Response Of Arbuscular Mycorrhizal Fungi Research Articles

Defoliation modifies the response of arbuscular mycorrhizal fungi to drought in temperate grassland

Arbuscular mycorrhizal (AM) fungi predominate in grasslands, where they play a key role in enhancing plant water uptake and plant tolerance to drought. However, how plant defoliation, which is common to grazed and cut grasslands, modifies plant and AM fungi responses to drought remains unknown. Here, we examined how defoliation intensity modified plant and AM fungi responses to drought.This was done using an in situ factorial field experiment at Colt Park meadows, northern England, whereby mixed grassland communities were subjected to different intensities of defoliation in combination with simulated summer drought. We measured a range of plant, AM fungal, and soil microbial and chemical responses to defoliation and drought, both individually and in combination, and extracted neutral lipid fatty acid (NLFA) as an indicator of AM fungi energy storage status.High intensity defoliation significantly reduced root colonization by AM fungi, and the negative impact of drought on AM fungi extraradical hyphal length was amplified under high intensity defoliation. Drought had no effect on total shoot biomass but reduced specific root length and increased soil NLFA concentrations, indicating an increase in AM fungi energy reserves. However, defoliation dampened this response, implying that defoliation suppresses AM fungi energy reserves under drought.Our findings suggest that plant communities can maintain above-ground productivity under drought with the assistance of AM fungi symbiosis, but that defoliation suppresses positive plant-fungi interactions under drought. Taken together, our findings provide new insights into how drought and defoliation, a key feature of grassland management, combine to negatively impact the plant-AM fungi associations in grassland.

Evaluating the impact of land-use change on Arbuscular Mycorrhizal Fungi (AMF) diversity and function

The ever-increasing change in land utilization has been acknowledged as a primary factor influencing ecological modifications. These alterations have reignited the interest in understanding the enduring consequences on different soil microorganisms, specifically arbuscular mycorrhizal fungi (AMF). This study investigates the effects of land-use changes (LUCs) on AMF diversity, highlighting the impact of forest degradation, intensified farming approaches, and urban growth on the structure of the AMF community and its mediated services. Research has found that deforestation leads to a decrease in AMF diversity, thereby intensifying the susceptibility of particular species to habitat degradation. The transformation of natural habitats into cultivated landscapes due to agricultural spiraling driven by the need for food production also impacts the diversity of AMF. Urbanization, an expeditiously advancing modification of land usage, has been found to have the potential to cause the fragmentation and degradation of habitats, thus impacting ecosystem benefits of AMF, such as nutrient cycling and water filtration. These changes can have far-reaching consequences for plant communities, nutrient cycling, and ecosystem functioning. Future research should prioritize the development of management strategies, investigating AMF-mediated ecosystem services, and comprehending fundamental mechanisms governing AMF responses to land-use change. This knowledge can guide sustainable land management practices emphasizing AMF diversity and function conservation.

Responses of arbuscular mycorrhizal fungi to straw return and nitrogen fertilizer reduction in a rainfed maize field

Responses of arbuscular mycorrhizal fungi to straw return and nitrogen fertilizer reduction in a rainfed maize field

Arbuscular Mycorrhizal Fungi Improve the Growth, Water Status, and Nutrient Uptake of Cinnamomum migao and the Soil Nutrient Stoichiometry under Drought Stress and Recovery.

Drought greatly influences the growth and ecological stoichiometry of plants in arid and semi-arid regions such as karst areas, where Cinnamomum migao (C. migao) is an endemic tree species that is used as a bioenergy resource. Arbuscular mycorrhizal fungi (AMF) play a key role in nutrient uptake in the soil-plant continuum, increasing plant tolerance to drought. However, few studies have examined the contribution of AMF in improving the growth of C. migao seedlings and the soil nutrient stoichiometry under drought-stress conditions. A pot experiment was conducted under natural light in a plastic greenhouse to investigate the effects of individual inoculation and Co-inoculation of AMF [Funneliformis mosseae (F. mosseae) and Claroideoglomus etunicatum (C. etunicatum)] on the growth, water status, and nutrient uptake of C. migao as well as the soil nutrient stoichiometry under well-watered (WW) and drought-stress (DS) conditions. The results showed that compared with non-AMF control (CK), AM symbiosis significantly stimulated plant growth and had higher dry mass. Mycorrhizal plants had better water status than corresponding CK plants. AMF colonization notably increased the total nitrogen and phosphorus content of C. migao seedlings compared with CK. Mycorrhizal plants had higher leaf and stem total carbon concentrations than CK. The results indicated that AM symbiosis protects C. migao seedlings against drought stress by improving growth, water status, and nutrient uptake. In general, the C. migao seedlings that formed with C. etunicatum showed the most beneficial effect on plant growth, water status, and nutrient uptake among all treatments. In the future, we should study more about the biological characteristics of each AMF in the field study to understand more ecological responses of AMF under drought stress, which can better provide meaningful guidance for afforestation projects in karst regions.

