The Ph1-like gene in wheat shares some homology to Cdk2 in mammals, which regulates the progression of replication GDC-0941 through controlling chromatin decondensation during S phase. In wheat, the Ph1-like gene regulates premeiotic replication, chromatin condensation, transcription of the earliest meiotic gene, homologue pairing/ synapsis, resolution of incorrect pairing at pachytene and recombination. Recent studies have described that the Ph1 locus may affect replication through either an increment in the activation of origins and hence the rate of replication of the dispersed chromatin or, a delay in the initiation of heterochromatin replication in the absence of the Ph1 locus. Flow cytometry has become a useful method for studying the characteristics of eukaryotic cells, with applications in crop and horticultural science. Although flow cytometry has been crucial for chromosome sorting, allowing sequencing in species with large genomes such as wheat, other popular flow cytometric applications are the measurement of cellular DNA content for studies of ploidy, mostly in plants, and the identification of the cell distribution during the cell cycle. In fact, cell cycle-phase distribution of the DNA synthesis activity can be effectively determined by flow cytometry after isolation of nuclei. The four distinct phases can be recognised in a proliferating cell population by flow cytometry, although G2- and M-phase, which both have an identical DNA content, can not be discriminated based only on their differences in DNA content. Therefore cytogenetic approaches are required to determine whether chromosomes have entered meiosis by visualising chromosome condensation and pairing. In this work we aimed to further our knowledge of pre-meiotic and meiotic replication in wheat, focusing in the early meiosis stages using flow cytometry. To achieve this, we established a quick and user-friendly flow cytometry-based method to investigate replication during meiosis in wheat through the quantification of the amount of DNA in each meiotic stage. Flow cytometry has been revealed as a rapid and robust method to quantify the amount of DNA during the five sub-stages of early meiosis in wheat, and allowed a correlation between the amount of DNA and the level of replication at each stage during early meiosis in bread wheat. In addition, the effect of the Ph1 locus on the timing and on the rate of replication during early meiosis in wheat is also discussed. The cell cycle is a much studied process due to its importance in plant growth and development. The significance of replication during the cell cycle is critical to ensure proper chromosome association, recombination and segregation in meiosis, which is directly related to viability of gametes and therefore to fertility. This paper presents a simple and robust method for the determination of the synthesis of DNA during early meiosis by means of flow cytometric measurements in nuclei released from fixed wheat anthers. The structure of chromatin has been shown determinant for the initiation of replication. Moreover, homologous chromosomes usually replicate synchronously although there are some exceptions. In addition, replication of the chromatin has been shown temporary ordered in barley.