Integrating cutting-edge technology, nature based solutions, and circular bioeconomy for upland restoration toward regenerative landscapes

Inoculation with arbuscular mycorrhizae does not improve 137Cs uptake in crops grown in the Chernobyl region

Arbuscular mycorrhizal (AM) fungi are considered to be enormously important in contemporary agriculture and horticulture for their ability to improve crop disease and fertility management in commercial field and greenhouse crop production. Recently, commercial greenhouse producers have begun using AM inoculum to increase yields and provide sustainable growing conditions in organic and hydroponic production systems. However, strong evidence in support of their effectiveness in hydroponic production is still lacking. Future research is expected to address benefits of the use of AM fungi in hydroponic greenhouse crops, such as defense against pathogen, herbivore attack and the effective management of photo-assimilates by plants, which are essential for fruit production. In order to increase our understanding of the usefulness of AM fungi in hydroponic greenhouses, large-scale trial and a cost-benefit evaluation of the process are needed. This article discusses the use of AM fungi for improving organic and hydroponic greenhouse crop production and disease control, considering that AM fungi inoculations in soil-based greenhouses and fields have proven to be very effective.

Chapter 8 - Management of Biological and Functional Diversity in Arbuscular Mycorrhizal Fungi Within Cropping Systems

AM真菌在植物病虫害生物防治中的作用机制

Soil salinity is one of the main abiotic stresses, which restrict the plant growth and development, and therefore causes major threat to crop productivity. To minimize the crop loss, plant biologists are searching alternatives to develop salt-tolerant crop plants through different means such as plant breeding and genetic engineering. These approaches are successful and presently under use in developed countries but are too costly for the developing countries. In the present scenarios, various methods are utilized all over the globe to mitigate the adverse effect of salinity. One of the commonly used methods is to use beneficial bacteria and fungi that colonize with the plant roots and ultimately alleviate the salinity stress in plants. Among them, application of arbuscular mycorrhizal (AM) fungi has been found to be very effective in mitigating the salinity stress and also improves the crop yield. Various parameters were thoroughly studied and reported in the literature and have demonstrated positive effect in plants subjected to AM fungi under different environmental stress including saline stress. This is attributed to increased antioxidative activities, osmolytes and osmoprotectants in tolerant plants. Deficiency of mineral content in plants under salt stress is compensated by the use of AM fungi as the hyphae of AM fungi acquire minerals in abundance and thereby prevent the plants against deleterious effects of salinity stress. Efficient use of AM fungi can bring the wonders in the field of agriculture with improved yield of crop under salt stress and soil health. Besides this, identification of novel genes that regulate and maintain the biosynthesis of proline and water status in plant cells will help plant researchers to utilize this beneficial interaction in more sustainable ways. The chapter will throw light on the use of AM fungal association in alleviating salt stress in plants and how to exploit this for improved productivity under growth-limited conditions.

ABSTRACTPresent investigation studied plant water relations and soil physical properties through AM fungi (Glomus mosseae) to mitigate drought stress in Himalayan acid Alfisol having low water retentivity. Experimentation was carried out at Palampur, India during 2009–2011 in okra–pea cropping system in randomized block design (RBD) replicated thrice with 14 treatments comprising arbuscular mycorrhizal (AM) fungi, varying phosphorus nutrition and irrigation regimes at 40 and 80% available water holding capacity. Integrated use of AM fungi at varying phosphorus (P) levels and irrigation regimes led to significantly higher relative leaf water content (3% each) in okra and pea besides significantly higher xylem water potential (27%) in pea over non-AM fungi counterparts. AM fungi enhanced water-use-efficiency in okra (5–17%) and pea (12–35%) over non–AM fungi counterparts. AM fungi also improved water holding capacity (5–6%) and mean weight diameter of soil particles (4–9%) over non–AM fungi counterparts; but, had nominal or no effect on bulk density. Mycorrhizal plants maintained higher tissue water content imparting greater drought resistance to plants over non–mycorrhizal plants at moisture stress. It is inferred that integrated application of AM fungi and P at varying irrigation regimes improved the plant water relations vis-à-vis drought resistance, crop productivity, WUE, soil aggregation and water holding capacity in okra–pea sequence in Himalayan acid Alfisol.