Cover Crops Modulate the Response of Arbuscular Mycorrhizal Fungi to Water Supply: A Field Study in Corn.

Cover crops (CCs) were found to improve soil health by increasing plant diversity and ground cover. They may also improve water supply for cash crops by reducing evaporation and increasing soil water storage capacity. However, their influence on plant-associated microbial communities, including symbiotic arbuscular mycorrhizal fungi (AMF), is less well understood. In a corn field trial, we studied the response of AMF to a four-species winter CC, relative to a no-CC control, as well as to two contrasting water supply levels (i.e., drought and irrigated). We measured AMF colonization of corn roots and used Illumina MiSeq sequencing to study the composition and diversity of soil AMF communities at two depths (i.e., 0-10 and 10-20 cm). In this trial, AMF colonization was high (61-97%), and soil AMF communities were represented by 249 amplicon sequence variants (ASVs) belonging to 5 genera and 33 virtual taxa. Glomus, followed by Claroideoglomus and Diversispora (class Glomeromycetes), were the dominant genera. Our results showed interacting effects between CC treatments and water supply levels for most of the measured variables. The percentage of AMF colonization, arbuscules, and vesicles tended to be lower in irrigated than drought sites, with significant differences detected only under no-CC. Similarly, soil AMF phylogenetic composition was affected by water supply only in the no-CC treatment. Changes in the abundance of individual virtual taxa also showed strong interacting effects between CCs, irrigation, and sometimes soil depth, although CC effects were clearer than irrigation effects. An exception to these interactions was soil AMF evenness, which was higher in CC than no-CC, and higher under drought than irrigation. Soil AMF richness was not affected by the applied treatments. Our results suggest that CCs can affect the structure of soil AMF communities and modulate their response to water availability levels, although soil heterogeneity could influence the final outcome.

Effects of Arbuscular Mycorrhizal Fungi on Leaf N: P: K Stoichiometry in Agroecosystem

Leaf nitrogen (N), phosphorus (P), and potassium (K) stoichiometry can reflect plant strategies of nutrient allocation, which play key roles in ensuring food security and maintaining nutrient balance in the agroecosystem. Arbuscular mycorrhizal fungi (AMF) inoculation is an effective and green management measure affecting nutrient uptake and utilization strategies, especially in the agroecosystem. However, the interplay between AMF and leaf nutrient stoichiometry that is important for sustainable agriculture remain underexplored. Therefore, the efficacy of AMF in improving leaf nutrients of host plants in agricultural ecosystems were tested with meta-analysis by 1932 pairs of observations in research publications from 1995 to 2022. Overall analysis showed that AMF inoculation increases leaf N, P, and K by 8.75%, 24.61%, and 13.54%, respectively. Moreover, leaf P: K increased by 11.74% by AMF inocula, but leaf N: P and N: K of host plants decreased by 15.38% and 5.52%, respectively. Furthermore, the AMF effect on leaf nutrient stoichiometry was significantly regulated by species, life cycle, and growth habits of host plants. The prominent efficacy of AMF was higher for leaf P in fruit (30.06%), perennial (30.19%), and woody plants (31.6%) than other groups. Moreover, AMF effects on leaf N: P: K stoichiometry of inoculated crops varied depending on the identity of AMF. The Glomeraceae (especially Rhizophagus genera) increased more leaf P content than other AMF families. Thus, the leaf nutrient of host plants significantly increased by AMF inocula, especially leaf P content in the agroecosystem. The effect of AMF on leaf N: P: K stoichiometry was related to plant species, plant life cycle, plant growth habits, and the identity of AMF. These findings highlight the response of AMF to the strategies of nutrient in host plants and provide a theoretical and applicable way for better crop yield and sustainable agriculture.

