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Nutrient efficiency can precisely synergize crop yield, resource efficiency and environmental protection, and become a golden key to crack the sustainable development problem. It is of great significance to propose a new theoretical system to substantially improve nutrient use efficiency. The cover image shows a new proposed academic theory of “Rhizobiont”, which includes plants, roots, rhizosphere, hypersphere, and their associated microbes. The root system, as the main orga [Detail] ...
Download coverPlant roots are crucial for nitrogen uptake. To efficiently acquire N, root system architecture (RSA), which includes the length and quantity of primary roots, lateral roots and root hairs, is dynamically regulated by the surrounding N status. For crops, an ideotype RSA characterized by enhanced plasticity to meet various N demands under fluctuating N conditions is fundamental for high N utilization and subsequent yield. Therefore, exploring the genetic basis of N-dependent RSA, especially in crops, is of great significance. This review summarizes how plants sense both local and systemic N signals and transduce them to downstream pathways. Additionally, it presents the current understanding of genetic basis of N-dependent root plasticity in Arabidopsis and major crops. Also, to fully understand the mechanisms underlying N-dependent root morphogenesis and effectively identify loci associated with an ideotype RSA in crops, more attention should be paid to non-destructive, in situ phenotyping of root traits, cell-type-specific exploration of gene functions, and crosstalk between root architecture, environment and management in the future.
Natural plant roots enrich a diverse array of soil microbes, collectively known as the root microbiota. This microbiota interacts synergistically with plants, modulating various physiological processes, including nutrient utilization, which influences plant growth and health. Environmental nutrient conditions and plant nutrient-related genes have been reported to regulate the composition of the root microbiota. Innovative analytical methods, such as microbiome genome- and microbiome-wide association studies, have advanced understanding of the relationships between plants and root microbiota. These methods systematically reveal the interactions between root microbiota and plant nutrient utilization, providing a theoretical foundation for applying root microbiota in agriculture.
Beneficial root-microbiome interactions offer enormous potential to improve crop performance and stress tolerance. Domestication and improvement reduced the genetic diversity of crops and reshaped their phenotypic traits and their associated microbiome structure and function. However, understanding of the genetic and physiological mechanisms how domestication and improvement modulated root function, microbiome assembly and even co-selective patterns remains largely elusive. This review summarizes the current status of how crop domestication and improvement (heterosis) affected root characteristics and their associated microbiome structure and function. Also, it assesses potential mechanisms how crop domestication and improvement reshaped root-microbiome association through gene regulation, root structure and function and root exudate features. A hypothetical strategy is proposed that entangles crop genetics and abiotic interactions with beneficial microbiomes to mitigate the effects of global climate change on crop performance. A comprehensive understanding of the role of crop domestication and improvement in root-associated microbiome interaction will advance future breeding efforts and agricultural management.
Interplant communication is of vital importance for plant performance in natural environments. Mycorrhizal fungi have emerged as key contributors to the below ground communication between plants. These mutualistic fungi form connections between the roots of plants via their hyphae, known as common mycorrhizal networks (CMNs). These hyphal networks are thought to be important ways for the exchange of signals between plants. This paper reviews the evidence for CMN-based transfer of semiochemicals between plants upon exposure to pathogen infection, herbivory or mechanical damage. Potential transport routes are explored, asking whether the fungi can actively contribute to the distribution of such signals within the network and discussing potential drivers for signal exchange. It is concluded that identification of the signals that are exchanged remains an important challenge for the future.