Arbuscular mycorrhizal (AM) fungi are one of the important microbiota involved in a relationship with plant roots in which the plants and fungi both share and exchange nutrients and shelter. Cereal crops are the most essential sources of carbohydrates, dietary protein, and vitamin B for humans, and they supply the most fundamental diets. AM fungi are introduced as the optimal approach for real agricultural systems for increasing growth and productivity. According to a study from the previous decade, AM fungi were shown to promote crop growth and production, particularly in cereal crops. The AM fungi symbiosis provides a pleasant environment for microorganisms in the root and soil system, which promotes plant nutrition and water availability. AM fungi increase nutrient uptake and assimilation and also increase photosynthetic activity, which is directly associated with plant growth. Furthermore, AM fungi increase the primary and secondary metabolites, as well as soluble proteins and carbohydrates, in cereals crops. AM fungi have been shown to improve plant biomass, yield, and productivity in cereal crops. Additionally, the use of AM fungi enhances plants’ stress tolerance against various environmental stresses. In this review, we integrate the recent findings regarding the effects of AM fungi application on soil, root systems, nutrient availability and uptake, photosynthesis, metabolites, plant growth, and productivity. Furthermore, a large number of studies have been reviewed, and several limitations and research gaps have been identified that must be addressed in future studies.

Selenium (Se) is an essential trace element for humans. Arbuscular mycorrhizal fungi (AMF) play a crucial role in increasing plant micronutrient acquisition. Soybean (Glycine max (Linn.) Merr.) is a staple food for most people around the world and a source of Se. Therefore, it is necessary to study the mechanism of Se intake in soybean under the influence of AMF. In this study, the effects of fertilization with selenite and inoculation with different AMF strains (Claroideoglomus etunicatum (Ce), Funneliformis mosseae (Fm)) on the accumulation and speciation of Se in common soybean plants were discussed. We carried out a pot experiment at the soil for 90 days to investigate the impact of fertilization with selenite and inoculation with Ce and Fm on the Se fractions in soil, soybean biomass, accumulation and speciation of Se in common soybean plants. The daily dietary intake of the Se (DDI) formula was used to estimate the risk threshold of human intake of Se from soybean seeds. The results showed that combined use of both AMF and Se fertilizer could boost total Se and organic Se amounts in soyabean seeds than that of single Se application and that it could increase the proportion of available Se in soil. Soybean inoculated with Fm and grown in soil fertilized with selenite had the highest organic Se. The results suggest that AMF inoculation could promote root growth, more soil water-soluble Se and higher Se uptake. The maximum Se intake of soybean for adults was 93.15 μg/d when treated with Se fertilizer and Fm, which satisfies the needs of Se intake recommended by the WHO. Combined use of AMF inoculation and Se fertilizer increases the bioavailable Se in soil and promotes the total Se concentration and organic Se accumulation in soybean. In conclusion, AMF inoculation combined with Se fertilization can be a promising strategy for Se biofortification in soybean.

Vegetative propagation is an important method for increasing the productivity of economically important agricultural and horticultural plants. Apart from the application of phytohormones, beneficial microorganisms such as arbuscular mycorrhizal (AM) fungi being natural biofertilizers are also widely used in the field of horticultural production systems. The mutualistic association between the AM fungi and plant are not only known for their efficient water and nutrient uptake, less vulnerability to pathogens, and ability to withstand or tolerate abiotic and biotic stresses but are also involved in the production of plant hormones and adventitious root formation in asexual propagation. The inoculation of AM fungi to the rooting substrate could result in similar responses on the cuttings to those obtained through the application of exogenous plant growth regulators. In addition, the combined use of AM fungi along with plant hormones leads to increased root initiation and development of plant parts. The early inoculation of AM fungi onto the rooting medium enhances the plant growth rate of vegetatively propagated plant species after forming a symbiotic relationship with the plant. Moreover, a series of sequential signaling events are known to occur between AM fungi and the host plant during the development of roots. The present chapter focuses on the role of AM fungi in various types of vegetative propagation including cutting, layering, and grafting, the interaction between the plant hormones, and the AM symbiosis. The mechanism involved in the production of plant hormones through AM fungi and thereby the physiological changes occurring in the plant metabolism during propagation is also discussed.

ABSTRACTIn the present study, the effects of inoculation of biofertilizers (phosphorus-solubilizing arbuscular mycorrhizal (AM) fungi (AMF), Glomus intraradices, and potassium-mobilizing bacterium (KMB), Frateuria aurantia) in combination with chemical fertilizers nitrogen, phosphorus, and potassium (NPK) on growth, yield, nutrient acquisition, and quality of tobacco were observed in pot culture. Factorial combinations of biofertilizers (AMF and KMB) and chemical fertilizer (NPK) alone and in combination were applied to see the effects on growth, biomass, nutrient acquisition, and leaf quality in tobacco. Results showed that bioinocula applied either singly or in combination did not significantly enhance soil availability of P and K, indicating their unsuitability for direct application. Application of chemical fertilizer in combination with both AMF and KMB strains consistently increased availability of P and K in the soil, improved leaf quality parameters, and enhanced plant growth and vigor, suggesting the potential use of AMF and KMB as biofertilizers in sustainable tobacco crop production.