Environmental response of arbuscular mycorrhizal fungi under soybean cultivation at a regional scale.

Climate change, the shortage of fertilizers and reduced land for cultivation have drawn attention to the potential aid provided by soil-borne organisms. Arbuscular mycorrhizal fungi (AMF) offer a wide range of ecosystem benefits and hence, understanding the mechanisms that control AMF occurrence and maintenance is essential for resilient crop production. We conducted a survey of 123 soybean fields located across a 75,000-km2 area of Argentina to explore AMF community composition and to quantify the impact of soil, climate, and geographical distance on these key soil organisms. First, based upon morphological identification of spores, we compiled a list of the AMF species found in the studied area and identified Acaulospora scrobiculata and Glomus fuegianum as the most frequent species. G. fuegianum abundance was negatively correlated with precipitation seasonality and positively correlated with mean annual precipitation as well as mycorrhizal colonisation of soybean roots. Second, we observed that species richness was negatively correlated with soil P availability (Bray I), clay content and mean annual precipitation. Finally, based on partitioning variation analysis, we found that AMF exhibited spatial patterning at a broad scale. Therefore, we infer that geographical distance was positively associated with spore community composition heterogeneity across the region. Nevertheless, we highlight the importance of precipitation sensitivity of frequent species, overall AMF richness and community composition, revealing a crucial challenge to forthcoming agriculture considering an expected change in global climate patterns.

Arbuscular Mycorrhizal Fungus “Rhizophagus irregularis” impacts on physiological and biochemical responses of ryegrass and chickpea plants under beryllium stress

Heavy metals such as beryllium (Be) have been identified as toxic for plants with a negative impact on plant growth. Therefore, there is an urgent need for environmentally friendly techniques to reduce Be toxicity on plant growth and productivity. To this end, arbuscular mycorrhizal fungi (AMF) are widely applied to induce plant growth and stress tolerance. However, how AMF-plant symbiosis can support plants under Be stress has not been studied. Accordingly, we investigated the physiological and biochemical responses of AMF inoculated ryegrass and chickpea plants to Be stress. The associated changes in Be uptake and accumulation, photosynthesis, oxidative stress, carbon and nitrogen metabolism were studied. Soil contamination with Be induced higher Be accumulation, particularly in ryegrass, which consequentially reduced plant growth and photosynthesis. However, photorespiration and oxidative damage (H2O2 accumulation, lipid oxidation, and LOX activity) were increased, mainly in ryegrass. In both plant species, AMF inoculation reduced Be accumulation and mitigated growth inhibition and oxidative damage, but to a more extent in ryegrass. This could be explained by improved photosynthesis as well as the upregulation of osmoprotectants i.e., sucrose and proline biosynthesis pathways. The increase in proline level was consistent with higher nitrogen (N) metabolism as reflected by N level and nitrate reductase. Species-specific responses were recorded and supported by principal component analysis. This study provided insight into the mechanism of AMF's impact on Be-stressed ryegrass and chickpea plants. Hence, the current research suggested that AMF inoculation could be used as a viable strategy to mitigate Be phytotoxicity in ryegrass and chickpea plants.

Field inoculation responses of arbuscular mycorrhizal fungi versus endophytic fungi on sugar metabolism associated changes in fruit quality of Lane late navel orange

