Agronomic and Physiological Characteristics and Proteomic Expression in Near-isogenic Lines of Bt and Non-Bt Glandless Cotton

Agronomic and physiological traits and protein expression were compared between non-Bt glandless upland cotton variety-Zhong5629 and its Bt-transgenic near-isogenic lines differing in cryIAc gene. Results showed that the Bt isogenic line had higher plant height and rate of effective bolls, more internal bolls but lower yield, than the non-Bt line. The Bt isogenic line had lower chlorophyll content and transpiration rate relative to the non-Bt line, but had higher Chl a/b, F0 and Fm. Soluble protein content in the Bt isogenic line was significantly higher at boll setting stage (BSS) but lower at initial flowering stage (IFS) compared with the non-Bt line. The Bt isogenic line had significantly higher concentrations of Ca, Mg, Cu, Zn, Mn and Fe at IFS, and P and Cu at BSS, whereas it had lower in concentrations of P, K and B at IFS, and K, S, Zn and Fe at BSS. The Bt-isogenic line exhibited less malondialdehyde content at BSS and lower superoxide dismutase activity at IFS and BSS. Furthermore, proteomic analysis of the two NILs detected 20 differentially expressed proteins. The 4 up- regulated proteins in Bt vs non-Bt-isogenic line were attributed to signal transduction, photosynthetic carbon assimilation and defense response, whereas the 16 down- regulated proteins were attributed to signal transduction and protein metabolism.