Genome-Wide Identification Of The MES Gene Family In Brassica Napus And Gene Function Analysis Of BnMES9-4

Brassica napus is one of the most important oil crops in the world.Drought,salinity and pests seriously affect its growth,yield and quality.In A.thaliana,MES can hydrolyze MeSA to SA and improve stress resistance.At present,the function of MES genes family members in Brassica napus is rarely reported.In this study,the MES genes family members were identified at the whole genome level in Brassica napus,Brassica rapa and Brassica oleracea,and the physicochemical properties and expression patterns of MES family members in Brassica napus were analyzed.Meanwhile,the function of BnMES9-4 was preliminarily analyzed.The main results are as follows:1.Identification and bioinformatics analysis of MES genes familyFifty-one BnMES genes,27 BrMES genes and 29 BoMES genes were obtained through genome-wide identification.BnMES genes were distributed on 18 chromosomes,27 on chromosome A and 24 on chromosome C,respectively.The analysis of physicochemical properties of BnMES family members showed that the number of amino acids was between 113 and 569,and the molecular weight was between 20.02 and 63.21 k Da.The gene structure analysis showed that MES gene family had similar exon numbers in the same subfamily,the A and B subfamilies were mostly 3 – 4,and C subfamily was mostly 5.7 motifs are highly conserved in the BnMES gene family.At the same time,Ka / Ks showed that BnMES gene was purified and selected in evolution.The gene expression specificity and stress response process of BnMES family were analyzed.The result showed that BnMES genes contains multiple biotic and abiotic stress response elements and hormone response elements.RNA-seq analysis showed that most BnMES genes were expressed in different tissues and organs,and only BnMES13 and BnMES15 branches had low or no expression.BnMES1,BnMES2,BnMES9,BnMES14 and BnMES16 branches were highly expressed in most tissues.At the same time,several genes were induced by abiotic stress,such as BnMES4-5,BnMES9-3,and BnMES9-4.it was speculated that they played an important role in abiotic stresses.qRT-PCR results showed that ABA,PEG and NaCl induced the expression of BnMES4-5,BnMES9-3,BnMES9-4,BnMES16-1,BnMES16-2,BnMES16-4 and BnMES16-5.2.Study on gene function of BnMES9-4In this study,BnMES9-4 overexpression vector,subcellular localization vector and promoter vector were constructed.Subcellular localization results showed that BnMES9-4protein existed in nucleus and cell membrane.GUS staining showed that GUS had strong staining activity in different tissues and organs such as roots,stems and leaves,which indicated that BnMES9-4 was a non-specific expression gene and played a role in the whole life cycle of plants.Overexpression lines and wild-type were treated with stress in A.thaliana.Under the treatment of 300 m M Mannitol and 120 m M NaCl,the seed germination and root growth of the overexpression A.thaliana lines were inhibited,but the germination rate and root length of the overexpression lines were significantly higher than wild.The leaf water loss rate of overexpression lines was significantly lower than wild A.thaliana under drought stress.Compared with wild-type,the overexpression lines showed higher in Pro content,SA content,POD,CAT and SOD activities,and lower MDA and MeSA content under drought and salt stress.The expression of stress related pathway genes in overexpression lines was significantly higher than that in wild type under no stress treatment.Further analysis showed that the lesion area of BnMES9-4 overexpression lines was significantly lower than wild type at 24 h after S.sclerotiorum infection.It indicated that overexpression of BnMES9-4 enhanced stress tolerance in A.thaliana.