Arbuscular mycorrhizal (AM) fungi and plants require sugars, especially during fruit ripening stage, while the underlying mechanism influencing sugar accumulation in response to AM fungi is still unclear. The objective of this study was to analyze the field inoculation response of three AM fungi (Acaulospora scrobiculata, Diversispora spurca, and D. versiformis) and an endophytic fungus (Piriformospora indica) on internal as well as external quality parameters of Lane late navel orange (Citrus sinensis) fruits, with emphasis on monosaccharide and disaccharide components and expressions of sucrose-associated enzyme genes and sugar transporter genes. Root fungal colonization rate increased by 51.2−109.6% with the inoculation of D. spurca displaying the best response after two years of field inoculation. The fungal introduction also improved the external fruit quality attributes to some extent, especially longitudinal and transverse diameter, sarcocarp weight, and fruit coloration value in response to inoculation of A. scrobiculata and P. indica. Fruit number increased in response to inoculation with D. versiformis. Although none of the four symbiotic fungi influenced the soluble solids of fruits, however fruit titratable acids registered a significant reduction leading to an increase in soluble solids-titratable acids ratio in response to A. scroblculata and D. spurca. Inoculation with A. scrobiculata and D. spurca also reduced sucrose while increased glucose, fructose, and trehalose concentrations in fruit sarcocarps, along with up-regulated expressions of CsVINV1, CsA/NINV4, and CsSWEET in fruit sarcocarps, suggesting that AM fungi played a pivotal role in sucrose transport, synthesis, and cleavage in fruits. In contrast, inoculation with P. indica only increased the sucrose and up-regulated expressions of CsSPS1 and CsSPS4 in fruit sarcocarps, implying that Pi mainly triggered the sucrose synthesis in fruits. These symbiotic fungi increased concentration of one of the three sweeteners (arabinose, xylitol and fucose) in fruit sarcocarps, with an exception of A. scrobiculata responding to an increase in the three sweeteners. These results provided strong clues that symbiotic fungi have an important role in improving the fruit size and different sugar components in citrus fruits by regulating the expression of genes related to sucrose synthesis, cleavage, and transport, with A. scrobiculata outplaying the response of other three symbiotic fungi.

Mowing Did Not Alleviate the Negative Effect of Nitrogen Addition on the Arbuscular Mycorrhizal Fungal Community in a Temperate Meadow Grassland.

As nitrogen deposition intensifies under global climate change, understanding the responses of arbuscular mycorrhizal (AM) fungi to nitrogen deposition and the associated mechanisms are critical for terrestrial ecosystems. In this study, the effects of nitrogen addition and mowing on AM fungal communities in soil and mixed roots were investigated in an Inner Mongolia grassland. The results showed that nitrogen addition reduced the α-diversity of AM fungi in soil rather than that of root. Besides, nitrogen addition altered the composition of AM fungal community in soil. Soil pH and inorganic nitrogen content were the main causes of changes in AM fungal communities affected by nitrogen addition. Mowing and the interaction of nitrogen addition and mowing had no significant effect on AM fungal community diversity. In contrast, while mowing may reduce the negative effects of nitrogen addition on the richness and diversity of plants by alleviating light limitation, it could not do so with the negative effects on AM fungal communities. Furthermore, AM fungal communities clustered phylogenetically in all treatments in both soil and roots, indicating that environmental filtering was the main driving force for AM fungal community assembly. Our results highlight the different responses of AM fungi in the soil and roots of a grassland ecosystem to nitrogen addition and mowing. The study will improve our understanding of the effects of nitrogen deposition on the function of ecosystem.

Responses of arbuscular mycorrhizal fungi to elevated atmospheric CO2 concentration and warming: A review

Global changes have profound impacts on biodiversity and ecological functioning of terrestrial ecosystems. Arbuscular mycorrhizal (AM) fungi can form symbiotic associations with most terrestrial plant species and play an important role in nutrient acquisition of host plants, promotion of plant growth, and maintenance of plant diversity. In this review, we primarily focused on the responses and feedbacks of AM fungal community and functioning to elevated atmospheric CO2(eCO2) and warming in forest and grassland ecosystems. eCO2 influenced AM fungi mainly through indirectly impacting host plants and soil carbon inputs. A majority of previous studies reported that eCO2 could enhance the abundance and activity of AM fungi, and influence their diversity and community composition. Warming could have direct and indirect (via plant and/or soil pathways) impacts on AM fungi. Warming significantly altered the community compositions of AM fungi in forest soils. But the results from grassland were not consistent. We identified some outstanding problems in current studies and proposed future research topics which deserve more attentions. Our aim was to elucidate the AM fungal responses and adaptation to eCO2 and warming and to improve our understanding of AM fungal functioning in soil ecological processes. This review could provide insights into the implications of AM fungi to mitigate global change and improve the resilience of soil functions, as well as climate change adaptation of ecosystems.

