Brassinosteroids (BRs) are a relatively new class of plant hormones that control important agronomic traits such as plant growth and architecture, seed yield and stress tolerance. BR and BR-related genes are thus strong targets for increasing crop yields, especially under suboptimal conditions. An additional effect of BR in cotton is on fibre development and elongation. This PhD project will explore brassinosteroid-regulated genes and pathways in cotton for their potential to increase yield through increased stress tolerance.