Candidate Gene Identification of Flowering Time Genes in Cotton.

Flowering time control is critically important to all sexually reproducing angiosperms in both natural ecological and agronomic settings. Accordingly, there is much interest in defining the genes involved in the complex flowering-time network and how these respond to natural and artificial selection, the latter often entailing transitions in day-length responses. Here we describe a candidate gene analysis in the cotton genus Gossypium, which uses homologs from the well-described Arabidopsis flowering network to bioinformatically and phylogenetically identify orthologs in the published genome sequence from G. raimondii Ulbr., one of the two model diploid progenitors of the commercially important allopolyploid cottons, G. hirsutum L. and G. barbadense L. Presence and patterns of expression were evaluated from 13 aboveground tissues related to flowering for each of the candidate genes using allopolyploid G. hirsutum as a model. Furthermore, we use a comparative context to determine copy number variability of each key gene family across 10 published angiosperm genomes. Data suggest a pattern of repeated loss of duplicates following ancient whole-genome doubling events in diverse lineages. The data presented here provide a foundation for understanding both the parallel evolution of day-length neutrality in domesticated cottons and the flowering-time network, in general, in this important crop plant.