Genetically Modified Sugarcane Intercropping Soybean Impact on Rhizosphere Bacterial Communities and Co-occurrence Patterns

Impacts of AlaAT3 transgenic poplar on rhizosphere soil chemical properties, enzyme activity, bacterial community, and metabolites under two nitrogen conditions

Poplar stands as one of the primary afforestation trees globally. We successfully generated transgenic poplar trees characterized by enhanced biomass under identical nutrient conditions, through the overexpression of the pivotal nitrogen assimilation gene, pxAlaAT3. An environmental risk assessment was conducted for investigate the potential changes in rhizosphere soil associated with these overexpressing lines (OL). The results show that acid phosphatase activity was significantly altered under ammonium in OL compared to the wild-type control (WT), and a similar difference was observed for protease under nitrate. 16SrDNA sequencing indicated no significant divergence in rhizosphere soil microbial community diversity between WT and OL. Metabolomics analysis revealed that the OL caused minimal alterations in the metabolites of the rhizosphere soil, posing no potential harm to the environment. With these findings in mind, we anticipate that overexpressed plants will not adversely impact the surrounding soil environment.

DREB1 and DREB2 Genes in Garlic (Allium sativum L.): Genome-Wide Identification, Characterization, and Stress Response

Dehydration-responsive element-binding (DREB) transcription factors (TFs) of the A1 and A2 subfamilies involved in plant stress responses have not yet been reported in Allium species. In this study, we used bioinformatics and comparative transcriptomics to identify and characterize DREB A1 and A2 genes redundant in garlic (Allium sativum L.) and analyze their expression in A. sativum cultivars differing in the sensitivity to cold and Fusarium infection. Eight A1 (AsaDREB1.1-1.8) and eight A2 (AsaDREB2.1-2.8) genes were identified. AsaDREB1.1-1.8 genes located in tandem on chromosome 1 had similar expression patterns, suggesting functional redundancy. AsaDREB2.1-2.8 were scattered on different chromosomes and had organ- and genotype-specific expressions. AsaDREB1 and AsaDREB2 promoters contained 7 and 9 hormone- and stress-responsive cis-regulatory elements, respectively, and 13 sites associated with TF binding and plant development. In both Fusarium-resistant and -sensitive cultivars, fungal infection upregulated the AsaDREB1.1-1.5, 1.8, 2.2, 2.6, and 2.8 genes and downregulated AsaDREB2.5, but the magnitude of response depended on the infection susceptibility of the cultivar. Cold exposure strongly upregulated the AsaDREB1 genes, but downregulated most AsaDREB2 genes. Our results provide the foundation for further functional analysis of the DREB TFs in Allium crops and could contribute to the breeding of stress-tolerant varieties.

The impact of genetic modified Ma bamboo on soil microbiome

Evaluating the potential alteration of microbial communities is a vital step for biosafety of genetic modified plants. Recently, we have produced genetic modified Ma bamboo with increased cold and drought tolerance by anthocyanin accumulation. In this work, we aim to study the potential effects on microbial communities in rhizosphere soils during the cultivation of genetic modified bamboo. Rhizosphere and surrounding soil were collected at 3-month post-transplant. The amplicon (16S rDNA and ITS1) were sequenced for analysis of bacterial and fungal communities. Multiple software and database (Picrust2, FAPROTAX and FUNGulid) were applied to predict and compare the microbial functions involving basic metabolisms, nitrogen usage and presence of plant pathogens. There were no substantial change of the structure and abundance of rhizosphere soil microbial communities between genetic modified and wild type bamboo. For the surrounding soil, the bacterial biota α-diversity increased (chao1: 1,001 ± 80-1,276 ± 84, observed species: 787 ± 52-1,194 ± 137, PD whole tree: 75 ± 4-117 ± 18) and fungal biota α-diversity decreased (chao1: 187 ± 18-145 ± 10) in samples of genetic modified bamboo compared to those of wild type bamboo. The microbiota predicted functions did not change or had no negative alteration between genetic modified and wild type bamboo, in both rhizosphere and surrounding soils. As a conclusion, the growth of genetic modified bamboo had no substantial change on rhizosphere soil microbial communities, while minor alteration on bamboo surrounding soil microbial communities with no harmful effects. Moreover, the genetic modified bamboo had no negative effect on the predicted functions of microbiota in soil.

Maize intercropping enriches plant growth-promoting rhizobacteria and promotes both the growth and volatile oil concentration of Atractylodes lancea

In the Atractylodes lancea (A. lancea)-maize intercropping system, maize can promote the growth of A. lancea, but it is unclear whether this constitutes an aboveground or belowground process. In this study, we investigated the mechanisms of the root system interaction between A. lancea and maize using three different barrier conditions: no barrier (AI), nylon barrier (AN), and plastic barrier (AP) systems. The biomass, volatile oil concentration, physicochemical properties of the soil, and rhizosphere microorganisms of the A. lancea plant were determined. The results showed that (1) the A. lancea - maize intercropping system could promote the growth of A. lancea and its accumulation of volatile oils; (2) a comparison of the CK, AI, and AP treatments revealed that it was the above-ground effect of maize specifically that promoted the accumulation of both atractylon and atractylodin within the volatile oils of A. lancea, but inhibited the accumulation of hinesol and β-eudesmol; (3) in comparing the soil physicochemical properties of each treatment group, intercropping maize acidified the root soil of A. lancea, changed its root soil physicochemical properties, and increased the abundance of the acidic rhizosphere microbes of A. lancea at the phylum level; (4) in an analysis of rhizosphere microbial communities of A. lancea under different barrier systems, intercropping was found to promote plant growth-promoting rhizobacteria (PGPR) enrichment, including Streptomyces, Bradyrhizobium, Candidatus Solibacter, Gemmatirosa, and Pseudolabrys, and the biomass of A. lancea was significantly influenced by PGPR. In summary, we found that the rhizosphere soil of A. lancea was acidified in intercropping with maize, causing the accumulation of PGPR, which was beneficial to the growth of A. lancea.