Shoot Phosphorus Content Research Articles

Improving Inoculum Production of Arbuscular Mycorrhizal Fungi in Zea mays L. Using Light-Emitting Diode (LED) Technology

A substrate-based production system is a simple and low-cost method for arbuscular mycorrhizal (AM) fungal inoculum production. However, it is time-consuming and typically yields low numbers of AM fungal spores due to several factors affecting plant growth efficiency. Our study investigated the use of light-emitting diode (LED) technology to expedite AM fungal spore production in planta. We performed experiments with Rhizophagus irregularis inoculated in maize (Zea mays L.), contrasting LED light with greenhouse (GH) conditions. Our results exhibited a significant improvement in AM fungal colonization and spore production, as well as a reduction in the production period from 120 to 90 days under the LED light condition. This was achieved using a red-and-blue light ratio of 60:40 with a total light intensity of 300 µmol m−2 s−1. The LED light treatments improved maize growth by increasing nitrogen (N) and phosphorus (P) concentrations in shoots and roots, respectively. Our gene expression analyses revealed that in AMF-inoculated plants, genes related to photosynthesis were significantly upregulated under LED light compared to the GH condition. Moreover, LED increased the expression of marker genes linked to the AM fungi-related cell cycle, indicating enhanced AM fungal growth during symbiosis. These findings advance our comprehension of LED applications in agriculture, offering promising prospects for acceleration of AM fungal spore production.

Responses of plant carbon, nitrogen, and phosphorus content in terrestrial ecosystems to warming: A Meta-analysis.

We conducted a Meta-analysis with 264 datasets from 55 publications to investigate the effects of warming duration and intensity on plant carbon, nitrogen and phosphorus contents. The results showed that warming significantly reduced shoot carbon (effect value of -1.7%), root carbon (-4.0%), litter carbon (-3.7%), shoot nitrogen (-7.0%) and litter nitrogen contents (-6.4%). For different ecosystem types, warming significantly decreased shoot carbon (-0.8%), shoot nitrogen (-5.9%), root carbon (-7.4%), litter carbon (-2.1%), and litter nitrogen content (-13.4%) in grasslands, while significantly increased shoot carbon (2.7%) in scrublands and litter phosphorus content (42.4%) in forests. Short-term warming (<5 years) decreased shoot carbon (-0.4%), shoot phosphorus (-0.4%) and litter nitrogen (-13.4%) contents, while medium- to long-term warming (5-10 years) increased shoot carbon (0.6%), shoot phosphorus (20.2%) and litter nitrogen (6.2%) contents. The 0-2 ℃ warming intensity increased shoot phosphorus (10.1%) and root phosphorus (27.4%) contents of plants, while the >2 ℃ warming intensity decreased shoot phosphorus (-3.7%) and root phosphorus (-6.5%) content. The effect values of plant shoot carbon and shoot nitrogen were significantly and positively correlated with humidity index. Warming showed negative effects on plant carbon, nitrogen and phosphorus contents in terrestrial ecosystems, and such effects were moderated by the duration and intensity of warming.

Nitrogen Nutrition-Induced Changes in Macronutrient Content and Their Indirect Effect on N-Metabolism Via an Impact on Key N-Assimilating Enzymes in Bread Wheat (Triticum aestivum L.)

Judicious application of nitrogen (N) fertilizers in crop production is critical for reducing the nitrate pollution of groundwater and greenhouse gas emissions. It is, thus, important to improve the nitrogen use efficiency under the reduced application of nitrogen. A genotypic variation in N-uptake and N-use efficiency particularly under low N-input conditions exists across crops that can be deciphered and exploited for environmentally sustainable farming without any significant penalty of yield and quality. The present research conducted under the nutrient solution culture aimed to explore the inherent variability in the growth response of ten genetically diverse wheat varieties to low fertilizer N-application (N-, 10 μM N) in comparison to N sufficient control (N+, 8.5 mM N) viz., a viz., the activity of various key N-assimilating enzymes and to delineate the indirect effect of low N on uptake and partitioning of other major macronutrients viz., P, K, S, which may indirectly regulate the N-use efficiency. A notable increase in sulfur, potassium, and phosphorus content was observed under nitrogen-deficient conditions. Varieties such as Carnamah and HD 2824 exhibit a significant increase in shoot phosphorus content, emphasizing their potential to optimize phosphorus acquisition and utilization efficiency under nutrient-limited conditions. The findings highlight the complex interplay between nutrient availability and plant responses, showcasing varietal-specific adaptations to nitrogen limitations.

