Rhizosphere最新文献

Alternative solutions to chemical fertilizers that can enhance soil fertility, increase crop yield, promote sustainable agriculture and reduce harmful environmental impacts are urgently required. Microalgal bio-inoculants can improve soil fertility, plant growth and crop yield, yet the response of native soil microbiome to microalgal application remains largely unexplored. A pot experiment was conducted to assess the effects of microalgae (a consortium of cyanobacteria and green microalgae) inoculation on the growth and yield of chili plants, soil fertility and soil microbiome. Our results showed that microalgal inoculation significantly enhanced plant morphometric parameters and increased dehydrogenase activity (p < 0.05). Similarly, soil organic carbon, soil chlorophyll, total polysaccharides and nutrients such as carbon, nitrogen, phosphorus, potassium and manganese were also significantly (p < 0.05) enriched in microalgal treatment groups (50% and 100%) compared to the control. Results showed that microalgal inoculation increased the soil microbial diversity, with the richness being higher in treated soils than in control. Metagenomics analysis revealed a shift in bacterial and fungal community composition with firmicutes, chloroflexi, planctomycetes, proteobacteria, bacillariophyta, basidiomycota and glomeromycota dominating microalgal-treated soils, while actinobacteria, bacteroidetes, and streptomycota dominating control soils. The findings suggested that microalgal bio-inoculation can increase the diversity and composition of native soil microbiomes and enhance soil fertility, growth, and yield in chili plants.

This study aimed to examine whether and how an arbuscular mycorrhizal fungus, Paraglomus occultum, affected the growth performance, antioxidant enzyme defense system, and expression levels of fourteen plasma membrane intrinsic protein (PIP) genes of cucumber seedlings after five days of waterlogging. The fungal treatment significantly increased growth rate of plant height and stem diameter, root length, and root surface area under waterlogging. Inoculation with P. occultum significantly boosted superoxide dismutase, peroxidase, and catalase activities under waterlogging, enabling inoculated plants to maintain low levels of hydrogen peroxide and malondialdehyde. The waterlogging up-regulated the expression of more CsPIP genes in inoculated versus uninoculated plants. Interestingly, four of fourteen CsPIP genes were down-regulated under no stress by P. occultum, and seven were up-regulated under waterlogging, implying that inoculated plants actively responded to waterlogging stress by up-regulating the expression of CsPIP genes. This study confirmed that P. occultum increased waterlogging tolerance in cucumber plants, which was associated with enhanced antioxidant enzyme defense system and up-regulation of CsPIP genes.

Plant breeding strategies hold promising potential for enhancing plant-microbe interactions in the rhizosphere, thereby promoting disease resistance and sustainable agriculture. This review explores the role of plant breeding in shaping rhizosphere bacterial communities and modulating chemical crosstalk for disease resistance. It highlights the potential of strategic breeding to manipulate root exudation profiles and recruit beneficial bacteria that can confer resistance to pathogens. Additionally, the concept of vertical transmission of microbes from the rhizosphere to seeds is discussed, emphasizing its importance in transferring beneficial microbiota across plant generations. Studies demonstrate successful transmission of bacterial communities from the rhizosphere to seeds, with notable effects on plant health and disease suppression. Leveraging this knowledge, innovative approaches integrating desired rhizosphere microbiomes into plant breeding programs offer promising solutions for developing resilient plant varieties. These strategies involve transplanting rhizosphere soil from healthy plants to facilitate interactions between the genotype and microbiome, resulting in enhanced disease resistance. Therefore, strategic breeding for optimizing plant-microbe interactions presents a sustainable approach to improving agricultural productivity and resilience against pathogens.

Sesbania cannabina is a leguminous salt-tolerant plant that has been effectively used in saline-alkaline land restoration, and forms symbiotic interactions with various rhizobia to form nodules. Ensifer alkalisoli YIC4027, a rhizobium, was screened from S. cannabina root nodules and has significant host specificity. However, the mechanism underlying the symbiotic salt tolerance of S. cannabina -YIC4027, and strategies to enhance this tolerance remain poorly understood. In this study, the mechanism underlying the effect of YIC4027 on the salt tolerance of S. cannabina and the effect of straw biochar on the symbiotic nodulation of S. cannabina-YIC4027 under salt stress were analyzed using a vermiculite pot test. The results indicated that inoculation with YIC4027 markedly increased the biomass, chlorophyll content, photosynthetic rate, superoxide dismutase (SOD) activity and catalase (CAT) activity of S. cannabina under salt stress, while there was no obvious change in glutathione (GSH) or proline (PRO) content. The nitrogen supply and salt concentration are important regulators of YIC4027 nodulation. Salt stress reduced the nodulation efficiency of YIC4027 by 66.67%, and straw biochar application resulted in a 5-fold increase in nodulation efficiency of YIC4027. The present results further suggest that the combination of YIC4027 and straw biochar is an effective biological method for enhancing the effectiveness of S. cannabina in saline-alkali soil improvement.