Impact of anthropogenically-disturbed environmental parameters on arbuscular mycorrhizal fungi

Anthropogenic activities in the last century have highly impacted our physical environment in many different ways. Burning of fossil fuels, pollution, deforestation, and production of pesticides and fertilizers have elicited climate change (global warming) and have inadvertently disturbed the ecosystem balance. Arbuscular mycorrhizal fungi (AMF) which are widely distributed in terrestrial ecosystems form a mutualistic interaction known as arbuscular mycorrhiza(AM) with the roots of most land plants. Their contribution to ecosystem functioning by regulating plant function, nutrient uptake, stress resistance, and community interactions is noteworthy. Different studies have suggested that an increase in temperature, carbon dioxide enrichment, and increased nutrient deposition in the ecosystem which is the result of imprudent human activities strongly impact the colonization, diversity, and function of AMF in the terrestrial ecosystems. This review briefly describes the responses of AMF to different climatic factors and their consequences on host plant functioning and productivity. Understanding the dynamics of plant-fungal associations in the context of global climate change will help in designing strategies to alleviate detrimental anthropogenic impacts to protect AMF diversity and consequently ecosystem functioning and its sustainability.

The effect of amendments on Lolium perenne roots arbuscular mycorrhizal fungi colonization when cultivated in contaminated soil

Arbuscular Mycorrhizal Fungi that colonize the roots of plants growing on lands contaminated by heavy metals may influence the phytostabilization process reducing the translocation of metals to the aboveground parts of the plant. This study aimed to evaluate the effects of soil amendments (lime and lignite) on the concentration of the bioavailable form of heavy metals (CaCl2 extraction) in soil and on the colonization of Arbuscular Mycorrhizal Fungi in the roots of Lolium perenne when cultivated in contaminated soil. During the experiment, the bioavailability of Pb, Cd, and Zn in soil was significantly reduced after application of the amendments, causing an increase of L. perenne shoot dry biomass. It was observed that the higher dose of lime (0.5%) resulting in amplified values of relative mycorrhizal intensity. However, independently of the dose, the treatments increased the occurrence of arbuscules in L. perenne roots, with the highest value observed after the application of 0.25% lime with 5% lignite. The results for the first time present the effect of lime and lignite application on the L. perenne roots colonization by Arbuscular Mycorrhizal Fungi indicating the increase of occurrence of arbuscules. These findings suggest that in order to explain the different responses of Arbuscular Mycorrhizal Fungi to the applied treatment further investigations are needed to identify the spore morphology. The results of the experiment were implemented to stabilize heavy metals during remediation of a spoil heap in Ruda Śląska, Poland.

Community response of arbuscular mycorrhizal fungi to extreme drought in a cold-temperate grassland.

Climate extremes pose enormous threats to natural ecosystems. Arbuscular mycorrhizal (AM) fungi are key plant symbionts that can affect plant community dynamics and ecosystem stability. However, knowledge about how AM fungal communities respond to climate extremes in natural ecosystems remains elusive. Based on a grassland extreme drought experiment in Inner Mongolia, we investigated the response of AM fungal communities to extreme drought in association with plant communities. The experiment simulated two types of extreme drought (chronic/intense) of once-in-20-year occurrence. AM fungal richness and community composition exhibited high sensitivity to extreme drought and were more sensitive to intense drought than chronic drought. This community sensitivity (i.e. decline in richness and shifts in community composition) of AM fungi can be jointly explained by soil moisture, plant richness, and aboveground productivity. Notably, the robustness of the plant-AM fungal community co-response increased with drought intensity. Our results indicate that AM fungal communities are sensitive to climate extremes, and we propose that the plant community mediates AM fungal community responses. Given the ubiquitous nature of AM associations, their climate sensitivity may have profound consequences on plant communities and ecosystem stability under climate change.

The roles and performance of arbuscular mycorrhizal fungi in intercropping systems

Intercropping, which gains productivity and ecological benefits through plant facilitative interactions, is a practice often associated with sustainable agriculture. In such systems, arbuscular mycorrhizal (AM) fungi and the hyphal networks play key roles in plant facilitation by promoting connectivity, mediating interplant transfer of metabolic resources, and managing weeds, pathogens, and contaminants. This review states that the symmetrically or unsymmetrically delivered resources via AM fungi are imperative to maintain facilitative interactions between intercrops. In addition, the responses of AM fungi to intercropping are also discussed, including changes in abundance, diversity, community composition and colonization level. Although general proliferations in AM fungi via intercropping have been shown, the plant hosts and neighbors may exert different influences on AM fungi. Therefore, further research is needed in quantifying the mediating role of AM fungi on outputs of intercropping systems, clarifying the driving forces, and exploring the causation between these processes and the changes in AM fungi themselves. To conclude, the integration with AM fungi extends the understanding of key soil biological processes driving plant facilitation and will guide efforts to optimizing intercropping systems.