Arbuscular mycorrhizal symbiosis with Rhizophagus irregularis DAOM197198 modifies the root transcriptome of walnut trees.

Walnut trees are cultivated and exploited worldwide for commercial timber and nut production. They are heterografted plants, with the rootstock selected to grow in different soil types and conditions and to provide the best anchorage, vigor, and resistance or tolerance to soil borne pests and diseases. However, no individual rootstock is tolerant of all factors that impact walnut production. In Europe, Juglans regia is mainly used as a rootstock. Like most terrestrial plants, walnut trees form arbuscular mycorrhizal symbioses, improving water and nutrient uptake and providing additional ecosystem services. Effects of arbuscular mycorrhizal symbiosis on root gene regulation, however, has never been assessed. We analyzed the response of one rootstock of J. regia to colonization by the arbuscular mycorrhizal fungus Rhizophagus irregularis DAOM197198. Plant growth as well as the nitrogen and phosphorus concentrations in roots and shoots were significantly increased in mycorrhizal plants versus non-colonized plants. In addition, we have shown that 1,549 genes were differentially expressed, with 832 and 717 genes up- and down-regulated, respectively. The analysis also revealed that some rootstock genes involved in plant nutrition through the mycorrhizal pathway, are regulated similarly as in other mycorrhizal woody species: Vitis vinifera and Populus trichocarpa. In addition, an enrichment analysis performed on GO and KEGG pathways revealed some regulation specific to J. regia (i.e., the juglone pathway). This analysis reinforces the role of arbuscular mycorrhizal symbiosis on root gene regulation and on the need to finely study the effects of diverse arbuscular mycorrhizal fungi on root gene regulation, but also of the scion on the functioning of an arbuscular mycorrhizal fungus in heterografted plants such as walnut tree.

A combination of biochemical fertilizers enhances plant nutrient absorption, water deficit tolerance, and yield of chickpea (Cicer arietinum L.) plants under irrigation regimes

Water shortage is the most critical abiotic stress and adversely impacts crop growth and productivity. Biofertilizers are an environmentally friendly method for sustainable agricultural development and improving plant water deficit tolerance. The effects of biological and chemical fertilizers on yield, yield components, and nutrient absorption of chickpea plants were studied in 2018 and 2019. The main plots were assigned to the irrigation levels [80% (I80) and 50% (I50)] and the subplot was assigned to 13 fertilizer combinations including free-living N-fixing bacteria (NB), potassium solubilizing bacteria (KB), phosphate solubilizing bacteria (PB), common chickpea nutrition program (F; NPK chemical fertilizer), and their combination. The results showed that shoot phosphorus content was increased by 80% when F + NPB (NPK chemical fertilizer and N + P biofertilizers) was applied at I80 compared with the control at I50. Furthermore, I80 and the application of PKB (P + K biofertilizers) and NPKB (N + P + K biofertilizers) obtained the highest shoot K and N concentrations, respectively. The NPKF + B-treated plants (N + P + K chemical fertilizer and N + P + K biofertilizers) demonstrated superior growth attributes such as plant height and the number of sub-branches at I80. The highest grain yield was obtained from the NPKF + B treatment at I80, which was 7.1-fold higher compared with the control at I50. In general, the combined application of biochemical fertilizers mitigated the adverse effect of water deficit and improved nutrient absorption and chickpea yield. The use of biochemical fertilizers can be efficient in reducing the consumption of chemical fertilizers and achieving sustainable agricultural goals.

