Host Plant Growth Research Articles

Phytoprotection potential of Fusarium proliferatum for control of Botryosphaeria dieback pathogens in grapevine

The economic impact of grapevine trunk diseases (GTDs) is increasing worldwide, due to the lack of efficient and simple control protocols for these disease complexes. Possible and efficient GTD management strategies must consider the complexity of host physiological alterations affecting metabolism and defense responses determined by GTD pathogens, and linked to disease expression. In this complexity, the use of biocontrol agents could give advantages in GTD control methods. The effect of the potential biocontrol agent (BCA) Fusarium proliferatum was evaluated using in vitro tests and in dual inoculation with the Botryosphaeria dieback agent Neofusicoc-cum parvum in planta. Artificial inoculations were performed in greenhouse and vineyard experiments at three key vine growth stages, the onset of G (separated clusters), I (flowering) or M (veraison) stages. The biocontrol potential was assessed using pathogenicity tests and transcriptomic analyses. Results showed that the F. proliferatum has potential for phytoprotection, with disease control efficiency related to host plant growth stage. Flowering was confirmed as the growth stage when disease control was least, and efficiency of activated defense responses against pathogen infection was minimum.

Nitrogen fertilization altered arbuscular mycorrhizal fungi abundance and soil erosion of paddy fields in the Taihu Lake region of China.

Arbuscular mycorrhizal (AM) fungi were of importance in mitigating soil erosion, which was highly influenced by biotic and abiotic factors, such as host plant growth and soil nutrient. To investigate the impact of nitrogen (N) fertilization on seasonal variance in AM colonization and soil erosion, we conducted a field experiment with rice cultivation under four N fertilizer levels (0kgNha-1, 270kgNha-1, 300kgNha-1, and 375kgNha-1 plus organic fertilizers) in the Taihu Lake region, China. We investigated AM colonization before rice transplantation, during rice growth, and after rice harvest. We also assessed soil splash erosion of intact soil cores sampled at tillering and after rice harvest. We found that AM colonization (indicated by percentage of root length colonization) varied from 15 to 73%, which was attributed to rice growth, N fertilization, and their interaction. Soil loss due to splash erosion was cut down by organic N fertilizer at tillering, while higher inorganic N fertilization significantly increased soil loss after rice harvest. Additionally, we found significantly negative relationships of AM colonization to soil loss but positive relationships to soil aggregate stability. We highlighted the potential role of AM fungi in decreasing soil erosion and suggested that high N fertilization should be considered carefully when seeking after high yields.

Effects of arbuscular mycorrhizal fungi on inoculated seedling growth and rhizosphere soil aggregates

Arbuscular mycorrhizal fungi (AMF) inoculation have been shown to enhance host plant growth and rhizosphere soil aggregates largely due to the combined effect of extraradical hyphae and glomalin-related soil proteins but their effects on rocky desertified soils remain unknown. Extensive karst area of southwest China has undergone rocky desertification because of soil erosion and vegetation degradation. Karst soils in this area are mainly composed of silty clay loam developed from carbonate rock erosion under subtropical humid monsoon climate. We tested the hypothesis that AMF colonization of tree seedlings would improve water stable aggregates of degraded karst soil and enhance seedling growth. Seedlings of two tree species, Toona sinensis and Delavaya toxocarpa suitable for afforestation in karst area, were inoculated separately with three AMF, Funneliformis mosseae, Glomus versiforme and Rhizophagus intraradices in pots containing rocky desertified soil. Non-inoculated seedlings were used as control. After 12 months we found that the percentage of water stable aggregates (diameter >0.25 mm; WSA>0.25) in the rhizosphere soil of the inoculated seedlings was increased by 15.6–20.5% compared to control. AMF colonization significantly increased the quantity of aggregates with diameter > 2 mm compared to control but soil aggregates of size class 0.25 – 0.5 mm decreased significantly in inoculated seedlings, regardless of tree species. Shoot biomass of inoculated T. sinensis and D. toxocarpa seedling was increased by 15.7–21.2% and 8.5–20.4%, respectively compared to non-inoculated seedlings. In contrast, AMF inoculation minimally influenced the root biomass of the two tree species. The easily extractable glomalin (EEG) content and mean weight diameter (MWD) of rhizospheric soil of the inoculated seedlings increased by 28.9–75.1% and 31.7–48.1%, respectively compared to control. The AMF colonization was highly correlated with WSA>0.25, EEG and MWD. Overall results support our hypothesis that AMF colonization enhance the quantity of rhizospheric soil aggregates and improve the growth of host seedlings. We conclude that planting tree species inoculated with AMF has a potential for restoration of degraded karst ecosystem. In future research other locally adapted tree and shrub species should be tested following AMF inoculation to prepare a wider planting stocks to be used in restoration of degraded karsts.

