Direct Signaling Crosstalk Between Brassinosteroid and Abscisic Acid Regulates Root Growth Maintenance during Water Deficits in Soybean

Drought is the primary cause of yield loss in soybean, a major oil seed crop in the USA. It has been demonstrated that primary root maintains substantial elongation rates under severe water deficit conditions. However, The molecular mechanisms of root elongation under water stress remain unknown. We have developed an effective and efficient platform to infer and validate root elongation regulatory network in soybean. The platform includes a drought-related transcription factor library, a quantitative stress promoter analysis pipeline, a high throughput approach yeast-one-hybrid (Y1H) to measure direct interactions between promoter regions and transcription factors and a soybean hairy root transformation system for functional characterization of key regulators. Taking advantage of this platform, we discovered an interaction hub mediates direct signaling crosstalk between Brassinosteroids and Abscisic Acid to reveal root growth maintenance during water deficits. Identification of the key regulatory genes and elucidation of their regulatory networks of plant hormone interactions will greatly enhance our ability to develop effective strategies for enhancing crop drought resistance and productivity.