Effect of cry1Ab Gene Transformation on the Microbial Mediated Decomposition of Rice Residues under Intensive Rice Cropping System

Abstract

Although genetically modified (GM) plants can offer many benefits, the planting of transgenic crops has raised a number of concerns, including the ecological impact of these plant residues on soil ecosystems. In this study, the effects of rice expressing the Bacillus thuringiensis Cry1Ab protein (Bt rice) on the residue decomposition processes were assessed in comparison with parental rice variety (non-Bt rice) under rapeseed-rice cropping system and surface or incorporated placement conditions. Bacterial and fungal communities associated with residue decomposition were studied by terminal restriction fragment length polymorphism (T-RFLP) method and additive main effects multiplicative interaction (AMMI) analysis model. After 276 days and residue decomposition in the field condition, bacterial and fungal communities associated with decomposition were strongly affected by the temporal factor which represented the grouping of T-RFLP fingerprint according to the time factor alone IPC 1. The placement effect on soil bacterial and fungal communities was also detected which represented the grouping of T-RFLP fingerprint alone IPC 2. Although some differences were found between Bt and non-Bt rice varieties in some special stages and placements, the impact of cry1Ab gene transformation on microbial mediated decomposition was lower than temporal and placement factors.