| Members of RAV(related to ABI3 and VP1)gene family mainly function in tissue/organ growth and TBL(Trichome Birefringence Like)gene family members are involved in trichome initiation in several plant species.However,function of TBL and RAV genes was not reported in G.hirsutum.In our research,we identified 102 TBL and 33 RAV genes from G.hirsutum.Phylogenetic tree classified TBL and RAV genes into three and four groups respectively.Gene structure analysis and protein motif distribution showed that GhTBLs and GhRAVs were highly conserved during evolution.Chromosomal location exhibited uneven distribution of GhTBL and GhRAV genes on chromosomes.Collinearity analysis of TBL genes indicated 136 orthologous/ paralogous gene pairs in G.hirsutum,while collinearity analysis of RAV genes exhibited 628 and 52 orthologous/ paralogous gene pairs in G.hirsutum and G.barbadense respectively.Ka/Ks values indicated that the GhTBLs and Gb RAVs underwent purifying selection.Promoter cis-elements of GhTBLs and GhRAVs were related to growth and development,seed specific regulation,light and stress responses.GhRAV genes(GhRAV4,GhRAV9 and GhRAV20)exhibited high expression for hormonal stresses(BL,JA and IAA).GhTBL genes(GhTBL7,GhTBL15,GhTBL21,GhTBL25,GhTBL45,GhTBL54,GhTBL67,GhTBL72,GhTBL77)exhibited positive and upregulated response under the exposure of cold,heat,Na Cl and PEG.Expression level of several GhRAV genes including GhRAV3,GhRAV4,GhRAV11,GhRAV18,GhRAV20 and GhRAV30 was high in roots and also GhRAV3 and GhRAV18 exhibited maximum expression in stem,demonstrating the function of these genes in root and stem development.However,GhTBL genes exhibited high expression during fiber development stages.Two GhTBL genes(GhTBL7 and GhTBL58)showed differential expression at 10 DPA fiber,as 10 DPA is fast fiber elongation stage and fiber elongation is very important stage of cotton fiber development.Next,we performed the subcellular localization of GhTBL7 and GhTBL58.Results revealed that GhTBL7 and GhTBL58 resides inside the cell membrane.Promoter GUS activity of GhTBL7 and GhTBL58 exhibited deep staining in roots.To further validate the role of these genes in cotton fiber elongation,we silenced these genes and observed significant reduction in the fiber length at 10 DPA. |
