Analysis Of The Immune Function Of The Gene Tu939 Induced By Wheat Stripe Rust

Wheat(Triticum aestivum)is one of the most important food crops in China,and wheat rust is one of the major wheat diseases worldwide,which can cause serious reductions in wheat production.Wheat stripe rust is caused by Puccinia striiformis f.sp.tritici(Pst),which is characterized by rapid spread and wide damage area.Due to the frequent variation in the virulence of the stripe rust isolates,it is very easy to produce new physiological strains and cause the loss of disease resistance in existing varieties,also cause large-scale epidemic spread of stripe rust,which seriously affects the safety of grain supply in China.The most effective and environmentally friendly method to prevent and control wheat stripe rust is to breed and apply resistant varieties.The mining of novel wheat stripe rust resistance genes,their cloning and functional analysis are the keys for breeding disease resistanct wheat at present.This study mainly used Triticum urartu,the ancestor of the hexaploid wheat A genome,as the research material.A wheat stripe rust induced gene was obtained by homologous cloning,and its expression characteristics was analyzed.The disease resistance function of this gene was preliminarily analyzed using barley stripe mosaic virus-mediated gene silencing(BSMV-VIGS)technology,the main conclusions are as follows:According to the transcriptome analysis results of the Triticum urartu resistant accession Tu-51(PI428309)before and after inoculation with stripe rust,a receptor-like kinase gene whose expression is greatly up-regulated after inoculation with stripe rust was discovered.Referring to the sequence of Triticum urartu G1812,the receptor-like kinase gene was cloned and designated Tu939.The open reading frame(ORF)of Tu939 contains 2058 bp and encodes a protein of 685 amino acids,with the molecular weight of 74.75 k Da and the theoretical p I of 6.75.There is a signal peptide in Tu939,which is considered to be a hydrophobic protein.As L-type lectin receptor-like kinases(Lec RLKs),with an extracellular lectin structural domain,a transmembrane structural domain,and an intracellular kinase structural domain,Tu939 was localized in the cytoplasmic membrane after transient expression in wheat leaf cells and tobacco cells(Nicotiana benthamiana).Expression analysis of Tu939 gene in different tissues of Triticum urartu: It is expressed in roots,stems and leaves,the expression levels in leaves were significantly higher than those in roots and stems.Expression analysis of Tu939 gene after three exogenous hormones SA,JA and ABA treatment showed that: The expression of Tu939 was significantly upregulated under SA and JA treatments,but significantly down-regulated under ABA treatment.After infection with Pst CYR33 in the diseaseresistant accession Tu-51,the expression level of Tu939 gene was the highest one day post inoculation with stripe rust;In susceptible accession G1812,the expression level of Tu939 gene did not change significantly after inoculation with stripe rust.Using the Virus induced gene silencing(VIGS)system,the silencing of Tu939 was able to compromise the resistance of Tu-51 to stripe rust,and the spores of Pst CYR33 were able to grow rapidly on the gene silenced plants,which indicated that the L-type lectin receptor-like kinases Tu939 positively regulates the resistance of Tu-51 to stripe rust in wheat.After inoculation with wheat powdery mildew(Blumeria graminis f.sp.tritici,Bgt)the expression of Tu939 gene was significantly up-regulated.Using single-cell transient expression system,Tu939 was transiently overexpressed in single cells of powdery mildewsusceptible common wheat leaves,and the haustorium index was significantly reduced after inoculation with the wheat powdery mildew pathogen(Blumeria graminis f.sp.tritici,Bgt),indicating that Tu939 could potentiate the resistance to powdery mildew.The experiment verified that the L-type lectin-like receptor kinase Tu939 plays an important role in the immune response of wheat against various diseases.In conclusion,we obtained a disease-resistant lectin receptor-like protein kinase Tu939,which is localized in the plasma membrane and plays a positive regulatory role in wheat stripe rust resistance,and the protein may have broad-spectrum resistance to other pathogens,providing an excellent gene resource for wheat resistance breeding.