3-hydroxy fatty acids with medium carbon chain length during LPS synthesis, among which 3-oh-c10:0 of 10 carbons can significantly activate lore mediated plant defense responses [2,3].the research team of Liu Jun found that the receptor lore has serine / threonine and tyrosine dual protein kinase activities, and 3-oh-c10:0 treatment of plants can cause the phosphorylation of a tyrosine site on lore, which is necessary for lore to recognize 3-oh-c10:0.unlike protein kinases in animals, serine / threonine phosphorylation is common in plants, but tyrosine phosphorylation is rare.in order to further search for downstream signal components involved in lore recognition of 3-oh-c10:0, using immunoprecipitation and mass spectrometry techniques, our team found that three intracellular receptor kinases, pbl34, PbL35 and pbl36, were involved in downstream signal transmission after lore activation and could be phosphorylated by lore receptors.interestingly, the phosphorylation of tyrosine sites on lore is crucial for the phosphorylation of pbl34, PbL35 and pbl36.genetic evidence further supports that pbl34, PbL35 and pbl36 are key intracellular receptor like kinases downstream of lore, and their phosphorylation can activate the immune response of plants and realize defense against invasive pathogens such as Pseudomonas syringae.bacteria secrete some proteins to interfere with host resistance.this study found that Pseudomonas syringae can secrete a phosphatase during the infection process, which can directly bind to and target lore, remove the tyrosine site phosphorylation of lore receptor induced by 3-oh-c10:0, and then inhibit the lore mediated plant immunity and realize infection.therefore, the discovery further explains the process of identification and evolution between bacteria and plants, that is, bacteria inevitably produce 3-hydroxyfatty acids in the process of LPS synthesis, but they can secrete a protein to interfere with the defense process of plants, thus making Pseudomonas syringae a pathogenic bacterium with extensive host.figure: molecular mechanisms of plant recognition of fatty acids carried by pathogens and the response strategies of pathogens.plant receptor lore senses the intermediate chain length 3-hydroxyfatty acids carried by the pathogen, causing the phosphorylation of lore tyrosine Y600 site; the phosphorylated lore further transfers phosphorylated intracellular receptor like kinases, such as pbl34, and further activates the immune response.however, the bacteria can secrete the protein hopao1 to remove the phosphorylation of lorey600 and inhibit the immune response. medium chain length 3-hydroxyfatty acids are undoubtedly becoming an important class of substances to stimulate plant defense response, but many questions remain to be answered, such as whether they will be recognized by different plants? In addition, is there a mechanism to remove the phosphatase function of the pathogen in plants? The discovery of these problems will further enrich our understanding of the mechanism of plant resistance to bacterial invasion, and further promote the research progress of plant recognition of lipopolysaccharide and related molecules. since the establishment of the laboratory in the Institute of Microbiology, Chinese Academy of Sciences in 2013, Liu Jun's research group has been committed to studying the molecular mechanism of plant disease resistance and immunity. A series of important achievements have been made in the aspects of innate immunity mediated by lectin like receptor kinase in plants and the basic immunity of rice against Magnaporthe grisea infection, which were published in plant cell (2019) and plant respectively In the international mainstream journals such as physiology (2017), Plant Journal (2017), molecular plant microbe interaction (2016, 2017) and DNA research (2018). this study is another important achievement of Liu Jun's research group in the field of plant innate immunity mediated by lectin like receptor kinase. the doctoral students Luo Xuming and Liang Yingbo of Liu Jun's research group and Wu Wei, doctoral student of Fujian agriculture and Forestry University, are the co first authors of the paper, and researcher Liu Jun is the corresponding author of the paper. the project has been supported by national key R & D program, pilot project of Chinese Academy of Sciences and National Natural Science Foundation of China. 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