Genome-wide Identification Of BvSnRK2 Family Genes In Sugar Beet And Their Functional Analysis

Sugar beet(Beta vulgaris L.),a biennial herbaceous plant of Chenopodiaceae,is the second largest source of sugar in the world and has important commercial value as a sugar crop.Due to climate change,sugar beet is adversely affected by the environment,resulting in low yield and low quality.Transgenic technology for genetic improvement of plants has become one of the fast and effective methods at present.Sucrose non-fermenting-1-related protein kinases 2(SnRK2)is plant specific and plays an important role in plant growth and development,resistance to biotic and abiotic stresses.A large number of previous reports have documented the progress of studies on the related functions of SnRK2 in different crops,but the study of SnRK2 in sugar beet is not clear.For that reason,in order to explore the characteristics of beet SnRK2 s family members and their functions in response to abiotic stress.In this paper,the SnRK2 s family of sugar beet was firstly analyzed by bioinformatics techniques.;Real-time quantitative PCR(qRT-PCR)was used to analyze the expression levels of BvSnRK2 s family members in beet roots and leaves under different treatments.Secondly,the full-length CDS sequences of BvSnRK2 s were cloned according to the known sequences,and the overexpression vectors pEG100-BvSnRK2 s were constructed.pEG100-BvSnRK2.1was introduced into tobacco plants by agrobacterium-mediated method to achieve the overexpression of BvSnRK2.1 gene.Finally,the function of transgenic plants was analyzed.The results are as follows:(1)A total of six SnRK2 s genes were obtained from beet by homology comparison and conserved domain screening of SnRK2 in Arabidopsis thaliana model plants,and the CDS length of BvSnRK2 ranged from 1008 bp(BvSnRK2.1)to 1095 bp(BvSnRK2.6).The isoelectric point(p I)ranges from 4.85 to 5.73,indicating that BvSnRK2 is acidic.The grand average of hydropathicity(GRAVY)is negative,indicating that BvSnRK2 s protein is hydrophilic.Phylogenetic analysis showed that SnRK2 was divided into Group Ⅰ(BvSnRK2.2and-3),Group Ⅱ(BvSnRK2.1 and-4)and Group Ⅲ(BvSnRK2.5 and-6)according to whether it was induced by ABA.Except BvSnRK2.4,which contained 8 exons,all the others contained9 exons.BvSnRK2 s exon/intron structure is relatively conserved.Analysis of cis-acting regulatory element showed that BvSnRK2 s contained hormone-related elements,light-responsive elements and stress-responsive elements,suggesting that BvSnRK2 s may be induced by different stresses.(2)qRT-PCR was used to analyze the expression of six BvSnRK2 s genes under drought and salt treatment.The results showed that BvSnRK2 s were expressed in beet leaves and roots;NaCl at 100 mmol/L induced up-regulated expression of most BvSnRK2 s genes in shoots and roots.Under drought treatment,the expression levels of 6 gene leaves were relatively high.The results showed that the expression patterns of BvSnRK2 s under different treatments were varied at different concentrations.(3)Primers for different BvSnRK2 s genes were designed according to known sequences of sugar beet,6 CDS sequences of BvSnRK2 s gene were cloned from sugar beet,and 6overexpression vectors pEG100-BvSnRK2.1 to pEG100-BvSnRK2.6 were successfully constructed.(4)Transgenic tobacco overexpressing BvSnRK2.1 in T1 generation was obtained by Agrobacterium-mediated method.Phenotypic statistics showed that roots of transgenic tobacco were longer than those of wild-type tobacco under drought and NaCl treatment.Physiological experiment results showed that the relative water content,malondialdehyde content and chlorophyll content of transgenic tobacco leaves increased,which improved the stress resistance of transgenic tobacco.In summary,bioinformatics analysis and expression pattern analysis of SnRK2 s gene family in sugar beet were conducted in this paper,by cloning the full length of six BvSnRK2 s genes from beet and functional analysis of transgenic tobacco,the function of the beet BvSnRK2.1 gene was preliminarily verified,it provides some theoretical basis for cultivating other crop varieties with stronger stress resistance.