It is commonly known that arbuscular mycorrhizal fungi (AMF) inoculation may modulate several soil health quality indicators. In contrast, their role in altering the rhizosphere to promote the biosynthesis of plant bioactive compounds is often disregarded. Thus, this short review aimed at selecting research papers on this topic and describing what has been done already. Overall, terpene compounds were the most examined compound group, with soil enzyme activity assays being the most applied. In total, five papers were chosen, but only two of them linked AMF-induced rhizospheric modulation to increase the production of secondary metabolites, highlighting the need to test more plant species and different isolates to select which changes in the rhizosphere are more dependent on mycorrhizal inoculation and whether these strongly explain an enhanced accumulation of phytochemicals in mycorrhizal plants.

Intraspecific plant interactions are crucial in terrestrial ecosystems, especially in artificially controlled ecosystems. Understanding plant root development can facilitate the manipulation of root traits to enhance the productivity and sustainability of agricultural and pastoral ecosystems. To date, most studies on interactions between the plants have focused on environmental factors or individual species; however, the lack of cross-species comparative analyses has resulted in a significant disparity in findings. In this study, we conducted a greenhouse experiment using five dominant species from alpine grasslands, including three legume species (Thermopsis lanceolata, Oxytropis ochrocephala, and Tibetia himalaica) and two grass species (Elymus nutans and Stipa aliena). Using single-plant cultivation as the control, we investigated the overall changes in plant biomass and root traits when two conspecific plants are grown together (intraspecifically). Simultaneously, we explored the differences in roots traits between the interaction and no-interaction zones. The results showed that, firstly, there was no significant difference in biomass and root traits of different zones when single-planted. But the impact of intraspecific interactions on neighboring plants exhibited significant species-specific. In terms of biomass and root traits (except for forks), E. nutans, T. lanceolata and T. himalaica responded significantly negatively to their neighbors. Whereas S. aliena and O. ochrocephala showed no significant changes and even positive responses. The overall trend of changes in the root zones, whether interactive or non-interactive, was consistent, either increasing or decreasing simultaneously, albeit to different extents. For instance, the difference between the interaction and no-interaction zones of T. lanceolata and O. ochrocephala was substantial, leading to allometric growth. Finally, our results showed poor correlations of physicochemical and nutrient factors with root traits in four of the five species, all except for E. nutans. Altogether, our findings confirmed that root trait variations resulting from intraspecific plant interactions are species-specific. These findings underscored the importance of species-specific in intraspecific plant interactions involving biological interactions among plants, which should be considered in future studies.

Sustainable agricultural systems play a crucial role in improving soil properties and enhancing crop yields. Particularly for soybean, a vital agricultural commodity, no-tillage (NT) and integrated crop-livestock (ICL) systems have been employed in tropical regions. Despite the recognized benefits of using NT and ICL, there is a significant knowledge gap regarding their impact on the rhizosphere microbiome of soybean. Therefore, this field study aimed to explore and compare the responses of the bacterial and archaeal communities within the soybean rhizosphere in both NT and ICL systems. To address this objective, in addition to sampling the soybean rhizosphere, we collected samples from the bulk soil in the NT area and the rhizospheres of grass (Urochloa brizantha) and corn (Zea mays L.) in the ICL system, covering the typical land use in this region. The results revealed distinct bacterial and archaeal communities in the soybean rhizosphere under NT and ICL. Specifically, the ICL system enriched the soybean rhizosphere with KD4_96 (score 3), Vicinamibacteraceae (score 3), Candidatus Nitrocosmicus (score 2.5), and Methylobacterium (score 2.5). In contrast, NT led to an enrichment of Solirubrobacter (score 3), Amycolatopsis (score 2.8), Sphingomonas (score 2.8), and Nitrososphaeraceae (score 2.5). Microbial community interactions exhibited greater complexity in the soybean rhizosphere under NT (676 nodes and 7095 edges). Notably, both bacterial and archaeal communities in the soybean rhizosphere under NT and ICL demonstrated potential functionality in nitrogen fixation. Thus, this study showed that NT and ICL promoted different responses of bacterial and archaeal communities within the soybean rhizosphere which, can influence the plant's performance.