PERBANYAKAN BERBAGAI JENIS MIKORIZA ARBUSKULA DI BERBAGAI JENIS TANAMAN INANG

The type of mycorrhizae has the behavior of AM colonies on plant roots and different spore formation, so the selection of important host plants in multiplication of AM. This study aimed to test the mycorrhizal propagation and AM colonies in various types of mycorrhiza ( Glomus sp. and Acaulospora sp.) in sweet maize, green beans and odot grass, and to study available soil P and growth of host plants (sweet maize, green beans and odot grass) inoculated with different types of mycorrhiza ( Glomus sp. and Acaulospora sp.). The research included 3 stages of activities, i.e. soil sampling, isolation and identification of mycorrhizae, and propagation of spores. The study used a factorial completely randomized design, consisted of two factors host species (sweet maize, green beans and odot grass) and the types of mycorrhiza (control, Glomus sp. and Acaulospora sp.), totaling 9 treatments and 4 replication of each. The results showed that there were signifance differences in the number of mycorrhizal spores and AM colonies in plant roots ( Glomus sp. and Acaulospora sp.). Further, the growth of host plant by aplication of different type of AM was significantly different (P<0,05). Application of mychorriza on plants gave significant effect on available P at 56 days after planting, except in sweet maize.

Two herbicides, two fungicides and spore-associated bacteria affect Funneliformis mosseae extraradical mycelium structural traits and viability.

The extraradical mycelium (ERM) produced by arbuscular mycorrhizal fungi is fundamental for the maintenance of biological fertility in agricultural soils, representing an important inoculum source, together with spores and mycorrhizal root fragments. Its viability and structural traits, such as density, extent and interconnectedness, which are positively correlated with the growth and nutrition of host plants, may be affected by different agronomic practices, including the use of pesticides and by different mycorrhizospheric communities. This work, carried out using a whole-plant experimental model system, showed that structural traits of ERM, such as length and density, were strongly decreased by the herbicides dicamba and glufosinolate and the fungicides benomyl and fenhexamid, while anastomosis frequency and hyphal branching were differentially modulated by singly inoculated mycorrhizospheric bacteria, depending on their identity.

Parasitism changes rhizospheric soil microbial communities of invasive Alternanthera philoxeroides, benefitting the growth of neighboring plants

Parasitic plants represent a peculiar and highly specialized group and are important members of terrestrial ecosystems. Although much is known about how parasitic plants influence growth, reproduction, physiology, and metabolism of host plants, their possible role as modulators of microbial community properties remains largely unexplored. Using next-generation sequencing of the bacterial 16S rRNA gene and fungal rRNA internal transcribed spacer, we analyzed the effects of parasitism on both composition and diversity of soil microbial communities in the rhizosphere of an invasive species Alternanthera philoxeroides parasitized by Cuscuta australis, and feedback effects of parasitism-altered soil microbes on the growth of the host (A. philoxeroides) and on the co-existing native Trifolium repens. Cuscuta australis parasitism increased alpha-diversity and changed the composition of both bacterial and fungal community in the rhizospheric soil of A. philoxeroides. Alternanthera philoxeroides produced significantly less plant biomass when grown in soils inoculated with microbial communities of A. philoxeroides parasitized by C. australis compared to non-parasitized soils and control soils, whereas T. repens produced significantly more biomass grown in soils inoculated with microbial communities of A. philoxeroides parasitized by C. australis. Inoculation with soil microbial communities of A. philoxeroides not parasitized by C. australis increased the competitiveness of A. philoxeroides to neighboring T. repens, whereas, inoculation with soil microbial communities of A. philoxeroides parasitized by C. australis reduced the competitiveness of A. philoxeroides. These results suggest that plant parasitism-induced changes in soil microbiome can negatively affect host plant growth, and positively affect the growth of the native neighbor plants, via shift of the competitive hierarchy between the host and co-existing native plants.