To efficiently obtain P from soil, most terrestrial plants form symbiosis with arbuscular mycorrhizal (AM) fungi and thus have two P uptake pathways, i.e., the direct pathway (DP) via roots, particularly root hairs, and the mycorrhizal pathway (MP) via AM fungal hyphae. AM fungi form an extraradical hyphal network to expand their contact area with soil and release carbon-rich compounds, which provide a high-energy habitat for soil bacteria. The bacteria affected by AM fungi support P nutrition of AM fungi by secreting extracellular phosphatases. During the P acquisition process, both DP and MP function and require C fixed by plant photosynthesis to maintain P transport. Plants make trade-offs between DP and MP based on C inputs and P benefits. This review first systematically explores the potential trade-offs between plant C inputs and P gains of DP and MP as well as the factors that influence such trade-offs. Then the response of AM fungi to soil nutrient heterogeneity and the mechanisms by which AM fungi select bacteria to mineralize organic P and increase the P contribution of MP were analyzed. Future studies need to apply emerging methods and technologies to accurately quantify the contribution of DP and MP to plant P absorption under different conditions and provide the theoretical basis for optimizing sustainable agricultural production systems.
Localized fertilization strategies (banding fertilizers) developed to minimize nutrient fixation by soil are used widely in intensive agricultural production. Localized fertilization encourages root foraging for heterogeneously distributed soil nutrients. This review focuses on the advances in root growth and nutrient acquisition of heterogeneously distributed soil resources. It is proposed that the incremental amplification of root foraging for nutrients induced by localized fertilization: (1) increased absorption area due to altered root morphology, (2) enhanced mobilization capacity underpinned by enhanced root physiological processes, and (3) intensified belowground interactions due to selective stimulation of soil microorganisms. The increase in root proliferation and the nutrient mobilization capacity as well as microbiome changes caused by localized fertilization can be amplified stepwise to synergistically enhance root foraging capacity, nutrient use efficiency and improve crop productivity. Engineering the roots/rhizosphere through localized, tailored nutrient application to stimulate nature-based root foraging for heterogeneously distributed soil nutrients, and scaling up of the root foraging capacity and nutrient acquisition efficiency from the rhizosphere to the field offers a potential pathway for green and sustainable intensification of agriculture.
2′-Deoxymugineic (DMA), a phytosiderophore secreted by Poaceae species, can improve iron nutrition in plants. However, little is known about how DMA influences beneficial bacteria in rhizosphere microecosystem. To address this gap, the DMA analog proline-2′-deoxymugineic (PDMA) was used to evaluate its positive effect on peanut rhizobacterial communities and network structure. This study demonstrated that PDMA can promote the absorption of several mineral nutrients in plants and activate micronutrients in the rhizosphere. Specifically, PDMA led to significant impact on the bacterial community structure in the peanut rhizosphere, resulting in a substantial increase in the relative abundance of Actinobacteriota with six beneficial rhizobacterial genera in this phylum. The Cellulosimicrobium and Marmoricola of Actinobacteriota recruited by PDMA may enhance micronutrient availability both to peanut plants and in soil. PDMA application led to the development of a tight, stable microbial network, as indicated by higher topological parameters and a greater variety of keystone genera. Functional prediction revealed that PDMA fosters microbial communication in the rhizosphere. Overall, PDMA was shown to recruit beneficial bacteria and to modulate bacterial network structure in the peanut rhizosphere. It is concluded that these findings demonstrate that phytosiderophore might promote plant growth and nutrition absorption by regulating plant–soil microecosystem.
The achievement of global food security faces exceptional challenges due to the rapid population growth, land degradation and climate change. Current farming practices, including mineral fertilizers and synthetic pesticides, alone are becoming insufficient to ensure long-term food security and ecosystem sustainability. The lack of robustness and reliability of conventional approaches warrants efforts to develop novel alternative strategies. Bio-based management strategies offer promising alternatives for improving soil health and food productivity. For example, microbial inoculants can enhance nutrient availability, crop production and stress resistance while also remediating contaminated soils. Nanobiotechnology is a promising strategy that has great potential for mitigating biotic and abiotic stresses on plant toward sustainable agriculture. Biochar (including modified biochar) serves as an effective microbial carrier, improving nutrient availability and plant growth. Also, biochar amendments have been demonstrated to have great potential facilitating soil organic carbon sequestration and mitigating greenhouse gas emissions and therefore contribute to climate change mitigation efforts. This review examines the integration of microbial inoculants, nano-fertilizers and biochar, which demonstrates as a promising strategy to enhance soil health, crop productivity and environmental sustainability. However, overcoming challenges related to their mass production, application and potential risks remains crucial. Future research should focus on optimizing these bio-amendment strategies, evaluating their economic viability and developing robust regulatory frameworks to ensure safe and effective agricultural implementation.
