Transcriptome Profiling Reveals Key Regulatory Networks for Age–Dependent Vernalization in Welsh Onion (Allium fistulosum L.)

Plants exhibit diverse pathways to regulate the timing of flowering. Some plant species require a vegetative phase before being able to perceive cold stimuli for the acceleration of flowering through vernalization. This research confirms the correlation between the vernalization process and seedling age in Welsh onions. Findings from two vernalization experiments conducted at different time intervals demonstrate that seedlings must reach a vegetative phase of at least 8 weeks to consistently respond to vernalization. Notably, 8-week-old seedlings subjected to 6 weeks of vernalization displayed the shortest time to bolting, with an average duration of 138.1 days. Transcriptome analysis led to the identification of genes homologous to those in <i>Arabidopsis thaliana</i> that regulate flowering. Specifically, <i>AfisC7G05578</i> (<i>CO</i>), <i>AfisC2G05881</i> (<i>AP1</i>), <i>AfisC1G07745</i> (<i>FT</i>), <i>AfisC1G06473</i> (<i>RAP2.7</i>), and <i>AfisC2G01843</i> (<i>VIM1</i>) were identified and suggested to have potential significance in age-dependent vernalization in Welsh onions. This study not only presents a rapid vernalization method for Welsh onions but also provides a molecular foundation for understanding the interplay between seedling age and vernalization.