Soil nematode community varies between rice cultivars but is not affected by transgenic Bt rice expressing Cry1Ab or Cry1Ab/Cry1Ac

Abstract

Insecticidal crystal (Cry) proteins produced by transgenic Bacillus thuringiensis (Bt) rice that enter the soil via root exudation and plant residues may be harmful to non-target soil organisms. We conducted a 3-year field investigation to determine if soil nematode abundance and diversity were affected by exposure to two transgenic Bt rice cultivars, compared to their non-transgenic near isolines. Near isolines were Kemingdao (KMD-Bt) expressing the single Cry1Ab gene and its non-Bt near isoline Xiushui-11 (XSD), as well as Huahui-1 (HH-Bt) expressing the fused Cry1Ab/Cry1Ac gene and its non-Bt near isoline Minghui-63 (MH). Nematode variables including community composition, abundance, trophic groups, and most of the common genera differed significantly between the rice cultivars. However, these nematode variables were similar under transgenic Bt rice and its non-Bt near isoline, although higher Shannon’s index value and Pielou’s index value were found in soils planted with Bt rice than the non-Bt near isoline. During this 3-year field study, gene modification (single Cry1Ab gene and fused Cry1Ab/Cry1Ac gene) supports a more uniform distribution of nematode species but had no effect on soil nematode abundance and community composition. We conclude that continuous cultivation of KMD-Bt and HH-Bt rice varieties for 3 years is not detrimental to soil nematode communities under field conditions.