SbLOX3 modulates jasmonate-associated flavonoid accumulation, root growth, and drought-induced root hollow formation in Scutellaria baicalensis

Abstract

The hollowed root formation and 4′-deoxyflavone accumulation in Scutellaria baicalensis are associated with jasmonate (JAs) signaling, but the upstream regulators integrating these processes with drought tolerance remain unknown. This study investigated whether the 13-lipoxygenase gene SbLOX3 may act as a modulator. Transgenic plants overexpressing SbLOX3 or with RNAi suppression were exposed to polyethylene glycol-simulated and long-term soil drought stress. Metabolite profiling, gene expression analysis, root morphological measurements, and histological observations were conducted. Overexpression of SbLOX3 elevated JAs and 4′-deoxyflavone levels, enhanced root growth and drought tolerance, and induced precocious hollow development in roots under water deficit. In contrast, RNAi lines showed reduced JAs and flavonoid contents, impaired drought tolerance, and absence of hollow formation. SbLOX3 was strongly expressed in xylem, cambium, and phloem under drought. The results suggest that SbLOX3 is associated with a coordinated responseregulate to drought by promoting defensive flavonoid biosynthesis and morphological adaptation, thereby potentially contributing to the accumulation of measured flavonoids.