The soil bacteria are diverse in nature both physiologically and phylogenetically with spatial variations within the soil microenvironments. Plant roots secrete organic substances called root exudates which benefit bacteria able to incorporate these. Subsequently, as the root grows, it changes the organic carbon status of adjacent bulk soil, stimulating growth of some of the resident bacteria. This growth induces a shift in the soil bacterial community and causes modifications in its metabolic activities. This nutrient infusion could also activate resting structures such as endospores to grow. We asked how the bulk soil microbial community responds when encountering root exudates and hypothesized that bacteria able to grow rapidly would become predominant upon introduction of root exudates. We added synthetic root exudate cocktail (Dietz et al., 2020) to the bulk soil from a wheat field on day 0 and day 1. We determined the aerobic culturable count on R2A, and Bacillus cereus sensu lato on Mannitol Egg Yolk Polymyxin agar, and bacterial community composition by sequencing the V3–V4 regions of the 16S rRNA genes on days 0, 1, 2, 3, 4, 6, 8, 10, 12 and 14 of incubation. Alpha diversity (Shannon) decreased and recovered partially, indicating a shift in species evenness while the Chao1 index remained the same, indicating constant species richness. Beta diversity shifted substantially over time. Rare fast-growing genera like Paenarthrobacter and Pseudarthrobacter increased upon REC addition, while slow growing genera like Bradyrhizobium were constant over time. Some key genera like Stenotrophobacter responded only after ceasing of REC addition. Certain fast-growing genera like Bacillus did not increase in population density. Collectively, these results indicate that the bulk soil community shifted significantly when exposed to REC, and after termination of REC, continued to undergo shifts. This presents the root environment with diverse bacteria known to benefit growth, such as Paenarthrobacter and rhizobia.

The environmental and consumer concerns about the cultivation approaches and safety of food products obtained through the application of chemical fertilizers and synthetic pesticides have paved towards the use of precision agriculture and organic/integrated farming approaches. These approaches could be dichotomized as the precision agriculture-enabled techniques involving improvement in the use efficiencies of the applied agri-inputs and the use of microbial biofertilizers which involves plant growth promotion and provision of essential nutrients to the growing crop plants. The use of nano-products/devices for agricultural applications have emerged as one among the precision agriculture strategies. The nanomaterial derived products/devices have already been aptly utilized for electronics, paint, cosmetics, and pharmaceutical applications. The use of these nano-products have led to movement of nano-components from both industrial and agricultural sources to find their way to soil and water bodies as their ultimate sink sites. The fate, dynamics, and ecological repercussions of the nano-scale contaminants in land and water niches are enigmatic and the short and long-term impacts are required to be researched. The elusive status of the impact of nanomaterials on a variety of microorganisms further limits the precise role played by the two components. Therefore, it is imperative to identify the bi- and tri-partite interactions of nanomaterials with microbes and plants. Published literature advocates that the NMs can alter plant growth, physiology, and metabolism, besides affecting the diversity and activity of soil microbial communities. The existing know-how on the interactions between plant microbes and nanomaterials, focusing on the outcomes and implications of these interactions has been explored in this manuscript.

Bipolaris sorokiniana infestation in wheat is highly susceptible to common root rot and leaf black spot diseases, leading to significant yield loss. The detrimental effects of chemical fungicides are evident. However, the development of new biological control methods that meet the requirements of environmentally friendly and sustainable agriculture is still underway. In this study, we screened and identified a bacterial strain, JK-1, which exhibited significant antagonistic effects against B. sorokiniana, as Bacillus velezensis. In the present study, the fermentation filtrate of the antagonist strain JK-1 was prepared and its inhibitory effect on B. sorokiniana was investigated. Treatment with 20% JK-1 culture filtrate (CF) resulted in a reduction of 65.8% in the dry weight of B. sorokiniana mycelium and a decrease of 93.3% in the spore germination rate. Scanning electron microscopy (SEM) and laser scanning confocal microscopy (LSCM) revealed that the CF of JK-1 caused significant damage to the integrity of the cell membrane of B. sorokiniana. Additionally, LSCM demonstrated that CF treatment led to increased DNA leakage and the accumulation of reactive oxygen species (ROS) in B. sorokiniana mycelial cells. Moreover, the disruption of the antioxidant defense system of B. sorokiniana by CF was demonstrated through the assessment of key antioxidant enzyme activities. The crude extract of the JK-1 CF was analyzed using liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) and was determined to contain the lipopeptide surfactin. B. velezensis JK-1 exhibited significant control effects in biocontrol experiments involving detached leaves and potting. Furthermore, the JK-1 CF was found to significantly promote the growth of wheat seedlings. These results indicate that B. velezensis JK-1 holds great potential as a strain for controlling wheat root rot and can provide a new approach to wheat management.