Transcriptome analysis of soybean (Glycine max) root genes differentially expressed in rhizobial, arbuscular mycorrhizal, and dual symbiosis.

Soybean (Glycine max) roots establish associations with nodule-inducing rhizobia and arbuscular mycorrhizal (AM) fungi. Both rhizobia and AM fungi have been shown to affect the activity of and colonization by the other, and their interactions can be detected within host plants. Here, we report the transcription profiles of genes differentially expressed in soybean roots in the presence of rhizobial, AM, or rhizobial-AM dual symbiosis, compared with those in control (uninoculated) roots. Following inoculation, soybean plants were grown in a glasshouse for 6weeks; thereafter their root transcriptomes were analyzed using an oligo DNA microarray. Among the four treatments, the root nodule number and host plant growth were highest in plants with dual symbiosis. We observed that the expression of 187, 441, and 548 host genes was up-regulated and 119, 1,439, and 1,298 host genes were down-regulated during rhizobial, AM, and dual symbiosis, respectively. The expression of 34 host genes was up-regulated in each of the three symbioses. These 34 genes encoded several membrane transporters, type 1 metallothionein, and transcription factors in the MYB and bHLH families. We identified 56 host genes that were specifically up-regulated during dual symbiosis. These genes encoded several nodulin proteins, phenylpropanoid metabolism-related proteins, and carbonic anhydrase. The nodulin genes up-regulated by the AM fungal colonization probably led to the observed increases in root nodule number and host plant growth. Some other nodulin genes were down-regulated specifically during AM symbiosis. Based on the results above, we suggest that the contribution of AM fungal colonization is crucial to biological N2-fixation and host growth in soybean with rhizobial-AM dual symbiosis.

Brassinosteroids Affect the Symbiosis Between the AM Fungus Rhizoglomus irregularis and Solanaceous Host Plants.

Together with several proteins involved in brassinosteroid (BR) signaling and synthesis, the membrane steroid binding protein 1 (MSBP1) was identified within the interactome of the sucrose transporter of tomato (SlSUT2). We asked whether MSBP1 is also involved in BR signaling as assumed for the AtMSBP1 protein from Arabidopsis and whether it impacts root colonization with arbuscular mycorrhizal (AM) fungi in a similar way as shown previously for SlSUT2. In addition, we asked whether brassinosteroids per se affect efficiency of root colonization by AM fungi. We carried out a set of experiments with transgenic tobacco plants with increased and decreased MSBP1 expression levels. We investigated the plant and the mycorrhizal phenotype of these transgenic plants and tested the involvement of MSBP1 in BR metabolism by application of epi-brassinolide and brassinazole, an inhibitor of BR biosynthesis. We show that the phenotype of the transgenic tobacco plants with increased or reduced MSBP1 expression is consistent with an inhibitory role of MSBP1 in BR signaling. MSBP1 overexpression could be mimicked by brassinazole treatment. Interestingly, manipulation of MSBP1 expression in transgenic tobacco plants not only affected plant growth and development, but also the host plant responses toward colonization with AM fungi, as well as arbuscular architecture. Moreover, we observed that brassinosteroids indeed have a direct impact on the nutrient exchange in AM symbiosis and on the biomass production of colonized host plants. Furthermore, arbuscular morphology is affected by changes in MSBP1 expression and brassinolide or brassinazole treatments. We conclude that host plant growth responses and nutrient exchange within the symbiosis with AM fungi is controlled by brassinosteroids and might be impeded by the MSBP1 protein.

Aspergillus flavus Promoted the Growth of Soybean and Sunflower Seedlings at Elevated Temperature.