Both mutualistic and pathogenic soil microbes are known to play important roles in shaping the fitness of plants, likely affecting plants at different life cycle stages.In order to investigate the differential effects of native soil mutualists and pathogens on plant fitness, we compared survival and reproduction of two annual tallgrass prairie plant species (Chamaecrista fasciculata and Coreopsis tinctoria) in a field study using 3 soil inocula treatments containing different compositions of microbes. The soil inocula types included fresh native whole soil taken from a remnant prairie containing both native mutualists and pathogens, soil enhanced with arbuscular mycorrhizal (AM) fungi derived from remnant prairies, and uninoculated controls.For both species, plants inoculated with native prairie AM fungi performed much better than those in uninoculated soil for all parts of the life cycle. Plants in the native whole prairie soil were either generally similar to plants in the uninoculated soil or had slightly higher survival or reproduction.Overall, these results suggest that native prairie AM fungi can have important positive effects on the fitness of early successional plants. As inclusion of prairie AM fungi and pathogens decreased plant fitness relative to prairie AM fungi alone, we expect that native pathogens also can have large effects on fitness of these annuals. Our findings support the use of AM fungi to enhance plant establishment in prairie restorations.

Plants absorb mineral nutrients for growth and development from the soil though their roots; nutrient acquisition is therefore limited by their root area. To improve it, especially in nutrient-poor conditions, many plant species depend on symbiotic interactions with arbuscular mycorrhizal (AM) fungi, which provide essential nutrients obtained through the network of hyphae to the host plants. When nitrogen, phosphate, or sulfur is deficient, plants produce strigolactones, key signaling molecules, to initiate the interaction with AM fungi. Here, first, we introduce the diversity of AM fungi and their host plants. Second, we summarize the structural features of the symbiotic interaction. Third, we describe strigolactone biosynthesis and the symbiosis signaling pathway. Finally, we describe nutrient exchange system between AM fungi and host plants. Overall, we focus on the roles of AM symbiosis for nutrient acquisition in plants and detail the mechanisms. Understanding how plants adapt to their environment in response to deficiency of mineral nutrients could help to improve sustainable agricultural processes, because the use of AM fungi enables crop production in nutrient-poor environments and allows use of pesticides and fertilizers to be reduced.

Arbuscular mycorrhizal (AM) fungi are soil-borne microorganisms forming mutualistic associations with the vast majority of land plants, including most agricultural relevant crops. In this association the plant provides the fungus with plant photosynthates allowing it to complete its life cycle, while the fungus provides the plant with mineral nutrients, mainly phosphorus and can also help the plant to tolerate biotic and abiotic stresses. In regard to these benefits there is growing interest on the use of AM fungi to improve productivity and sustainability in agricultural systems. AM fungi and their interactions with plants have been extensively studied using proteomic techniques, but some difficulties have been faced. 1) Little is known about the AM fungal typical protein repertoire because it is currently impossible to grow AM fungi in pure axenic cultures; 2) Plant tissues often contain high amounts of interfering substances that make protein extraction for the study of AM interactions a difficult procedure; 3) Most nutrient exchanges between AM fungi and their host plants involve participation of membrane proteins, still poorly resolved in most separation techniques. Finally, 4) the formation of the arbuscule is an asynchronous process, making it difficult to distinguish which proteins are essential in the early or late stages of AM associations. In this review we present a historical summary of how these difficulties have been overcome by technological advances in proteomics and we discuss current and future trends in the study of the proteins involved in AM interactions.

Arbuscular mycorrhizal (AM) fungi grouped in the order Glomales (Morton and Benny 1990) interact with the roots of most land plants in nearly all ecosystems (Newman and Reddel 1987). During their development, they display particular structures like the arbuscules that are involved in different functions of the symbiosis (Smith and Gianinazzi-Pearson 1988; Read, this Vol.). Their life cycle is vegetative, and sexual stages have not been defined. The hyphae of AM fungi, like those of other Zygomycetes, are aseptated and so they are multinucleated organisms (Bonfante et al. 1987; Cooke et al. 1987). Predominantly in their spores, nuclei accumulate to rather high numbers (Viera and Glenn 1990). For these nuclei, a DNA content of 0.2 to 1 pg/ nucleus was calculated (Bianciotto and Bonfante 1992). Assuming haploidy, this indicates a genome size of 108 to 109 nucleotides, 50 to 100 times more than in other fungi. Their important role as symbionts in nearly all ecosystems (Read et al. 1992) and their peculiar development implicate the use of AM fungi in basic research (Franken et al. 1996) and sustainable agriculture (Gianinazzi et al. 1995). Their analysis and application is, however, hampered by their obligate biotrophic nature, but recently, modern techniques are allowing molecular approaches to be followed for the investigation of AM fungi.

Above-and below-ground feedback loop of maize is jointly enhanced by plant growth-promoting rhizobacteria and arbuscular mycorrhizal fungi in drier soil