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Journal of Integrative Agriculture  2017, Vol. 16 Issue (07): 1624-1633    DOI: 10.1016/S2095-3119(16)61456-9
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Effects of soil salinity on rhizosphere soil microbes in transgenic Bt cotton fields
LUO Jun-yu1, 2*, ZHANG Shuai1*, ZHU Xiang-zhen1, LU Li-min1, WANG Chun-yi1, LI Chun-hua1, CUI Jin-jie1, ZHOU Zhi-guo2
1 State Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Sciences, Anyang 455000, P.R.China
2 College of Agriculture, Nanjing Agricultural University/Key Laboratory of Crop Physiology & Ecology in Southern China, Ministry of Agriculture, Nanjing 210095, P.R.China
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Abstract      With increased cultivation of transgenic Bacillus thuringiensis (Bt) cotton in the saline alkaline soil of China, assessments of transgenic crop biosafety have focused on the effects of soil salinity on rhizosphere microbes and Bt protein residues. In 2013 and 2014, investigations were conducted on the rhizosphere microbial biomass, soil enzyme activities and Bt protein contents of the soil under transgenic Bt cotton (variety GK19) and its parental non-transgenic cotton (Simian 3) cultivated at various salinity levels (1.15, 6.00 and 11.46 dS m−1). Under soil salinity stress, trace amounts of Bt proteins were observed in the Bt cotton GK19 rhizosphere soil, although the protein content increased with cotton growth and increased soil salinity levels. The populations of slight halophilic bacteria, phosphate solubilizing bacteria, ammonifying bacteria, nitrifying bacteria and denitrifying bacteria decreased with increased soil salinity in the Bt and non-Bt cotton rhizosphere soil, and the microbial biomass carbon, microbial respiration and soil catalase, urease and alkaline phosphatase activity also decreased. Correlation analyses showed that the increased Bt protein content in the Bt cotton rhizosphere soil may have been caused by the slower decomposition of soil microorganisms, which suggests that salinity was the main factor influencing the relevant activities of the soil microorganisms and indicates that Bt proteins had no clear adverse effects on the soil microorganisms. The results of this study may provide a theoretical basis for risk assessments of genetically modified cotton in saline alkaline soil.
Keywords:  soil salinity        Bt cotton        soil microorganisms        microbial biomass carbon        microbial respiration        soil enzyme activity        Bt protein  
Received: 02 June 2016   Accepted: 06 July 2017

This work was supported by the National Natural Science Foundation of China (31501253) and the Project for the Development of Genetically Modified Crops, Ministry of Agriculture, China (2016ZX08011-002).

Corresponding Authors:  Correspondence CUI Jin-jie, E-mail:; ZHOU Zhi-guo, E-mail:   
About author:  LUO Jun-yu, E-mail:;

Cite this article: 

LUO Jun-yu, ZHANG Shuai, ZHU Xiang-zhen, LU Li-min, WANG Chun-yi, LI Chun-hua, CUI Jin-jie, ZHOU Zhi-guo . 2017. Effects of soil salinity on rhizosphere soil microbes in transgenic Bt cotton fields. Journal of Integrative Agriculture, 16(07): 1624-1633.

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