Comparison of chemical composition of different transgenic insect-resistant cotton seeds using Fourier transform infrared spectroscopy (FTIR)

The comparison of chemical composition of genetic modification (GM) crops to their conventional counterparts forms the basis of safety assessment process for GM crops. In this study, we used Fourier transform infrared spectroscopy (FTIR) to detect the chemical and conformational changes between transgenic cotton seeds and their non-transgenic counterparts. The assignment of absorption bands and comparison in band areas of four regions from original FTIR spectra indicated that the contents of the compounds did not differ significantly between transgenic cotton seeds and their non-transgenic counterparts (P > 0.05). The comparison of Fourier self-deconvolution (FSD) and after peak-smoothing spectra in the region between 2000 and 1000 cm -1 showed that the differences in band pattern can be observed obviously between transgenic cotton seeds and its counterpart, depending on the varieties. The changes in the protein profile of transgenic Bacillus thuringiensis (Bt) cotton seeds Z30 were significant, both in multi-peaks-fitted protein structures and its ratios, compared with non-transgenic cotton seeds Z16 (P < 0.05). However, transgenic Bt + cowpea trypsin inhibitor (CpTI) cotton seeds SGK321, did not show significant changes, in comparison with non-transgenic cotton seeds SY321. These results indicated that both the indigenous and exogenous proteins structural changes in genetically modified organism (GMO) are worth being detected in detail for research related to its’ safety assessment.