Microarray-based large scale detection of single feature polymorphism in Gossypium hirsutum L

Microarrays offer an opportunity to explore the functional sequence polymorphism among different cultivars of many crop plants. The Affymetrix microarray expression data of five genotypes of Gossypium hirsutum L. at six different fibre developmental stages was used to identify single feature polymorphisms (SFPs). The background corrected and quantile-normalized log2 intensity values of all probes of triplicate data of each cotton variety were subjected to SFPs call by using SAM procedure in R language software. We detected a total of 37,473 SFPs among six pair genotype combinations of two superior (JKC777 and JKC725) and three inferior (JKC703, JKC737 and JKC783) using the expression data. The 224 SFPs covering 51 genes were randomly selected from the dataset of all six fibre developmental stages of JKC777 and JKC703 for validation by sequencing on a capillary sequencer. Of these 224 SFPs, 132 were found to be polymorphic and 92 monomorphic which indicate that the SFP prediction from the expression data in the present study confirmed a ~58.92% of true SFPs. We further identified that most of the SFPs are associated with genes involved in fatty acid, flavonoid, auxin biosynthesis etc. indicating that these pathways significantly involved in fibre development.