Overexpression of LoERF4 from Oriental Lily Enhances Root Growth and Salt Tolerance in Arabidopsis

ERF/AP2 is a family of transcription factors that plays a broad role in plant growth and development and in responses to various environmental stresses. In our previous studies, we found that the transcription factor LoERF4 indirectly induces the breaking of dormancy in lily bulbs by regulating its downstream gene, LoXTH23. To further investigate the function of LoERF4, we overexpressed it in Arabidopsis thaliana. Paraffin section analysis revealed that root cells in OE-LoERF4 transgenic Arabidopsis thaliana lines exhibited significantly longer average cell lengths compared to the wild type. In the overexpression lines, the expression of multiple modified genes, including AtXTHs and AtEXPAs was significantly upregulated, and these lines exhibited earlier lateral root emergence and a significant increase in primary root length. Under 100 mM sodium chloride treatment, the overexpression lines exhibited significantly higher numbers of lateral roots, true leaves, and primary root length compared with the wild type (WT). In the OE-LoERF4 line, antioxidant enzyme (SOD, POD, CAT) activity was enhanced, oxidative damage was reduced (decreased MDA content), and root survival rate was improved (as reflected by TTC reduction). This confirms that LoERF4 may promote root development in the overexpression line by positively regulating downstream AtXTHs and AtEXPAs, while simultaneously enhancing the salt tolerance of the overexpression line.