Characteristics of the Rhizospheric AMF Community and Nutrient Contents of the Dominant Grasses in Four Microhabitats of the Subalpine Zone in Northwestern Yunnan, China

At the southeastern periphery of the Tibetan Plateau, the subalpine ecosystem hosts grasses as some of the most substantial species. However, the community and function of arbuscular mycorrhizal fungi (AMF) around the rhizospheres of grasses in the subalpine zone are still poorly understood. In the present study, 28 soils and 11 species of dominant grasses collected from four microhabitats (shrubland, grassland, woodland, and forest) in the subalpine zone of northwestern Yunnan, China, were used to investigate the AMF community by Illumina MiSeq high-throughput sequencing technology as well as nutrient contents. Among the four microhabitats, the maximum soil nutrient levels around the rhizospheres of grasses were observed in woodland. The nitrogen, phosphorus, and potassium concentrations in Dactylis glomerata shoots were significantly higher than those in the other 10 grass species. The AMF diversity of grassland in summer was substantially greater than that of the other three microhabitats (p &lt; 0.05). Discrepancies were observed within a given plant species across microhabitats; for example, in summer, the nitrogen concentration in the shoot of Iris tectorum in woodland was significantly higher than that in both forest and shrubland (p &lt; 0.05). A total of eight genera were detected in the AMF communities, which were dominated by Glomus, with a relative abundance of 45.4–94.4% in summer and 60.5–84.3% in winter. Moreover, the abundance of Glomus was significantly positively correlated with the content of alkali-hydrolyzable nitrogen in soil and nitrogen in grasses according to the Mantel test. As a critical nutrient element in soil, nitrogen is beneficial for plant growth. Thus, these results provide a better understanding of the resilience of soil AMF community and the ecological adaptability of grasses in the subalpine ecosystems of northwestern Yunnan.

Divergent colonization traits, convergent benefits: different species of arbuscular mycorrhizal fungi alleviate Meloidogyne incognita damage in tomato

Arbuscular mycorrhizal fungi (AMF) can increase plant tolerance and/or resistance to pests such as the root-knot nematode Meloidogyne incognita. However, the ameliorative effects may depend on AMF species. The aim of this work was therefore to evaluate whether four AMF species differentially affect plant performance in response to M. incognita infection. Tomato plants grown in greenhouse conditions were inoculated with four different AMF isolates (Claroideoglomus claroideum, Funneliformis mosseae, Gigaspora margarita, and Rhizophagus intraradices) and infected with 100 second stage juveniles of M. incognita at two different times: simultaneously or 2 weeks after the inoculation with AMF. After 60 days, the number of galls, egg masses, and reproduction factor of the nematodes were assessed along with plant biomass, phosphorus (P), and nitrogen concentrations in roots and shoots and root colonization by AMF. Only the simultaneous nematode inoculation without AMF caused a large reduction in plant shoot biomass, while all AMF species were able to ameliorate this effect and improve plant P uptake. The AMF isolates responded differently to the interaction with nematodes, either increasing the frequency of vesicles (C. claroideum) or reducing the number of arbuscules (F. mosseae and Gi. margarita). AMF inoculation did not decrease galls; however, it reduced the number of egg masses per gall in nematode simultaneous inoculation, except for C. claroideum. This work shows the importance of biotic stress alleviation associated with an improvement in P uptake and mediated by four different AMF species, irrespective of their fungal root colonization levels and specific interactions with the parasite.

Emergence and Early Growth of Four Desmanthus Species in Three Alkaline Clay Soils