Depression of the soil arbuscular mycorrhizal fungal community by the canopy gaps in a Japanese cedar (Cryptomeria japonica) plantation on Lushan Mountain, subtropical China.

Both canopy gaps (CG) and arbuscular mycorrhizal fungi (AMF) play key roles in seedling establishment and increasing species diversity in forests. The response of AMF to canopy gaps is poorly understood. To assess the long-term effects of canopy gaps on soil AMF community, we sampled soil from plots in a 50-year Cryptomeria japonica (L.f.) D. Don. plantation, located in Lushan Mountain, subtropical China. We analyzed the AMF community, identified through 454 pyrosequencing, in soil and edaphic characteristics. Both richness and diversity of AMF in CG decreased significantly compared to the closed canopy (CC). The differences of the AMF community composition between CG and CC was also significant. The sharp response of the AMF community appears to be largely driven by vegetation transformation. Soil nutrient content also influenced some taxa, e.g., the low availability of phosphorus increased the abundance of Acaulospora. These results demonstrated that the formation of canopy gaps can depress AMF richness and alter the AMF community, which supported the plant investment hypothesis and accentuated the vital role of AMF–plant symbioses in forest management.

Effects of elevated CO2 on arbuscular mycorrhizal fungi associated with Robinia pseudoacacia L. grown in cadmium-contaminated soils

As symbionts capable of reciprocal rewards, arbuscular mycorrhizal fungi (AMF) can alleviate heavy metal toxicity to host plants and are easily influenced by elevated CO2 (ECO2). Although the individual effects of ECO2 and cadmium (Cd) on AMF have been widely reported, the response of AMF to ECO2 + Cd receives little attention. We evaluated the combined effects of ECO2 and Cd on AMF in the rhizosphere soil and roots of Robinia pseudoacacia L. seedlings. Under ECO2 + Cd relative to Cd, AMF gene copies and richness in rhizosphere soils increased (p < 0.05) and the diversity reduced (p < 0.05) at 4.5 mg Cd kg−1 dry soil; whereas root AMF abundance at 4.5 mg Cd kg−1 dry soil and the diversity and richness reduced (p < 0.05). Elevated CO2 caused obvious differences in the dominant genera abundance between rhizosphere soils and roots upon Cd exposure. Responses of C, water-soluble organic nitrogen (WSON), pH, and diethylene triamine penta-acetic acid (DTPA)-Cd in rhizosphere soils and root N to ECO2 shaped dominant genera in Cd-polluted rhizosphere soils. Levels of DTPA-Cd, WSON, C and pH in rhizosphere soils and C/N ratio, N, and Cd in roots to ECO2 affected (p < 0.05) dominant genera in roots under Cd exposure. AMF richness and diversity were lower in roots than in rhizosphere soils. Elevated CO2 altered AMF communities in rhizosphere soils and roots of R. pseudoacacia seedlings exposed to Cd. AMF associated with R. pseudoacacia may be useful/interesting to be used for improving the phytoremediation of Cd under ECO2.

Responses of Arbuscular Mycorrhizal Symbiosis to Abiotic Stress: A Lipid-Centric Perspective.

Arbuscular mycorrhizal (AM) fungi are one of the most important soil microbial resources that help host plants cope with various abiotic stresses. Although a tremendous number of studies have revealed the responses of AM fungi to abiotic stress and their beneficial effects transferred to host plants, little work has focused on the role of lipid metabolism in AM fungi under abiotic stress conditions. AM fungi contain a large amount of lipids in their biomass, including phospholipids (PLs) in their hyphal membranes and neutral lipids (NLs) in their storage structures (e.g., vesicles and spores). Recently, lipid transfer from plants to AM fungi has been suggested to be indispensable for the establishment of AM symbiosis, and extraradical hyphae are capable of directly taking up lipids from the environment. This experimental evidence highlights the importance of lipids in AM symbiosis. Moreover, abiotic stress reduces lipid transfer to AM fungi and promotes arbuscule collapse as well as the hydrolysis and conversion of PLs to NLs in collapsed arbuscules. Overall, this knowledge encourages us to rethink the responses of AM symbiosis to abiotic stress from a lipid-centric perspective. The present review provides current and comprehensive knowledge on lipid metabolism in AM fungi, especially in response to various abiotic stresses. A regulatory role of abscisic acid (ABA), which is considered a “stress hormone,” in lipid metabolism and in the resulting consequences is also proposed.