Bean (Phaseolus vulgaris) yields in Africa can be increased through the application of phosphorus and nitrogen fertilizers, as both nutrients are low in African soils. However, using greener technologies is preferred to mineral fertilizers for maintaining soil health. In this study, Rhizobium inoculation and moderate P supply (0, 10, 20, and 30 kg·ha−1) to two bean cultivars were evaluated in consecutive years at Hawassa for their effects on plant growth, nodulation, and grain yield. The results showed that, relative to the uninoculated control, the two bean cultivars responded strongly to Rhizobium inoculation, with strain HB-429 outperforming strain GT-9 in both 2012 and 2013. Shoot biomass, nodule number and nodule dry matter per plant were increased by 9%, 40%, and 54%, respectively, in 2012, and by 20%, 39%, and 13% in 2013 with strain HB-429 inoculation. This resulted in increased pod number per plant, seed number per pod and grain yield by 56%, 51%, and 49% in 2012, and by 38%, 25%, and 69% in 2013, respectively, with strain HB-429 inoculation. Bean inoculation with GT-9 also increased grain yield by 35% and 68% in 2012 and 2013, respectively. Applying 10–30 kg·ha−1 P to bean cultivars increased shoot biomass, nodule number, and nodule dry matter per plant by 7% to 39%, 23% to 59%, and 59% to 144% in 2012, respectively, and by 10% to 40%, 21% to 43%, and 12% to 35% in 2013, respectively. Relative to the zero-P control, adding only 10 kg·ha−1 P increased pod number per plant, seed number per pod, and grain yield by 10%, 30%, and 61% in 2012, and by 11%, 11%, and 38% in 2013, respectively. The combined use of Rhizobium inoculation with low P application (20 kg·ha−1) was found to increase bean production in Ethiopia and is thus recommended to resource-poor farmers.
The study emphasizes the significance of biochar-based nanocomposites (BNCs) in tackling waste management challenges and developing valuable materials for environmental remediation and energy generation. BNCs have enhanced adsorption and catalytic properties by incorporating nanoparticles into a charcoal matrix, offering a dual benefit for waste treatment and environmental preservation. Using waste biomass for BNC production repurposes resources and reduces the ecological impact of waste disposal. This study also addresses the existing research gaps and uncertainties hindering the widespread use of biochar and BNCs. After almost a decade of extensive research, it is crucial to address and fill the gaps in knowledge, such as long-term impacts, carbon sequestration rates, potential deforestation and economic viability. Thoroughly analyzing the entire system and establishing adaptable governance is need to realize the full benefits of BNCs. This article discusses the urgent need for sustainable technology and solutions to solve global concerns, including waste management, water quality, soil health, climate change and renewable energy. Its aim is to improve existing research by providing a comprehensive overview of the potential of biochar and BNCs in achieving sustainability objectives. It also identifies research gaps and challenges that must be addressed, directing future research directions. It extensively reviews biochar-based nanocomposites derived from waste biomass as a sustainable solution for wastewater treatment and renewable bioenergy. The constraints and future research directions have been highlighted, offering essential perspectives on the potential of biochar and BNCs in addressing global sustainability issues.
Biochar, a carbon-rich material produced by biomass pyrolysis, is valued for soil amendment, carbon sequestration and environmental remediation. Optimum biochar production depends on understanding key factors, including feedstock characteristics, pyrolysis conditions and modification methods. This review examines various pyrolysis techniques, ranging from well-established to new methods, assessing their mechanisms, strengths and limitations for large-scale production. It emphasizes the importance of feedstock selection, pyrolysis conditions and modification methods in affecting biochar yield and properties. By synthesizing current research findings, this review aims to provide insights into optimizing biochar production for sustainable utilization of lignocellulosic biomass resources.
