<i>OsABCG37</i> mediates root development and the stress response by modulating feruloylputrescine levels

Hydroxycinnamate amides (HCAAs) represent a major class of phenylpropanoid metabolites prevalent throughout the plant kingdom, garnering significant interest due to their roles in various biological processes. In this study, we identified a rice (Oryza sativa) ATP-binding cassette (ABC) transporter OsABCG37 that influences the level of feruloylputrescine, a HCAA compound. Using the CRISPR/Cas9 system to mutate OsABCG37, we observed impaired development of lateral roots and root hairs. Interestingly, the loss of OsABCG37 function disrupted the emergence of lateral roots. Expression pattern analysis employing a reporter gene system showed that OsABCG37 is predominantly expressed in epidermal cells of the primary root at sites of lateral root emergence as well as in lateral roots and root hairs. The corresponding protein was located in the plasma membrane. RNA sequencing and HPLC/MS experiments revealed that the OsABCG37 mutation led to reduced levels of intracellular feruloylputrescine and cell wall-associated ferulic acid, the latter serving as an indirect indicator of wall-bound feruloylputrescine, compared to the wild type. Supplementing with exogenous feruloylputrescine partially rescued the defects in lateral root and root hair development caused by the OsABCG37 mutation. In addition to defects in root development, mutants of OsABCG37 were sensitive to biotic and abiotic stresses. Collectively, our findings suggest a role for the OsABCG37 transporter in regulating root development and stress resistance by affecting feruloylputrescine levels.