Tropical pasture legumes such as Desmanthus are expected to improve pasture productivity in the extensive grazing systems of Northern Australia. However, the soils in these areas are often hostile (e.g., hard-setting and nutrient-deficient), which reduces legume emergence and establishment. Furthermore, these soils are often not ameliorated with amendments such as gypsum or starter fertilisers before planting. A pot trial was conducted to investigate differences in the emergence and early growth of four Desmanthus species. The legumes were grown in three alkaline clay soils that were unamended or amended with either gypsum (1 t CaSO4.2H2O ha−1 equivalent), a starter MAP fertiliser (12 kg P ha−1 equivalent), or both gypsum and the starter fertiliser. Seedling emergence was recorded daily and shoot yield was determined after six weeks’ growth. Final seedling emergence (as a percentage of viable seeds) varied among the Desmanthus species (c.f. D. leptophyllus = 63%, D. pernambucanus = 68%, D. bicornutus = 85%, and D. virgatus = 86%). On average, across the treatments, gypsum increased seedling emergence by 15%, whereas the starter fertiliser had no effect. The shoot yields and shoot phosphorus content of the Desmanthus species generally increased in response to the starter fertiliser. The collective results demonstrated that there were differences in emergence and early growth among the four Desmanthus species, which indicates that Desmanthus cultivar selection may be important in the relatively hostile soils of Northern Australia. Gypsum was an effective amendment for seedling emergence, whereas the starter fertiliser was an effective amendment to increase legume productivity.

Mitigation effects of Rhizophagus intraradices and Micrococcus yunnanensis on boron toxicity in maize (Zea may L.) plant

A greenhouse pot experiment was conducted to investigate the effect of arbuscular mycorrhiza fungus and plant growth promoting rhizobacterium on maize (Zea may L.) growth as well as nutrient concentrations under different levels of boron (B). Five levels of B (0, 10, 20, 40 and 60 mg B kg−1 as boric acid) and four levels of microbial inoculants (non-inoculation, Rhizophagus intraradices, Micrococcus yunnanensis, and co-inoculation) were used. Shoot and root dry weights significantly decreased as B levels increased. An increase in plant growth was observed at the levels of 10 and 20 mg B kg−1 due to microbial inoculation especially mycorrhization. Shoot and root dry weights positively correlated with shoot phosphorus concentration and root colonization. At the level of 40 mg B kg−1, root colonization significantly decreased. Shoot iron, copper, sodium and zinc concentrations significantly increased under excessive B concentrations. Totally, B application at low quantity improved plant growth while at higher rates it seemed toxic. Nonetheless, the inoculation of bacterium and arbuscular mycorrhiza had a more alleviative effect when the plant was exposed to excess B.

Some physio-biochemical traits of sunflower (&lt;em&gt;Helianthus annuus&lt;/em&gt; L.) as affected by arbuscular mycorrhizal fungi inoculation under different irrigation treatments

Plant-arbuscular mycorrhizal (AM) fungi association is one of the oldest symbiotic relationships between organisms. This relationship may be more important under stress conditions such as drought and can help the host plant tolerate drought. This study was conducted in 2016 and 2017 at the Agricultural Research Farm of Razi University, Kermanshah, Iran to evaluate the effect of AM fungi (AMF) inoculation (with either Funneliformis mosseae or Rhizophagus intraradices) on some physio-biochemical traits of three sunflower cultivars under different soil irrigation treatments (severe water deficit stress, mild water deficit stress and well-watered). In both years, water deficit conditions significantly reduced leaf relative water content (RWC), chlorophyll concentrations (a, b and total) and shoot phosphorus concentration (SPC) while simultaneously increasing shoot proline levels and malondialdehyde (MDA) concentrations. AMF inoculation had positive effects on RWC, chlorophyll concentrations and SPC irrespective of sunflower cultivar and irrigation treatment. Shoot proline concentration and MDA reduced more in AM than non-AM plants. In most cases F. mosseae performed better than R. intraradices in terms of plant performance. Moreover, the improvements caused by AM fungi were more evident under water deficit than well-watered condition. It may be concluded that AM inoculation can alleviate the negative effects of water deficit stress on some important physio-biochemical traits of sunflower grown in the field, and can be considered as a practical and economical approach to improve crop performance in environments exposed to water limitations.

