Transcriptomic insights into the regulatory networks of chilling-induced early flower in tobacco (Nicotiana tabacum L.)

ABSTRACT Appropriate timing of flowering is pivotal for tobacco, while chilling stress occurring at the seedling stage often undesirably leads to early flowering. However, the potential mechanism underlying chilling-induced early flowering remains unknown. Here, transcriptome sequencing was performed in tobacco with or without chilling at both seedling and budding stages. Chilling affected the expression of numerous genes at the seedling stage, while these dramatic expression changes were largely eliminated at the budding stage. A small number of genes related to metabolism, flower development, and stress tolerance continued to keep their altered expression patterns from the seedling stage to the budding stage. Many potential flowering-related genes involved in flowering pathways were identified and over half of them were differentially expressed. Functional analysis revealed that the down-regulation of NbXTH22 rendered tobacco less sensitive to chilling-induced early flowering. These results provide valuable resources for the investigation of flowering regulatory mechanisms and contribute to the genetic improvement of crops.