Brief bioinformatics identification of cotton bZIP transcription factors family from Gossypium hirsutum, Gossypium arboreum and Gossypium raimondii

Cotton is an important commodity in the world economy. Transcription factors (TFs) are the key regulators in plant development and stress adaptation. Understanding interactions of TFs in cotton crop is important for enhancing stress tolerance and yield enhancement. Among plant TFs, bZIPs plays a major role in seed germination, flower development, biotic and abiotic stress response. Most of the bZIP proteins from cotton remains uncharacterized and can be utilized for crop improvement. In this study, we have carried out genome-wide identification and bioinformatics characterization of basic leucine zipper domain proteins (bZIPs) from cultivated cotton species Gossypium hirsutum along with two sub-genome species of allotetraploid cotton, Gossypium arboreum and Gossypium raimondii. A total of 228 bZIP genes of G. hirsutum, 91 bZIP genes of G. arboreum and 86 bZIP genes of G. raimondii were identified from CottonGen database. Cotton bZIP genes were annotated in standard pattern according to their match with Arabidopsis bZIPs. Multiple genes with similar bZIP designations were observed in cotton, linked to the gene duplication. Cotton bZIPs are distributed across all 13 chromosomes with varied density. Phylogenetic characterization of all three cotton species bZIPs classified them into 12 subfamilies, namely A, B, C, D, E, F, G, H, I, J, K and S and further into eight subgroups according to their predicted functional similarities, viz., A1, A2, A3, C1, C2, S1, S2 and S3. Subfamilies A and S are having maximum number of bZIP genes, subfamilies B, H, J and K are single-member families. Cotton bZIP protein functions were predicted from identified motifs and orthologs from varied species. Basic region leucine zipper (BRLZ) domain analysis of G. raimondii bZIPs revealed the presence of conserved basic region motif N-X7-R/K in almost all subfamily members, variants are GrbZIP62 with N-X7-I motif and GrbZIP76 with K-X7-R motif. Leucine heptad repeats motif, are also present in variant numbers from two to nine with leucine or other hydrophobic amino acid at designated position among 12 subfamily members. STRING protein interaction network analysis of G. raimondii bZIPs observed strong interaction between A and D, B and K, and C and S subfamily members. [GRPHICS]

Automated summary

bZIPs play important roles in seed germination, flower development, and stress response in cotton. The study identified uncharacterized bZIP proteins in cotton species, which can be utilized for crop improvement. Phylogenetic analysis classified cotton bZIPs into 12 subfamilies and predicted their functional similarities.