Fatty Acid ABCG Transporter GhSTR1 Mediates Resistance to Verticillium dahliae and Fusarium oxysporum in Cotton

Verticillium wilt and Fusarium wilt cause significant losses in cotton (Gossypium hirsutum) production and have a significant economic impact. This study determined the functional role of GhSTR1, a member of the ABCG subfamily of ATP-binding cassette (ABC) transporters, that mediates cotton defense responses against various plant pathogens. We identified GhSTR1 as a homolog of STR1 from Medicago truncatula and highlighted its evolutionary conservation and potential role in plant defense mechanisms. Expression profiling revealed that GhSTR1 displays tissue-specific and spatiotemporal dynamics under stress conditions caused by Verticillium dahliae and Fusarium oxysporum. Functional validation using virus-induced gene silencing (VIGS) showed that silencing GhSTR1 improved disease resistance, resulting in milder symptoms, less vascular browning, and reduced fungal growth. Furthermore, the AtSTR1 loss-of-function mutant in Arabidopsis thaliana exhibited similar resistance phenotypes, highlighting the conserved regulatory role of STR1 in pathogen defense. In addition to its role in disease resistance, the mutation of AtSTR1 in Arabidopsis also enhanced the vegetative and reproductive growth of the plant, including increased root length, rosette leaf number, and plant height without compromising drought tolerance. These findings suggest that GhSTR1 mediates a trade-off between defense and growth, offering a potential target for optimizing both traits for crop improvement. This study identifies GhSTR1 as a key regulator of plant-pathogen interactions and growth dynamics, providing a foundation for developing durable strategies to enhance cotton's resistance and yield under biotic and abiotic stress conditions.