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 (<i>Gossypium hirsutum</i>) production and have a significant economic impact. This study determined the functional role of <i>GhSTR1</i>, a member of the ABCG subfamily of ATP-binding cassette (ABC) transporters, that mediates cotton defense responses against various plant pathogens. We identified <i>GhSTR1</i> as a homolog of <i>STR1</i> from <i>Medicago truncatula</i> and highlighted its evolutionary conservation and potential role in plant defense mechanisms. Expression profiling revealed that <i>GhSTR1</i> displays tissue-specific and spatiotemporal dynamics under stress conditions caused by <i>Verticillium dahliae</i> and <i>Fusarium oxysporum</i>. Functional validation using virus-induced gene silencing (VIGS) showed that silencing <i>GhSTR1</i> improved disease resistance, resulting in milder symptoms, less vascular browning, and reduced fungal growth. Furthermore, the <i>AtSTR1</i> loss-of-function mutant in <i>Arabidopsis thaliana</i> exhibited similar resistance phenotypes, highlighting the conserved regulatory role of <i>STR1</i> in pathogen defense. In addition to its role in disease resistance, the mutation of <i>AtSTR1</i> in <i>Arabidopsis</i> 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 <i>GhSTR1</i> mediates a trade-off between defense and growth, offering a potential target for optimizing both traits for crop improvement. This study identifies <i>GhSTR1</i> 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.