Drought and Flowering Management by SlOST1-SlVOZ1 in Tomato

Author(s) and Institutions:

Leelyn Chong and Yingfang Zhu

State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences,

Henan University, Kaifeng 475001, China

Sanya Institute, Henan University, Sanya, 572025, China

Leelyn Chong and colleagues provide cues as to how plants accelerate their flowering when faced with adverse conditions like drought, using tomato as their model system.

Background: Flowering in tomato (Solanum lycopersicum) is a crucial developmental stage that can be hindered by environmental stresses such as drought. Prolonged exposure to drought at this stage can result in significant yield losses because drought stress threatens the growth and development of plants. Flowering has been reported as one of the mechanisms that plants utilize to respond to drought and hasten the production of seeds to ensure species survival.

Question: How does tomato know how to balance drought responses and flowering time? We investigated this question by examining the tomato ortholog to the kinase Open Stomata 1 (SlOST1), as OST1 is critical for abscisic acid (ABA) signaling, abiotic stress responses and regulation of stomatal movement in Arabidopsis and several other plant species, raising the possibility that OST1 may play a role in flowering.

Findings: We found that tomato SlOST1 not only positively regulates drought tolerance but also promotes flowering under drought stress conditions. We also discovered that SlOST1 promotes the stability and nuclear translocation of the NAC-type transcription factor VASCULAR PLANT ONE-ZINC FINGER 1 (SlVOZ1) via phosphorylation, which is further enhanced by ABA. In addition, we revealed that nucleus-localized SlVOZ1 can bind to the promoter of a major flowering gene SFT to modulate flowering. It was intriguing to discover the essential role of the SlOST1-SlVOZ1 module in balancing flowering and drought stress response in tomato.

Next steps: From previous and current studies, it is clear that OST1 is involved in various biological functions. The slost1 mutant plants of our study were smaller than the wild type, so we will be investigating the role of SlOST1 in tomato growth and development regulation next.

Reference: 

Leelyn Chong, Rui Xu, Pengcheng Huang, Pengcheng Guo, Mingku Zhu, Hai Du, Xiaoli Sun, Lixia Ku, Jian-Kang Zhu, Yingfang Zhu (2022). The tomato OST1-VOZ1 module regulates drought-mediated flowering. Plant Cell https://doi.org/10.1093/plcell/koac026