A reduced vernalization requirement is a key component of the early-bolting trait in globe artichoke (Cynara cardunculus var. scolymus)

Early bolting is a major breeding objective for globe artichoke (<i>Cynara cardunculus</i> var. <i>scolymus</i> L.). It has been suggested that globe artichoke bolting time is linked to a vernalization requirement, although environmental conditions under which vernalized plants and controls have been grown may not always allow for proper comparison. Here, we defined morphological markers to monitor the vegetative-to-reproductive phase transition at the shoot apex and linked these to expression changes of homologs of key Arabidopsis flowering regulators <i>SOC1</i>, <i>FUL</i>, and <i>AP1</i>. Importantly, we developed an experimental setup where control and vernalized plants grow under comparable conditions. These tools together allowed for comparison of the vegetative-to-reproductive phase transition between early- and late-bolting genotypes and how they respond to vernalization. Our results show that vernalization requirement is significantly lower in early-bolting genotypes, supporting the hypothesis that the early-bolting trait is at least partly underlain by alterations in the network controlling vernalization response.