Journal of Environmental Biology

Effects of Transgenic Bt+CpTI cotton on the abundance and diversity of rhizosphere ammonia oxidizing bacteria and archaea

Lianhua Dong¹*, Ying Meng², Jing Wang¹ and Guoqing Sun³

 ¹National Institute of Metrology, Beijing-100 029, P.R.China

²Hubei Institute of Measurement and Testing Technology-430 223, Wuhan, P.R.China

³Chinese Academic of Agriculture Science, Beijing-100 081, P.R.China

*Corresponding Author E-mail: donglh@nim.ac.cn

Publication Data

Paper received:

09 February 2015

Revised received:

08 August 2015

Re-revised received:

03 December 2015

Accepted:

13 January 2016

Abstract

Genetically modified crops (GMCs) hold great promise for improving agricultural output, but at the same time present challenges in terms of environmental safety assessment. Ammonia oxidizers, including ammonia oxidizing bacteria (AOB) and archaea (AOA), are very important functional microbial groups in nitrogen cycle. The abundance and diversity of AOA and AOB in the rhizosphere of genetically modified cotton (SGK321) and non-GM cotton (SY321) across growth stages were investigated using real time quantitative PCR (qPCR) and terminal restriction fragment length polymorphism (T-RFLP). Results showed that cotton genotype had a significant effect on the change in abundance of AOA and AOB, as indicated by amoA copy number. Variations in AOB abundance in rhizosphere of SY321 differed from those in SGK321. The number of AOB in the rhizosphere of SY321 fluctuated considerably: It dramatically decreased from 1.2?10⁶ copies g^-1 dry soil to 3?10⁵ copies g^-1 dry soil during the flowering stage and then increased to 1.1?106 copies g-1 and 1.5?106 copies g-1 at the belling and boll opening stages, respectively. However, abundance of AOB in the rhizosphere of SGK321 was relatively stable during all the stages of growth. The effect of SGK321 and SY321 on AOA number was quite similar to that of AOB: AOA abundance in SGK321 increased smoothly from 1.0 ?10⁵ copies g^-1 dry soil to 1.4?10⁶ copies g^-1 dry soil during growth, but that in SY321 fluctuated. Correspondence analysis (CA), canonical CA (CCA), and partial CCA (pCCA) of T-RFLP profiles of AOA and AOB showed that AOB community changed across growth stages in both cotton genotypes, and cotton genotype was the most important factor affecting the AOA community. In conclusion, the current findings indicated no adverse effect of GM cotton on functional microorganisms.   

 Key words

Ammonium oxidizing archaea, Ammonium oxidizing bacteria, Bt+CpTI cotton, Genetically modified crop 

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