GmWRKY81 Encoding a WRKY Transcription Factor Enhances Aluminum Tolerance in Soybean

Aluminum (Al) toxicity is an essential factor that adversely limits soybean ( (L.) Merr.) growth in acid soils. WRKY transcription factors play important roles in soybean responses to abiotic stresses. Here, was screened from genes that were differentially expressed under Al treatment in Al-tolerant soybean Baxi10 and Al-sensitive soybean Bendi2. We found that was significantly induced by 20 μM AlCl and upregulated by AlCl treatment for 2 h. In different tissues, the expression of was differentially induced. In 0-1 cm root tips, the expression of was induced to the highest level. The overexpression of in soybean resulted in higher relative root elongation, root weight, depth, root length, volume, number of root tips and peroxidase activity but lower root average diameter, malonaldehyde and H O contents, indicating enhanced Al tolerance. Moreover, RNA-seq identified 205 upregulated and 108 downregulated genes in transgenic lines. Fifteen of these genes that were differentially expressed in both AlCl -treated and -overexpressing soybean had the W-box element, which can bind to the upstream-conserved WRKY domain. Overall, the combined functional analysis indicates that may improve soybean Al tolerance by regulating downstream genes participating in Al transport, organic acid secretion and antioxidant reactions.