Effects of chitinase-transgenic (McChit1) tobacco on the rhizospheric microflora and enzyme activities of the purple soil

Abstract

In order to evaluate the bio-security of genetically modified (GM) plants in the purple soil, we carried out a pot experiment about rhizospheric microflora at different development stages of a chitinase-transgenic (McChit1) tobacco (T-Chit), a plasmid-transgenic tobacco (T-Vi), and a non-transgenic tobacco (Nt-X) that were grown in the same purple soil, and surveyed the growth of three tobaccos and the properties of soil (i.e. the dynamic changes of the cultivable rhizospheric bacteria and fungi, soil enzyme activity and pH). The results showed that, compared with Nt-X plant as a control, T-Chit and T-Vi at the stages of flowering and mature significantly decreased the number of cultivable rhizospheric bacteria, but at their stubble stage the bacteria number returned to the same levels. Moreover, there were no significant differences about the number of cultivable rhizospheric fungi and the ratio of fungi to bacteria (F/B) among three treatments. It was of interest that soil catalase activities of T-Chit and T-Vi were lower than that of Nt-X during the same period, and urease activities of T-Vi and T-Chit were also lower than that of Nt-X at the stages of budding and stubble. Protease activity and the biomass of tobacco, however, showed no significant difference. This indicated that 1-year-old transgenic tobacco plants (T-Vi and T-Chit) inhibited the catalase and urease activities of the purple soil. In conclusion, the results revealed that 1-year-old T-Chit and T-Vi plants were non-toxic to the colony-forming units of cultivable bacteria and fungi in the studied purple soil during tobacco growth.

Cultivation Effect of Chitinase-Transgenic Cotton on Functional Bacteria and Fungi in Rhizosphere and Bulk Soil

“…These results are in accordance with those of Wang, Shen (16), who reported that 1-year-old chitinase-transgenic (McChit1) tobacco (T-Chit) were non-toxic to the number of cultivable bacteria and fungi population in studied purple soil during tobacco growth.…”

“…Our knowledge of soil microbial diversity is limited in part because many groups of microbes are not cultivable in the laboratory conditions (14). Approximately 1% of the soil bacterial population can be cultured by standard laboratory practices (15, 16). The most knowledge on natural microbial community composition has been derived from indirect microbiological techniques.…”

Impact of transgenic AFPCHI (Cucumis melo L. Silver Light) fungal resistance melon on soil microbial communities and enzyme activities

“…Thus, transgenic plant products in the soil may alter ecological, physical and chemical environments like soil microbial population structure and quantity. Plant and soil associated microbial diversity are affected by not only plant species and newly introduced gene but also by environmental factors such as field area and sampling date (Donegan et al 1996;Wang et al 2013;Souza et al 2013). Little studies have been reported examining potential effects of transgenes on ecosystem in soil, the mineralization of crop residues, immobilization of nutrients and soil communities.…”

“…Little studies have been reported examining potential effects of transgenes on ecosystem in soil, the mineralization of crop residues, immobilization of nutrients and soil communities. Many field studies have displayed that the impacts on soil structure and microbial communities are transient and minor when compared to the factors caused by ecological and agronomic effects (Wang et al 2013;Wei Xiang et al 2006). Sources of soil enzymes including living and dead microbe, plant roots and soil animal residues play important functions in nutrient turnover and soil quality.…”

“…Arylsulphatases influence the hydrolysis of sulphate esters in soil and are secreted by microorganisms to the external environment against sulphur limitation (G. Shukla and A. Varma et al 2012). Previous reports displayed that transgenic crops could influence enzyme activities in rhizosphere soil (Wang et al 2013). Therefore, it is necessary to explore the effects of transgenic plants on rhizosphere soil enzyme activity when carrying out environmental safety risk assessments.…”