Analysis of GbRLK expression profiles in cotton seedlings in response to different stress treatments. Expression patterns of GbRLK at different time intervals in leaves under ABA (100 μM) treatment (a) for 0, 1, 2, 4, 6, 8, 10 and 12 h; drought (20% w/v PEG6000) (b), salinity stress (200 mM NaCl ) (c) and cold stress (4°C) (d) for 0, 1, 2, 4, 8, 12 and 24 h. The treatment was carried out by spraying the plants with 2 mM SA (e) and 100 μM MeJA (f) solution at 0, 2, 4, 6, 8, 10 and 12 h. Relative gene expression levels were determined using the 2^-ΔΔCT method. The CT (cycle threshold) values for both the target and internal control genes were means of three technical replicates. ΔCt = Ct target gene-Ct EF1α. ΔΔCT = (CTtarget -CTEF1α) xh - (CTtarget - CTEF1α) 0 h. (g) analysis of GbRLK expression profiles in different developmental stages and tissue. R: root, S: stem, L: leaf, C: cotyledons, 5-D, 10-D, 15-D represented the 5, 10, 15 days post anthesis of fiber, respectively; 0-D, 8-O, 15-O represented 0, 10, 15 days ovule, respectively. EF1a (At5g60390; EF-F/R; Additional file 1: Table S1) from cotton was used as an internal control for normalization of different cDNA samples. Error bars represent standard error of means based on three independent reactions.