The juvenile-to-adult phase transition in wheat is independent of the winter-spring growth habit regulated by VRN1

In plants, the juvenile-to-adult (JA) phase transition, also known as the vegetative phase change, occurs during the vegetative stage and involves drastic morphological and physiological changes. Its proper timing is crucial for plant survival and reproductive success. Common wheat (Triticum aestivum L.) has a molecular mechanism regulating the duration of vegetative growth in response to cold accumulation, and its sensitivity varies among varieties (winter-spring growth habit) predominantly due to VRN1 genotypes. However, the association of the growth habit with the JA phase transition remained unclear. Here, we investigated temporal changes in shoot apex and leaf morphology, and in the expression of the JA phase transition regulators miR156 and miR172, in winter and spring varieties under controlled growth conditions. The results indicated that the timing of the JA phase transition completion varied among varieties but was independent of VRN1 expression. The analysis using the VRN1 near-isogenic lines supported this conclusion. In addition, field measurements of leaf morphological changes across multiple environments suggested that varieties with a later JA phase transition exhibited greater phenotypic plasticity. This study provides further understanding of the regulatory mechanism underlying the JA phase transition in wheat and its potential utilization for breeding. HighlightThis study shows that the timing of the juvenile-to-adult phase transition in wheat is not affected by the expression of VRN1, the master regulator of vernalization.