GmEIL4 enhances soybean (Glycine max) phosphorus efficiency by improving root system development

Phosphorus (P) deficiency seriously affects plant growth and development and ultimately limits the quality and yield of crops. Here, a new P efficiency-related major quantitative trait locus gene, GmEIL4 (encoding an ethylene-insensitive 3-like 1 protein), was cloned at qP2, which was identified by linkage analysis and genome-wide association study across four environments. Overexpressing GmEIL4 significantly improved the P uptake efficiency by increasing the number, length and surface area of lateral roots of hairy roots in transgenic soybeans, while interfering with GmEIL4 resulted in poor root phenotypic characteristics compared with the control plants under low P conditions. Interestingly, we found that GmEIL4 interacted with EIN3-binding F box protein 1 (GmEBF1), which may regulate the root response to low P stress. We conclude that the expression of GmEIL4 was induced by low-P stress and that overexpressing GmEIL4 improved P accumulation by regulating root elongation and architecture. Analysis of allele variation of GmEIL4 in 894 soybean accessions suggested that GmEIL4 is undergoing artificial selection during soybean evolution, which will benefit soybean production. Together, this study further elucidates how plants respond to low P stress by modifying root structure and provides insight into the great potential of GmEIL4 in crop P-efficient breeding.