The Phenotypic and Developmental Impacts of Speed Vernalization on Hexaploid Wheat

Abstract

Winter wheat, (Triticum aestivum L.), requires prolonged exposure to cold to flower, a process called vernalization. Vernalization can slow down plant research and breeding programs. As a result, a speed vernalization protocol involving longer photoperiods was developed to accelerate breeding programs and it was shown to result in five generations of winter wheat annually. However, the underlying effects of this protocol on the development and the phenotype of winter wheat remained unknown. This study aimed to identify when the vegetative to reproductive transition occurs under speed vernalization and the phenotypic traits of speed vernalized wheat. Dissections of the apical meristems revealed that the wheat cultivar Claire fully transitioned from vegetative to reproductive in eight weeks of speed vernalization and speed breeding. Phenotyping also revealed that speed vernalization induced flowering early in wheat; however, the rapid development resulted in less spikelet formation. The study also revealed that the vernalization genes in winter wheat act differently under the speed vernalization conditions compared to regular vernalization conditions. Interestingly, the expression of the VRN1 gene increased after six weeks of speed vernalization and decreased at eight weeks under regular vernalization, indicating that the vernalization genes behave differently under speed vernalization.