Research Article

Poor Homologous Synapsis 1 Interacts with Chromatin but Does Not Colocalise with ASYnapsis 1 during Early Meiosis in Bread Wheat

Figure 1

The PHS1 amino acid sequence is well conserved across plant species. (a) Alignment of TaPHS1 with four homologues shows high levels of sequence conservation. Amino acid positions that are conserved across at least three species, using the TaPHS1 amino acid sequence as the reference, are denoted by a ‘‘+’’ above. Four conserved regions were identified within the PHS1 protein and may represent functional domains: Region 1 (unbroken line), Region 2 (dashed line), Region 3 (dotted line), and Region 4 (dashed-dotted line). Oligopeptide repeat units (denoted by box) unique to TaPHS1 are also highlighted. Ta: Triticum aestivum PHS1, Sb: Sorghum bicolor PHS1, Zm: Zea mays PHS1, Os: Oryza sativa PHS1, and At: Arabidopsis thaliana PHS1-like (see Methods for accession numbers). (b) The evolutionary history of TaPHS1 was inferred using the Neighbor-Joining method [32]. (c) Three additional PHS1/PHS1-like sequences were obtained through Hidden Markov Model and MaxHom searches and were also assessed using phylogenetics. Vv: Vitis vinifera PHS1, Rc: Ricinus communis PHS1, and Pt: Populus trichocarpa PHS1. The reliability of the internal branches of the trees (b, c) was assessed with 10,000 bootstrap re-samplings [43], with the confidence probabilities shown next to the branches. The trees are drawn to scale, with branch lengths in the same units as those of the evolutionary distances used to infer the phylogenetic tree. The evolutionary distances were computed using the Poisson correction method [44] and are in the units of the number of amino acid substitutions per site. There were a total of 442 positions in the final datasets. Phylogenetic analyses were conducted in MEGA4 [33].