Effect of transgenic alfalfa plants with introduced gene for Alfalfa Mosaic Virus coat protein on rhizosphere microbial community composition and physiological profile

Abstract

The aim of this study was to evaluate the effect of transgenic alfalfa (Medicago sativa L.) plants, in comparison to their non-transgenic counterpart, on the density and physiological profiles of aerobic bacteria in the rhizosphere. Plants of transgenic alfalfa expressing the AMVcp-s gene coding for Alfalfa Mosaic Virus coat protein were cultivated in a climatic chamber. Two methods were used to determine the microbial diversity in rhizospheres of transgenic plants. First, the cultivation-dependent plating method, based on the determination of the density of colony-forming bacteria, and second, a biochemical method using the Biolog TM system, based on the utilization of different carbon sources by soil microorganisms. Statistically significant differences in densities of rhizospheric bacteria between transgenic and non-transgenic alfalfa clones were observed in ammonifying bacteria (GTL4/404-1), cellulolytic bacteria (GTL4/404-1, GTL4/402-2, A5-3-3), rhizobial bacteria (GTL4/402-2), denitrifying bacteria (A5-3-3) and Azotobacter spp. (GTL4/402-2). The highest values of substrate utilization by microbial communities and average respiration of C-sources were determined in non-transgenic alfalfa plants of the isogenic line SE/22-GT2. Carbohydrates, carboxylic acids and amino-acids were the most utilized carbon substrates by both Gram-negative and Gram-positive bacteria. Both, the community metabolic diversity and the utilization of C-sources increased in all alfalfa lines with culture time and regardless of transgenic or non-transgenic nature of lines.

Sludge Biochar Amendment and Alfalfa Revegetation Improve Soil Physicochemical Properties and Increase Diversity of Soil Microbes in Soils from a Rare Earth Element Mining Wasteland

“…This indicated that alfalfa revegetation and sludge biochar amendment significantly increased soil microbial diversity in IAC mining wastelands ( p < 0.05), with an additive effect generated by their combined amendment. The results were in accordance with previous studies in biochar-enriched Terra preta soils [ 69 , 70 ] and alfalfa amended soils [ 71 , 72 ]. This increased microbial diversity might be due to the supply of a more comfortable habitats, many nutrients or mineralized organic matter from sludge biochar [ 6 , 73 ] and root exudates of alfalfa [ 74 ].…”

The impact of genetic modified Ma bamboo on soil microbiome

“…Some studies suggested that foreign gene products from GM plants negatively affect the abundance and diversity of soil microbial communities. Particularly, GM disease-resistant plants with antimicrobial products might inhibit the growth of beneficial microbe in soil ( Rasche et al, 2006 ; Faragová et al, 2011 ). However, more studies revealed that the cultivation of GM plants had no effect or minor effect on soil microbial communities ( Bruinsma et al, 2003 ; Guan et al, 2016 ).…”

“…Some studies have shown that GM plants reduce the soil microbial diversity ( Guan et al, 2016 ; Quemada, 2022 ). On the other hand, more studies illustrated that cultivation of GM plants had no or minor effects on soil microbial communities ( Faragová et al, 2011 ; Guan et al, 2016 ; Li et al, 2022 ; Quemada, 2022 ). Thus, there is no golden standard to judge the effect of GM plants on soil microbiota, and we need to evaluate the consequence in a plant-specific and gene-specific manner.…”

Impact of Transgenic Wheat with wheat yellow mosaic virus Resistance on Microbial Community Diversity and Enzyme Activity in Rhizosphere Soil

“…In a transgenic alfalfa study performed using the cultivation-dependent plating method, statistically significant differences in densities of rhizospheric bacteria between transgenic and non-transgenic alfalfa clones were observed for ammonifying bacteria, cellulolytic bacteria, rhizobial bacteria, denitrifying bacteria and Azotobacter spp. [46] . These results indicated that transgenic crops containing a viral gene conferring resistance to viral disease had little effect on soil microbial diversity (excluding a small number of studies) compared with non-transgenic crops.…”