ScJAZ15-1 Attenuates Drought Tolerance and Promotes Flowering through Interaction with JA and Auxin Pathways in Sugarcane

Drought stress threatens sugarcane productivity. However, their tolerance mechanisms remain unclear. Here, we characterized the functional role of ScJAZ15-1, a sugarcane JAZ family gene, in drought tolerance. Transcript profiling revealed that ScJAZ15-1 is predominantly expressed in leaves and displays tissue-specific downregulation in roots under drought conditions. Overexpression of ScJAZ15-1 in transgenic plants resulted in early flowering and reduced drought tolerance, manifested by diminished proline accumulation, enhanced superoxide dismutase (SOD) and reduced peroxidase (POD) enzyme activity, and compromised stress resilience. Yeast two-hybrid assays revealed interactions with ScIAA1 and ScJAZ6, linking ScJAZ15-1 to auxin and jasmonic acid (JA) signaling. Transcriptomic analysis of ScJAZ15-1 overexpressing plants revealed repression of AtJAZ10 and induction of auxin-related genes associated with drought responses. Conversely, ScIAA1 overexpression enhanced drought tolerance. Together, our results identify ScJAZ15-1 as a negative regulator of drought tolerance in sugarcane, acting through JA and auxin crosstalk, and highlight its potential target for breeding drought-resistant sugarcane cultivars.