BIP130 enhances salt tolerance through modulation of ABA synthesis and scavenging ROS in rice (Oryza sativa L.)

Brassinosteroids (BRs) are plant steroidal phytohormones that play an important role in plant growth, stress responses, and adaptation. BIP130 is a BR-INSENSITIVE 1 (BRI1)-interacting protein, and BIP130 phosphorylation by OsMPK1 upregulates abscisic acid (ABA)-induced antioxidant defense in rice protoplasts. However, studies on BIP130-induced modulation of plant responses to salt stress are lacking. This study investigated the function of BIP130 in response to salt stress in transgenic rice (Oryza sativa L.). We assayed the relative BIP130 transcript levels in wild-type (WT) plants with NaCl treatment and observed the effects on scavenging reactive oxygen species (ROS) in transgenic plants. Changes in ABA content in transgenic plants were also analyzed. NaCl treatment upregulated relative transcript and protein levels of BIP130 in WT plants. The bip130 RNA interference (RNAi) rice mutants displayed a hypersensitive response to salt stress, while BIP130-overexpressing plants showed significant enhancement of salt tolerance, which was confirmed by changes in survival rates, antioxidant enzyme activities, H2O2 levels, and electrolyte leakage. RNA-sequencing analysis showed that BIP130 upregulates nine ABA-related genes (OsPSY2, OsNCED3, OsNCED4, OsCIPK6, OsCIPK16, OsCIPK31, OsEDL3, OsbZIP23, OsHVA22). ABA content significantly increased in BIP130-overexpressing and significantly decreased in bip130-RNAi plants. Therefore, BIP130 is involved in NaCl-induced antioxidant defense and enhances salt stress tolerance by modulating ABA biosynthesis and ROS scavenging in rice.