Identifying citrus CBL and CIPK gene families and their expressions in response to drought and arbuscular mycorrhizal fungi colonization

The calcineurin B-like protein (CBL)-interacting protein kinase (CIPK) complex is an essential calcium sensor and contributes to biotic and abiotic stress responses. However, citrus CBL and CIPK gene family members and their underlying roles during drought and arbuscular mycorrhizal fungi (AMF) colonization remain relatively unknown. In the present study, CBLs and CIPKs were characterized in Citrus sinensis by analyzing the presence of specific domains such as the elongation factor (EF)-hand motif in CBLs, and a protein kinase and an Asn-Ala-Phe domain in CIPKs. After mining the C. sinensis genome, we identified 8 CsCBLs and 17 CsCIPKs. Among these genes, three CsCBLs and nine CsCIPKs showed syntenic relationships with the Arabidopsis thaliana homologs AtCBLs and AtCIPKs, respectively. According to gene expression and cis-acting element analysis, all 8 CsCBLs and 16 CsCIPKs were expressed in the roots, where the regulation of expression was not consistent with their promoter cis-elements. Drought treatment remarkably downregulated the expression of CsCBL8 and upregulated CsCBL7, CsCIPK4, and CsCIPK7 expressions. The AMF colonization induced CsCBL4, 5, 6, and 7 as well as CsCIPK2, 4, 10, 11, 13, 14, and 16 expressions and repressed CsCBL1, 2, 3, and 8 and CsCIPK1, 3, 6, 8, 9, and 12 expressions. Based on the expression data and co-expression analysis, CsCBL1-CsCIPK1, CsCBL1-CsCIPK3, CsCBL1-CsCIPK6, and CsCBL1-CsCIPK9 showed the significant positive correlations to drought and AMF responses.

Ionomic and biochemical responses of maize plant (Zea mays L.) inoculated with Funneliformis mosseae to water-deficit stress

The response of arbuscular mycorrhizal fungi (AMF)-inoculated plants to environmental stresses including drought stress is a complex phenomenon that involves activation or modification of processes occurring at physiological, biochemical, and molecular levels. However, the information on the ionomic and biochemical responses of AMF-inoculated plants under drought stress is limited. This study aimed to investigate the effect of AM fungus Funneliformis mosseae on maize plant growth, uptake of nutrients, and antioxidant responses of the plant to water-deficit stress under greenhouse conditions in a sterilized calcareous soil(Typic Calcixerepts). The experiment was laid out in a two-factor experiment in a completely randomized design with four replicates. The experimental factors included three different water regimes (100%, 70%, and 50% field capacity (FC)) and AM fungus at two levels (inoculated with or without F. mosseae). Water-deficit stress reduced plant biomass, chlorophyll index, nutrients uptake (P, K, Ca, Mg, Fe, Zn, Mn and Cu in shoots and roots), root colonization but increased malondialdehyde content. Inoculation with F. mosseae had a positive effect on plant growth, chlorophyll index, and nutrients uptake. Activities of guaiacol peroxidase (12.4%), superoxide dismutase (6.5%), and catalase (21.6%) as well as total phenolic content (62.5%) were higher in mycorrhizal plants as compared to non-mycorrhizal plants at 50% FC level. Lipid peroxidation (36.6% and 39.4% at 70 and 50% FC levels, respectively) was higher in non-AM plants as compared to AM plants. Under non-stress conditions, growth and nutrients uptake of mycorrhizal plants were greater than non-mycorrhizal ones. In general, the results of this study indicated that inoculation with F. mosseae through the improvement of ionomic and biochemical status of the plant can mitigate the detrimental effects of water-deficit stress on maize plants. The results of this study also suggest that the shoot and root ionome could be a useful phenotype for understanding the complicated interaction between F. mosseae and maize plant by providing readouts indicative of the biochemical processes occurring in the roots and shoots.