Identification of Transcription Factors of GmHPL Involved in Modulating Pathogen Stresses in Soybean

As an important branch of the lipoxygenase (LOX) metabolism pathway, hydroperoxide lyase (HPL) is involved in regulating plant development and defense responses. However, the upstream regulatory mechanism of HPL remains unclear in soybean. In the present study, by analyzing the upstream promoter region of the GmHPL gene, cis-elements such as MYB motifs, G-box motifs, ERE motifs and W-box motifs were predicted, which were related to the stress response. Yeast one-hybrid was employed and two transcription factors were identified, GmERF36 and GmILR3. The orthologs of ERF36 and ILR3 in Arabidopsis were involved in pathogen stress. A dual-luciferase reporter assay verified the yeast one-hybrid results and indicated that GmERF36 and GmILR3 suppressed the expression of the GmHPL protein. The qRT-PCR results indicated that GmHPL and GmERF36 initially displayed inverse expression patterns within 24 h after Colletotrichum truncatum treatment (GmERF36 was upregulated while GmHPL was downregulated); then, both of them were upregulated before decreasing. The results indicated that the response of GmHPL to pathogen stress partially depended on GmERF36. Our study gives rise to new insights into the upstream regulatory network of the GmHPL gene.