The current climate changes in the form of global warming are one of the leading threats to agricultural crops (including soybean and sunflower). To enable the crops to cope with the heat stress, innovative steps are needed to be taken as soon as possible. Fungal endophytes are known to secrete secondary metabolites that promote the growth of host plants under stress conditions. Therefore, we have isolated endophytic fungus from Euphorbia indica (a wild desert plant) and tested it for plant growth promoting activities. The culture filtrate of the fungal strains exhibited the presence of secondary metabolites. Higher amounts of indole acetic acid (IAA), salicylic acid (SA), flavonoids, and phenolics have been found in the culture filtrate. The 18S rDNA sequence homology and phylogenetic analysis revealed that the isolate is Aspergillus flavus. Soybean and sunflower seedlings were inoculated with the identified A. flavus. The A. flavus-associated seedlings along with the control (without A. flavus) were monitored for thermal stress resistance in a growth chamber, operated at 25°C and 40°C. Control seedlings exposed to high temperature stress had higher levels of abscisic acid (ABA), proline, and lower levels of phenols, flavonoids, catalase, and ascorbic acid oxidase. Similarly, a higher reduction in chlorophyll, root-shoot length, and dry weight has been noticed in the control seedlings. The results suggested the usefulness of A. flavus in host plant growth promotion under heat stress conditions.

Performance of plant growth-promoting bacterium of duckweed under different kinds of abiotic stress factors

Abstract The effectiveness of a plant growth-promoting bacterium (PGPB) of duckweed, Aquitalea magnusonii H3, was studied under treatment with various abiotic stress factors repressing host plant growth (copper, zinc, salinity, weak light, low temperature, and nutrient scarcity). In the absence of stress factors, strain H3 stably improved the weekly yield of duckweed (Lemna minor) by 5.2–8.1% relative to aseptic control plants. However, in the presence of stress factors that reduced the duckweed weekly yield by approximately 40%, the performance of strain H3 changed both positively and negatively depending on the stress factor. Specifically, the growth promotion of strain H3 increased to 17.2% and 14.3% when the plant was subjected to copper and zinc stresses, respectively. Further evidence of increased plant accumulation of copper and zinc in the presence of strain H3 suggested that strain H3 enhanced the plant's capacity to both accumulate and tolerate these heavy metals. Conversely, the effects of strain H3 were inhibitory for duckweed growth under high salinity and nutrient-poor conditions. Additionally, other stress factors (weak light and low temperature) had no significant influence on PGPB performance. These results suggest that notably higher or lower performance of PGPB can be expressed under different kinds of plant stress factors.

Dark septate endophytes improve the growth of host and non-host plants under drought stress through altered root development

This study aimed to investigate how dark septate endophytes (DSE) from arid habitats affect host growth and their application to crops and medicinal plants in drought-prone soils. First, the osmotic-stress tolerance of Paraphoma sp., Embellisia chlamydospora, and Cladosporium oxysporum, isolated from Hedysarum scoparium, was tested using osmotically adjusted pure culture. Second, we examined the performance of host (H. scoparium) and non-host (Glycyrrhiza uralensis and Zea mays) plants inoculated with these fungi under mild (MD) and extreme drought (ED) conditions in a growth chamber. All the DSE showed high tolerance to osmotic stress in vitro and could colonise the roots of all the plants. For H. scoparium, DSE improved the root biomass and length depending on DSE species, with Paraphoma sp. and C. oxysporum exhibiting positive effects under all the drought treatments. For G. uralensis and Z. mays, DSE inoculation enhanced the root development of plants under MD condition and was dependent on the plant–fungus species. However, this positive effect was weakened under extreme drought stress. DSE isolated from H. scoparium enhanced the root growth of the host plant under drought conditions and may also be used to promote the cultivation of agricultural and medicinal plants.

