FveDAD2 negatively regulates branch crowns by affecting abscisic acid metabolism through FveHB7 in woodland strawberry

Abstract

Strigolactones (SLs) are a significant hormone in plant growth response, crucial for regulating branching. DECREASED APICAL DOMINANCE2 (DAD2) is a novel receptor of SL. Here, FveDAD2 in woodland strawberries (Fragaria vesca) as the receptor for SL was identified, and three FveDAD2-RNAi transgenic lines that exhibited the phenotype of multi-branched crowns and smaller fruits were obtained. Gene expression, phenotypic analysis, and yeast assays were used to investigate the function of FveDAD2 in regulating branch crowns in strawberries. Like the alpha/beta hydrolase D14, FveDAD2 interacts with FveSMXL7 and depends on SL. Furthermore, the yeast single-hybrid, GUS activity assay, and LUC assay results demonstrate that FveSMXL7 binds to the promoter of FveHB7 and repress its transcription. FveHB7, a homeobox transcription factor, negatively regulates the transcription of FveABA8OH1, which encodes the enzyme that catabolizes abscisic acid (ABA). ABA contents were reduced in the shoot tips of the FveDAD2-RNAi lines, while treating wide-type plants with 20 M ABA significantly suppressed the number of branches. In conclusion, we discovered a novel pathway of SL signaling to regulate branching through ABA. One-sentence summaryFveDAD2 negatively regulates branch crowns by affecting abscisic acid levels by interacting with FveSMXL7 to regulate the expression of FveABA8OH1 via the transcription factor FveHB7.