Characterization of the gibberellic oxidase gene SdGA20ox1 in Sophora davidii (Franch.) skeels and interaction protein screening

Gibberellin 20-oxidases (<i>GA20oxs</i>) are multifunctional enzymes involved in regulating gibberellin (GA) biosynthesis and controlling plant growth. We identified and characterized the GA20ox1 gene in a plant height mutant of <i>Sophora davidii</i>, referred to as <i>SdGA20ox1</i>. This gene was expressed in root, stem, and leaf tissues of the adult <i>S. davidii</i> plant height mutant, with the highest expression observed in the stem. The expression of <i>SdGA20ox1</i> was regulated by various exogenous hormones. Overexpression of <i>SdGA20ox1</i> in Arabidopsis resulted in significant elongation of hypocotyl and root length in seedlings, earlier flowering, smaller leaves, reduced leaf chlorophyll content, lighter leaf color, a significant increase in adult plant height, and other phenotypes. Additionally, transgenic plants exhibited a substantial increase in biologically active endogenous GAs (GA1, GA3, and GA4) content, indicating that overexpression of <i>SdGA20ox1</i> accelerates plant growth and development. Using a yeast two-hybrid (Y2H) screen, we identified two SdGA20ox1-interacting proteins: the ethylene receptor <i>EIN4</i> (11430582) and the <i>rbcS</i> (11416005) protein. These interactions suggest a potential regulatory mechanism for <i>S. davidii</i> growth. Our findings provide new insights into the role of <i>SdGA20ox1</i> and its interacting proteins in regulating the growth and development of <i>S. davidii</i>.