Abstract：Abstract Late embryogenesis abundant protein (LEA) is a kind of cytoprotective protein accumulated under abiotic stress in plant. LEA gene family is the hot spot of stress research. Salvia miltiorrhiza is an important medicinal plant and its dry roots or rhizomes have been widely used as traditional Chinese medicine. Its yield and quality are easily affected by adversity. The objective of this study is to identify LEA proteins in S. miltiorrhiza and analyze the gene sequence, physical and chemical properties, tissue expression specificity and expression profile under different stress treatments. Based on S. miltiorrhiza genome and transcriptome database, SmLEA genes were identified and the physical and chemical properties were analyzed by bioinformatics methods. The phylogenetic tree, conservative motifs, gene structure and promoter region were analyzed by MEGA5.0, MEME, GSDS2.0 and BDGP bioinformatics tools, and the expression profile of SmLEA genes was analyzed by using the qRT-PCR and public RNA-seq databases. A total of 23 SmLEA genes were systematically identified and divided into 7 groups, SmLEA-1, SmLEA-2, SmLEA-3, SmLEA-4, SmLEA-5, SMP and Dehydrin, respectively. The theoretical of isoelectric points of SmLEAs ranged from 4.51 to 10.3 and most SmLEAs belonged to the highly hydrophilic protein. Prediction results showed that SmLEAs were distributed in different subcellular compartments, such as nucleus, mitochondrion, chloroplast, cytoplasm, and extracellular matrix. Obvious differences were observed in motif composition in genes among different groups. The gene structure was conserved and introns were relatively few. The promoter region contained a large number of MBS (MYB binding site), TGACG-motif, TCA-element, low temperature response (LTR), high temperature response element (HSE), GARE-motif, CGTCA-motif and abscisic acid responsive element (ABRE) abiotic stress response cis-element. The results of qRT-PCR showed that SmLEA genes expressed in root, stem, leaf and apical bud, with a higher expression level in root and stem. The expression of SmLEA genes in the seedlings of S. miltiorrhiza was tested after treatment by salt, dehydration, injury, high temperature and low temperature. It was found that the expression of most genes were up-regulated, of which SmLEA1-3, SmLEA4-2, SmLEA4-6, SmLEA7-2, SmLEA7-4 were significantly up-regulated in the 5 stress treatments. The results of digital gene expression profiles showed that after treatment with methyl Jasmonate (MeJA) and salicylic acid (SA), SmLEA genes were more than doubled in the expression of 9 genes and 2 genes respectively, indicating that SmLEA genes had a higher response to methyl jasmonate (MeJA). SmLEA proteins were highly conserved and the conserved motifs of different subgroups were specific. The promoter regions of SmLEA genes contained a large number of abiotic stress response cis-element. Most of the genes responded to salt, dehydration, injury, high temperature, low temperature stress, MeJA and SA hormone treatment, suggesting that the family genes played an important role in abiotic stress. This study analyzed the gene sequences, physicochemical properties, tissue expression specificity and expression levels of SmLEA family genes under different stress treatments, which provides the basic data for for further study of SmLEA family genes and the resistance mechanism and breeding new resistant varieties of S. miltiorrhiza.
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