The effects of co-colonising ectomycorrhizal fungi on mycorrhizal colonisation and sporocarp formation in Laccaria japonica colonising seedlings of Pinus densiflora

Forest trees are colonised by different species of ectomycorrhizal (ECM) fungi that interact competitively or mutualistically with one another. Most ECM fungi can produce sporocarps. To date, the effects of co-colonising fungal species on sporocarp formation in ECM fungi remain unknown. In this study, we examined host plant growth, mycorrhizal colonisation, and sporocarp formation when roots of Pinus densiflora are colonised by Laccaria japonica and three other ECM fungal species (Cenococcum geophilum, Pisolithus sp., and Suillus luteus). Sporocarp numbers were recorded throughout the experimental period. The biomass, photosynthetic rate, and mycorrhizal colonisation rate of the seedlings were also measured at 45days, 62days, and 1year after seedlings were transplanted. Results indicated that C. geophilum and S. luteus may negatively impact mycorrhizal colonisation and sporocarp formation in L. japonica. Sporocarp formation in L. japonica was positively correlated with conspecific mycorrhizal colonisation but negatively correlated with the biomass of seedlings of P. densiflora. The co-occurring ECM fungi largely competed with L. japonica, resulting in various effects on mycorrhizal colonisation and sporocarp formation in L. japonica. A variety of mechanisms may be involved in the competitive interactions among the different ECM fungal species, including abilities to more rapidly colonise root tips, acquire soil nutrients, or produce antibiotics. These mechanisms need to be confirmed in further studies.

Factors Influencing Leaf- and Root-Associated Communities of Bacteria and Fungi Across 33 Plant Orders in a Grassland.

In terrestrial ecosystems, plants interact with diverse taxonomic groups of bacteria and fungi in the phyllosphere and rhizosphere. Although recent studies based on high-throughput DNA sequencing have drastically increased our understanding of plant-associated microbiomes, we still have limited knowledge of how plant species in a species-rich community differ in their leaf and root microbiome compositions. In a cool-temperate semi-natural grassland in Japan, we compared leaf- and root-associated microbiomes across 137 plant species belonging to 33 plant orders. Based on the whole-microbiome inventory data, we analyzed how sampling season as well as the taxonomy, nativeness (native or alien), lifeform (herbaceous or woody), and mycorrhizal type of host plants could contribute to variation in microbiome compositions among co-occurring plant species. The data also allowed us to explore prokaryote and fungal lineages showing preferences for specific host characteristics. The list of microbial taxa showing significant host preferences involved those potentially having some impacts on survival, growth, or environmental resistance of host plants. Overall, this study provides a platform for understanding how plant and microbial communities are linked with each other at the ecosystem level.

Field and controlled conditions screenings of some faba bean (Vicia faba L.) genotypes for resistance to the parasitic plant Orobanche crenata Forsk. and investigation of involved resistance mechanisms

The parasitic weed Orobanche crenata is a serious constraint to legumes crops in Mediterranean area. In Morocco, heavy O. crenata infestation level was reported in many faba bean fields. Development of resistant faba bean genotypes remains a good long-term control strategy. So, identification of proper resistance sources remains a first step to attend this goal. In this perspective, six faba bean genotypes were subjected to field and controlled conditions (pot and Petri dishes experiments) evaluation for resistance/tolerance to Moroccan O. crenata. Root exudates and their implication on resistance/susceptibility to O. crenata were also investigated. Results showed a wide range of resistance but no complete resistance was detected. Thus, Giza 843, Misr1, and Misr3 genotypes showed good resistance level as compared to both susceptible genotypes Lobab and Aguadulce. Despite infection, the average yield of the three resistant genotypes was two to fourfold higher than the susceptible genotypes. Resistance of faba bean genotypes to O. crenata seems to occur at different levels of the parasite life cycle through: (1) developing lower host root density, (2) reduced attachment of O. crenata on host roots, and (3) delayed development of infection events on host roots. Furthermore, low induction of O. crenata seed germination could not be taken as an indicator of resistance. Based on low infection level and low impact of parasitism on yield and vegetative growth of host plants, Giza 843 was selected as a promising source of resistance to O. crenata which could be introduced into Moroccan faba bean breeding program.

Plant performance response to eight different types of symbiosis.

