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 occurs during the vegetative stage with drastic morphological and physiological changes. 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 and VRN1 near-isogenic lines (NILs) under controlled growth conditions, and leaf morphology under field growth conditions. Under controlled conditions, the results indicated that the timing of JA phase transition completion varied among spring varieties without association with VRN1 genotypes. All NILs underwent the JA phase transition at the same timing, and the expression levels of miR156 and miR172 were unrelated to VRN1 expressions during the vegetative stage. The field evaluation of leaf morphology revealed that the phase transition timing was consistent regardless of the sowing timings. These results suggested that the JA phase transition regulatory pathway and the vernalization regulator VRN1 are independent in wheat. 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.