High-affinity K⁺ transporter (HAK) is one of the most important K⁺ transporter families in plants and plays an important role in plant K⁺ uptake and transport. To explore the biological functions and gene expression patterns of the HAK gene family members in sugar beet (Beta vulgaris), physicochemical properties, the gene structure, chromosomal location, phylogenetic evolution, conserved motifs, three-dimensional structure, interaction network, cis-acting elements of promoter of BvHAKs were predicted by bioinformatic analysis, and their expression levels in different tissues of sugar beet under salt stress were analyzed by qRT-PCR. A total of 10 BvHAK genes were identified in the sugar beet genome. They contained 8-10 exons and 7-9 introns. The average number of amino acids was 778.30, the average molecular weight was 88.31 kDa, and the isoelectric point was 5.38-9.41. The BvHAK proteins contained 11-14 transmembrane regions. BvHAK4, -5, -7 and -13 were localized on plasma membrane, while others were localized on tonoplast. Phylogenetic analysis showed that HAK in higher plants can be divided into five clusters, namely cluster Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ, among which the members of cluster Ⅱ can be divided into three subclusters, including Ⅱa, Ⅱb, and Ⅱc. The BvHAK gene family members were distributed in cluster Ⅰ-Ⅳ with 1, 6, 1, and 2 members, respectively. The promoter of BvHAK gene family mainly contained stress responsive elements, hormone responsive elements, and growth and development responsive elements. The expression pattern of the BvHAK genes were further analyzed in different tissues of sugar beet upon salt treatment, and found that 50 and 100 mmol/L NaCl significantly induced the expression of the BvHAK genes in both shoots and roots. High salt (150 mmol/L) treatment clearly down-regulated their expression levels in shoots, but not in roots. These results suggested that the BvHAK gene family plays important roles in the response of sugar beet to salt stress.
Beta vulgaris/genetics* ; Gene Expression Regulation, Plant ; Phylogeny ; Plant Roots ; Sugars/metabolism* ; Plant Proteins/metabolism*

We have recombined genes VvSUC11, VvSUC12 from Vitis vinifera L., and root-specific promoters of sweet potato storage protein gene from Ipomoea batatas L. Lam., named as SP1 and SP2. We have constructed a vector pCAMBIA2301-SP1- VvSUC11-SP2-VvSUC12 using pCAMBIA2301 as an original vector. VvSUC11 and VvSUC12 were under the control of root-specific promoters of sweet potato storage protein gene. We transformed the vector into KWS-9103 breeding line of Beta vulgaris L. with Agrobacterium-mediated transformation. We have established the optimal genetic transformation protocol of sugar beet as following: the explants pre-cultured for 4 days were immersed in Agrobacterium suspension of OD(600)=0.5, supplemented with 0.005% Silwet L-77, and followed by a 4-day culture on medium containing cefotaxime, then the buds were selected on medium containing kanamycin and cefotaxime. The percentage of kanamycin-resistant buds was as high as 42%. Results of PCR and RT-PCR proved that the target genes had integrated into sugar beet genome and expressed. It will lay a foundation for further studying their function in Beta vulgaris.
Agrobacterium ; genetics ; metabolism ; Beta vulgaris ; genetics ; Genetic Vectors ; Ipomoea batatas ; genetics ; Membrane Transport Proteins ; biosynthesis ; genetics ; physiology ; Plant Proteins ; biosynthesis ; genetics ; physiology ; Promoter Regions, Genetic ; Recombination, Genetic ; Transformation, Genetic ; Vitis ; genetics