Genetic Map Construction and Functional Characterization of Genes within the Segregation Distortion Regions (SDRs) in the F2:3 Populations Derived from Wild Cotton Species of the D Genome

Abstract

Background: Segregation distortion (SD) is a phenomenon common among stable or segregating populations, and the principle behind it still puzzles many researchers. The F2:3 progenies developed from the wild cotton species of the D genomes were used to investigate the possible plant transcription factors within the segregation distortion regions (SDRs). A consensus map was developed between two maps from the four D genome, map A derived from an F2:3 progenies of Gossypium klotzschianum and G. davidsonii while Map B from G. thurberi and G. trilobum F2:3 generations. In each map 188 individual plants were used. Results: The consensus linkage map had 1492 markers across the 13 linkage groups; with a map size of 1467.445 cM and average marker distance of 1.037 0 cM. Chromosome D502 had the highest percentage of SD with 58.621% followed by Chromosome D507 with 47.887%. Six thousand and thirty eight genes were mined within the SDRs on chromosome D502 and D507 of the consensus map. Within chromosome D502 and D507, 2,308 and 3 730 genes were mined, respectively, and were found to belong to 1 117 domains out of which 622 domains were common across the two chromosomes. Moreover, the first 9 domains were members of the plant resistance genes (R genes), while Pkinase; Protein kinase domain (PF00069) was the dominant group with 188 genes. Further analysis on the dominant domains revealed that 287 miRNAs were found to target various genes, such as the gr-miR398, gra-miR5207, miR164a, miR164b, miR164c among others, which have been found to target top-ranked stress-responsive transcription factors such as NAC genes. Moreover, some of the stress responsive cis-regulatory elements were also detected. Furthermore, RNA profiling of the genes from the dominant family showed that higher numbers of genes were highly upregulated under salt and osmotic stress conditions, and in addition they were highly expressed at different stages of fiber development. Conclusion: The result obtained provided an indication of the important role of the SDRs in the evolution of significant genes in plants.