An overview of low-oxygen sensing and flooding responses of tomato

Tomato (Solanum lycopersicum) is a globally significant and widely consumed vegetable crop. However, the productivity of tomato cultivation is increasingly threatened by flooding events, which are predicted to escalate in both frequency and severity due to climate change. During waterlogging, plants experience acute hypoxic stress, which can be lethal if prolonged. This review examines the mechanisms by which plants sense and signal low-oxygen stress, with a focus on the role of group VII ethylene response factors and the N-degron pathway, including their regulation. A comparative analysis of these low-oxygen signaling pathways between Arabidopsis and tomato reveals considerable conservation across species, although understudied in tomato. Furthermore, this review elucidates how hypoxia triggers various adaptation strategies in tomato. We highlight the physiological, morphological, metabolic, and hormonal responses, including modifications in plant transpiration and photosynthesis, the development of aerenchyma and adventitious roots, the induction of epinasty, and the reprogramming of energy metabolism. The review also provides insights into the hormonal signaling cascades that play a pivotal role in flooding stress responses. We aim to provide an in-depth understanding of how tomato plants deal with flooding-induced hypoxic stress. Additionally, we aim to provide insights that can be leveraged for breeding more flood-tolerant and climate-resilient tomato cultivars.