Overexpression of the Wild Soybean R2R3-MYB Transcription Factor GsMYB15 Enhances Resistance to Salt Stress and Helicoverpa Armigera in Transgenic Arabidopsis

Abstract

Plant R2R3-MYB transcription factors (TFs) have been suggested to play crucial roles in the response to diverse abiotic and biotic stress factors but there is little molecular evidence of this role in soybean plants. In this work, we identified and functionally characterized an R2R3-MYB TF, namely, <i>GsMYB15</i>, from the wild soybean ED059. Protein and promoter sequence analysis indicated that <i>GsMYB15</i> is a typical R2R3-MYB TF and contains multiple stress-related <i>cis-</i>elements in the promoter region. <i>GsMYB15</i> is located in the nucleus and exhibits transcriptional activation activity. QPCR assays suggested that the expression of <i>GsMYB15</i> could be induced by NaCl, insect attacks and defense-related hormones (MeJA and SA). Furthermore, <i>GsMYB15</i> exhibited highest expression in pods compared to other tissues. Functional analysis of <i>GsMYB15</i> demonstrated that overexpression of <i>GsMYB15</i> could increase salt tolerance and enhance the resistance to <i>H. armigera larvae</i> in transgenic <i>Arabidopsis</i> plants. Moreover, overexpression of <i>GsMYB15</i> also affected the expression levels of salt stress- and defense-related genes in the transgenic plants. Feeding with transgenic <i>Arabidopsis</i> plant leaves could significantly suppress the expression levels of immunity-related genes in <i>H. armigera larvae</i>. Overexpression of <i>GsMYB15</i> also increased mesophyll cell levels in transgenic plants. Taken together, these results provide evidence that <i>GsMYB15</i> is a positive regulator of salt stress tolerance and insect resistance in transformed <i>Arabidopsis</i> plants.