Genome-wide identification and mining of candidate genes against Sclerotinia sclerotiorum of WAK/WAKL gene family in snapdragon（Antirrhinum majus L.）

【Objective】To identify the gene family members of the cell wall-associated kinase(WAK) and WAK-like kinases(WAKL) of Antirrhinum majus L.,and explore the candidate genes against Sclerotinia sclerotiorum. This study provided a theoretical reference for further analysis of WAK/WAKL molecular regulatory mechanism of A. majus against S. sclerotiorum. 【Method】Using Arabidopsis thaliana L. WAK/WAKL family proteins as reference sequences,the WAK/WAKL gene family members were identified from the A. majus genome database by bioinformatics method,and their physicochemical properties,phylogeny,gene structure,conserved mods,cis-acting elements and collinear relationships were predicted. Transcriptome sequencing and real-time fluorescence quantitative PCR were used to analyze the expression patterns of the family genes involved in S. sclerotiorum resistance. 【Result】A total of 27 WAK/WAKL gene family members were identified from the A. majus genome,including 16 WAK genes(AmWAK1-AmWAK16) and 11 WAKL genes(AmWAKL1-AmWAKL11),encoding 615-1085 amino acids. The theoretical isoelectric point(p I) ranged from 4.94to 8.69,and the most proteins were acidic. The total mean hydrophilic index(GRAVY) of all proteins was less than 0,indicating that all proteins are hydrophilic proteins. Most of the subcellular proteins were located in the plasma membrane region of the cell,and a few were located in the extracellular,vacuole,Golgi apparatus and nucleus. There were 27 members of WAK/WAKL gene family distributed unevenly on 8 chromosomes of A. majus,and 7 pairs of collinear homologous genes with A. thaliana WAK/WAKL gene family. The gene promoter region contained cis-acting elements involved in defense and stress response,methyl jasmonate response and salicylic acid response. The susceptible variety Am1 and resistant variety Am6 were screened by inoculating the leaves of sclallodiscus in vitro. There were 12 WAK/WAKL family genes significantly differentially expressed(P<0.05) among the resistant materials,and the expression patterns of 9 genes were basically consistent with the transcriptome sequencing results. Of the nine genes,five(AmWAK7,AmWAKL2,AmWAKL8,AmWAK6 and AmWAK13) were highly expressed in the root,stem,and leaf tissues of A. majus,while the remaining four(AmWAK2,AmWAK8,AmWAK9 and AmWAK12) were largely unexpressed in the root,stem and leaf tissues.【Conclusion】Twenty-seven members of the WAK/WAKL gene family are screened,which have similar gene structure and protein functional domains. Among them,AmWAK6,AmWAK7,AmWAK13,AmWAKL2 and AmWAKL8 are key candidate genes for resistance to S. sclerotiorum,and have potential functions of mediating disease resistance.