Functional activation of a novel R2R3-MYB protein gene, <i>GmMYB68</i>, confers salt-alkali resistance in soybean (<i>Glycine max</i> L.)

Abstract

Soil salinity significantly reduces soybean (<i>Glycine max</i> L.) production worldwide. Plants resistance to stress conditions is a complex characteristic regulated by multiple signaling pathways. The v-Myb avian myeloblastosis viral oncogene homolog (MYB) transcription factor (TF) plays a crucial role in plant development, secondary metabolism, and abiotic stress responses. <i>GmMYB68-</i>overexpression and RNA interference (RNAi) lines were established for examining the function of <i>G. max GmMYB68</i> in plant responses to abiotic stresses. The predicted amino acid sequence of <i>GmMYB68</i> was similar to that of R2R3-MYB proteins. Quantitative real-time PCR analysis revealed that <i>GmMYB68</i> expression varied in response to abiotic stresses. <i>GmMYB68</i>-overexpression lines showed enhanced resistance to salt and alkali stresses and their osmotic adjustment and photosynthetic rates were also stronger than that of <i>GmMYB68-</i>RNAi and wild type plants. Although wild type and transgenic plants showed no significant differences in agronomic traits under normal conditions, the overexpression of <i>GmMYB68</i> increased grain number and 100-grain weights under salt stress. Our study identified a valuable TF associated with stress response in soybean, as its overexpression might help improve salt and alkali tolerance in soybean and other crops.