Almost all plant species interact with one or more symbioses somewhere within their distribution range. Bringing together plant trait data and growth responses to symbioses spanning 552 plant species, we provide for the first time on a large scale (597 studies) a quantitative synthesis on plant performance differences between eight major types of symbiosis, including mycorrhizas, N-fixing bacteria, fungal endophytes and ant-plant interactions. Frequency distributions of plant growth responses varied considerably between different types of symbiosis, in terms of both mean effect and 'risk', defined here as percentage of experiments reporting a negative effect of symbiosis on plants. Contrary to expectation, plant traits were poor predictors of growth response across and within all eight symbiotic associations. Our analysis showed no systematic additive effect when a host plant engaged in two functionally different symbioses. This synthesis suggests that plant species' ecological strategies have little effect in determining the influence of a symbiosis on host plant growth. Reliable quantification of differences in plant performance across symbioses will prove valuable for developing general hypotheses on how species become engaged in mutualisms without a guarantee of net returns.

Alleviation of salt stress and changes in glycyrrhizin accumulation by arbuscular mycorrhiza in liquorice (Glycyrrhiza glabra) grown under salinity stress

The symbiotically interaction of arbuscular mycorrhiza (AM) with liquorice (Glycyrrhiza glabra) which is widely used in traditional Iranian medicine, may have a good potential to enhance host plant growth and resistance to salt stress and may regulate the synthesis and accumulation pattern of secondary metabolites in plant tissues. The aims of this study were to assess the effect of AM fungus Funneliforms mosseae on liquorice plant's growth and nutrition, and the expression of important genes participated in the glycyrrhizin biosynthesis under salinity stress. The salinity stress induced a decreased trend in root fungal colonization, growth parameters, K and P concentrations and K+/Na+ ratios. Moreover, salinity caused a significant increase in electrolyte leakage and Na+ concentration in shoot and root of liquorice. AM colonization considerably increased P and K concentrations under salinity stress and promoted shoot proline accumulation and a higher K+/Na+ ratio and concentration of glycyrrhizin. The expression of three genes including beta-amyrin synthas (bAS), squalene synthase1 (SQS1) and P450 under different treatments were assessed by qRT-PCR. The highest increase in bAS and P450 gene expression was observed in stressed mycorrhizal plants. The expression of SQS1 was higher in stress condition compared to non-stressed plants. This study indicated the ameliorating effects of arbuscular mycorrhizal symbiosis in liquorice plant under salinity stress. The symbiosis of liquorice with AM fungi can be suggested as an alternative to enhance liquorice quality for pharmaceutical purposes and a practical approach for exploiting saline soils.

Colonization and Competition Dynamics of Plant Growth-Promoting/Inhibiting Bacteria in the Phytosphere of the Duckweed Lemna minor.

Despite the considerable role of aquatic plant-associated bacteria in host plant growth and nutrient cycling in aquatic environments, the mode of their plant colonization has hardly been understood. This study examined the colonization and competition dynamics of a plant growth-promoting bacterium (PGPB) and two plant growth-inhibiting bacteria (PGIB) in the aquatic plant Lemna minor (common duckweed). When inoculated separately to L. minor, each bacterial strain quickly colonized at approximately 106 cells per milligram (plant fresh weight) and kept similar populations throughout the 7-day cultivation time. The results of two-membered co-inoculation assays revealed that the PGPB strain Aquitalea magnusonii H3 consistently competitively excluded the PGIB strain Acinetobacter ursingii M3, and strain H3 co-existed at almost 1:1 proportion with another PGIB strain, Asticcacaulis excentricus M6, regardless of the inoculation ratios (99:1-1:99) and inoculation order. We also found that A. magnusonii H3 exerted its growth-promoting effect over the negative effects of the two PGIB strains even when only a small amount was inoculated, probably due to its excellent competitive colonization ability. These experimental results demonstrate that there is a constant ecological equilibrium state involved in the bacterial colonization of aquatic plants.

