Genomic architecture and molecular regulation underlying heat-induced bolting in lettuce
TL;DR
Together, current evidence indicates that heat-induced bolting arises from coordinated environmental signal integration, reproductive commitment, and hormone-dependent stem growth rather than from a single linear thermosensory pathway.
Abstract
Premature bolting under elevated temperatures is a major constraint on lettuce production because it shortens the vegetative harvest period and reduces leaf quality. Bolting, floral transition, and flowering are closely connected but distinguishable processes that are regulated by overlapping genetic and environmental factors. Recent advances in lettuce genome assemblies, super-pangenomes, population resources, multi-omics analyses, and genome editing have enabled a more integrated understanding of this complex trait. This review summarizes the genomic architecture and natural variation associated with reproductive timing, the integration of temperature with photoperiodic and stress-responsive pathways, and the hormonal and metabolic changes that support inflorescence stem elongation. Particular attention is given to phytochrome-associated variation, heat-responsive transcription factors, LsSOC1, auxin and gibberellin signaling, and carbohydrate remodeling. We further discuss how these findings can inform genome editing, marker-assisted and genomic selection, and cultivation strategies. Together, current evidence indicates that heat-induced bolting arises from coordinated environmental signal integration, reproductive commitment, and hormone-dependent stem growth rather than from a single linear thermosensory pathway.