Impact of PaGLK transgenic poplar on microbial community and soil enzyme activity in rhizosphere soil

Abstract

Rhizosphere microorganisms are essential parts in maintaining soil ecological functions. Reforestation using genetically modified trees might have great potential to enhance tree production in biotic and abiotic stress, however, their long-term impact on rhizosphere microorganisms is scant. In this study, we studied soil enzyme activities and composition of rhizosphere microorganisms in 2-year-old transgenic PaGLK overexpression (OE), repressed expression (RE) and wild-type (WT) poplar (P. alba × P.berlinensis). The root exudates of PaGLK transgenic poplar (P.alba × P. berlinensis) were analyzed by liquid chromatography-mass spectrometry (LC-MS). The results showed that there were significant difference for soil sucrase, urease, catalase, neutral protease and cellulase between the transgenic and WT lines at different growth periods. Alpha diversity analysis showed that bacterial community abundance and diversity for RE lines were significantly lower than WT (p < 0.05), while RE lines for fungi were significantly higher than WT lines. At the genus level, Burkholderia was the dominant group of rhizosphere bacterial community, and the relative abundance for RE was significantly higher than WT. Tomentella was the dominant group for fungi community. Serendipita for RE was significantly higher than WT and OE. Main metabolite contents of (S)-ACPA, geniposidic acid, agnuside, hydroquinone and pyranocoumarins were significantly different among transgenic lines. These results suggest that transgenic activities have effects on root exudates, rhizosphere soil enzyme activities and soil microbial community composition, but long term effects need to be further investigated.

Editing Metabolism, Sex, and Microbiome: How Can We Help Poplar Resist Pathogens?

“…When transgenic maize with a cloned Cry1Ah gene from B. thuringiensis was grown, no significant differences were found in the bacterial composition of the rhizosphere, but the metabolic profile was altered, with most of the altered metabolites being related to the metabolism of the plant itself rather than the pathways of the plant-bacteria relationship [363]. A similar result was obtained when growing the genetically modified potato variety Modena, tubers of which have altered starch content, but in this case, it is likely that the modulation of the microbial community was due to root exudate [364], which was also observed in an experiment on transgenic poplars [365]. Overall, a number of studies confirmed that rhizosphere composition can change only slightly, but the outcome still depends on which genes and metabolic pathways were involved [366][367][368].…”

Transcriptome and metabolome conjoint analysis revealed that PaGLK affects photosynthesis and composition of root exudates in poplar

“…Salas-González et al investigated the regulatory relationship between the root diffusion barriers in the endodermis and microbiota and found that genes controlling endodermal function in Arabidopsis thaliana contribute to the plant microbiome assembly [30]. Previous studies have shown signi cant differences in the activity of bacteria, fungi, and soil enzymes in the roots of transgenic poplar lines with overexpressed PaGLK, suppressed expression, and WT [21]. Furthermore, PaGLK gene expression alter the photosynthetic capacity of poplar [20].…”

“…The formation of a microenvironment by root secretions has signi cant implications, studies on root exudates in poplar is scarce. Our previous studies showed that suppression of PaGLK1 of Populus alba × P. Berolinensis reduces chlorophyll content and have effects on root exudates, rhizosphere soil enzyme activities and soil microbial community composition [20,21]. The root exudates primarily originate from plant photosynthesis.…”