In Planta Screening of Maize Seed Endophytic Bacteria for Potential Applications under Dryland Conditions

Seeds harbor endophytic bacteria is capable of vertical transmission to next generation. These contribute to host plant's growth and adaptation to stress conditions. Such bacteria need to be developed for improving crop productivity. The present investigation was aimed at selecting promising maize seed endophytic bacteria (MSEB) for plant growth promotion under drought conditions through multilevel screening approach. Two levels of pot screening conducted using sterile soil helped in selecting eleven (out of eighty) promising isolates based on their positive influence on plant growth and biochemical parameters of maize under drought conditions. The third level pot screening was conducted using unsterile soil to evaluate the performance of selected 11 isolates under drought conditions. Pre-treatment of the seeds with MSEB isolates exhibited positive influence on plant growth and physiological parameters of maize under drought stress. Treatment with Corynebacterium hansenii MSEB 3 was found to be best in improving chlorophyll content (18.07%), relative water content (29.88%), and leaf proline (143.47%) besides improving other growth parameters over uninoculated control. Whereas, pretreatment with Bacillus subtilis MSEB 78 was found to be superior in improving shoot fresh weight (33.12%) and dry weight (54.36%) over control treatment. Significant positive correlations were observed between chlorophyll content and shoot fresh biomass, proline and relative water content, indicating its importance as a screening parameter for drought tolerance. Further, soil moisture content also showed significant positive correlation with shoot length, shoot fresh biomass and shoot dry biomass. The isolates selected in the present investigation can be exploited for agricultural benefits and can also add to the knowledge on plant-endophyte interactions under stress conditions.

Impact of an arbuscular mycorrhizal fungus on the growth and nutrition of fifteen crop and pasture plant species.

The formation of arbuscular mycorrhizas (AM) can result in positive, neutral or negative responses in the growth and mineral nutrition of host plants, particularly that of P, Zn and other micronutrients. This study examined the growth and nutritional responses of 15 agriculturally important plant species, including cereals, legumes and vegetables, with and without inoculation with the AM fungus (AMF) Rhizophagus irregularis. Furthermore, we explored whether the responses differed between different functional groups of plants such as monocots and dicots, C3 and C4 plants, and N-fixing and non-N-fixing plants. We found that that mycorrhizal colonisation of roots, plant growth and plant nutrient responses differed between plant species. Among the species analysed, leek (Allium ampeloprasum L. var. porrum) was the most mycorrhiza-responsive, displaying the highest mycorrhizal colonisation and biomass response, and the greatest increases in most mineral nutrients. In other plant species, the concentration of P, Cu, Zn and S were generally enhanced by inoculation with AMF. Furthermore, ionomes differed more greatly between plant species than in response to inoculation with AMF. This research further improves our understanding of the responses of different and diverse plant species to the formation of AM in terms of growth and ionomics under standardised growth conditions. The results of this study may be used in further studies and to inform agricultural practices.

Effects of mycorrhizae and water conditions on perennial ryegrass growth in rare earth tailings.

Mycorrhizal symbioses, which include plant roots and arbuscular mycorrhizal fungi (AMF), can significantly enhance plant resistance and promote the absorption of soil nutrients by plants. A greenhouse experiment was conducted to investigate the effects of three AMF species (Glomus mosses, Glomus etunicatum and Glomus versiforme) on the height, biomass, malondialdehyde (MDA) and proline contents and antioxidant enzyme activities of perennial ryegrass (Lolium perenne) under different water supply treatments. Potted experimental soil samples were collected from the abandoned rare earth tailings in Ganzhou, Jiangxi. The results showed that all three AMF species infected ryegrass under the different treatments. Under severe drought stress, G. mosses had the most significant effects on the promotion of ryegrass performance. After inoculation, the height and whole-plant biomass of ryegrass increased by 60.44% and 150%, respectively. In addition, inoculation with AMF significantly reduced the content of MDA and proline in the ryegrass leaves in all water supply treatments except the moderate drought stress treatment, in which there was no effect. The leaf antioxidant enzyme activity was also measured. The results showed that under severe drought stress, inoculation with Glomus mosses significantly increased the activities of CAT and SOD in ryegrass and enhanced the resistance of plants. A possible reason that AMF promotes host plant growth and enhances drought resistance is that AMF directly increases the absorption of soil water and minerals by host plant roots and indirectly improves the physiological metabolism of plants.