Overexpression of soybean microRNA156b enhanced tolerance to phosphorus deficiency and seed yield in Arabidopsis

microRNAs (miRNAs) are endogenous small RNAs that are key regulatory factors participating in various biological activities such as the signaling of phosphorus deficiency in the plant. Previous studies have shown that miR156 expression was modulated by phosphorus starvation in Arabidopsis and soybean. However, it is not clear whether the over-expression of soybean miR156b (GmmiR156b) can improve a plant’s tolerance to phosphorus deficiency and affect yield component traits. In this study, we generated Arabidopsis transgenic lines overexpressing GmmiR156b and investigated the plant’s response to phosphorus deficiency. Compared with the wild type, the transgenic Arabidopsis seedlings had longer primary roots and higher phosphorus contents in roots under phosphorus-deficit conditions, but lower fresh weight root/shoot ratios under either phosphorus-deficient or sufficient conditions. Moreover, the GmmiR156b overexpression transgenic lines had higher phosphorus content in shoots of adult plants and grew better than the wide type under phosphorus-deficient conditions, and exhibited increased seed yields as well as strong pleiotropic developmental morphology such as dwarfness, prolonged growth period, bushy shoot/branching, and shorter silique length, suggesting that the transgenic lines were more tolerant to phosphorus deficiency. In addition, the expression level of four SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) genes (i.e., AtSPL4/5/6/15) were markedly suppressed in transgenic plants, indicating that they were the main targets negatively regulated by GmmiR156b (especially AtSPL15) and that the enhanced tolerance to phosphorus deficiency and seed yield is conferred mainly by the miR156-mediated downregulation of AtSPL15.

Native Arbuscular Mycorrhizal Inoculum Modulates Growth, Oxidative Metabolism and Alleviates Salinity Stresses in Legume Species.

Soil salinity constitutes a major abiotic stress that contributes to soil degradation and crop yield reduction. Using arbuscular mycorrhizal fungi (AMF) inoculation can help to alleviate these deleterious effects. Most researches on AMF application are dealing with ecological restoration, whereas little consideration has been given to agriculture and legume production. The comparison of the efficacy of two AMF inoculums, one native originating from Algerian semiarid saline soils and one commercial inoculum, was carried out regarding their effects on the growth and the mineral nutrition of several legumes species, Medicago sativa, Medicago falcata, Trifolium repens and Trifolium alexandrinum, cultivated in semiarid Algerian saline soil under greenhouse conditions. Our results showed that native mycorrhizal inoculum enhanced shoot biomasses by 20%, mycorrhizal rate by 30%, shoot phosphorus content by 25% and K+/Na+ ratio by 45% for studied plants when compared with commercial inoculum. The best efficiency of the native AMF inoculum is probably due to the complementarity between the AMF strains which composed the inoculum. Funneliformis geosporum was the most abundant species recorded at the end of the experience in all plant roots especially with native inoculum. Our findings pointed out the effectiveness of native AMF inoculum application to promote agricultural production in semiarid saline soils.

Critical shoot phosphorus concentrations for changes in root morphology to improve phosphorus uptake in cotton

AbstractBackgroundIn recent years, the response of cotton (Gossypium hirsutum L.) root morphology and rhizosphere processes to phosphorus (P) deficiency have attracted extensive attention. However, the dynamics of root morphology and physiology to shoot P concentration (SPC) under various P conditions remain unclear.AimWe aimed to determine the changes in root morphology and physiology and their relationships with SPC under different levels of P supply.MethodThe cotton cultivars XLZ13 and XLZ19 were grown in a hydroponic experiment with seven rates of P supply (0–2.0 mM P L−1) and in a root box experiment with seven P levels (0–400 mg P kg−1). Root morphological and physiological parameters were determined 60 days after planting (hydroponic experiment) and 75 days after transplanting (root box experiment).ResultsCotton plant growth, P uptake, and root morphology differed significantly between the two genotypes and among the P levels. Cotton plants had the maximum shoot biomass when the SPC of XLZ13 and XLZ19 were 4.6–5.9 mg g−1 and 3.9‐5.0 mg g−1, respectively. Total and specific root lengths initially increased with increasing SPC and peaked at an SPC of XLZ13 and XLZ19 about 6.0–7.0 mg g−1 and 4.0‐5.0 mg g−1, respectively. Root physiological responses (rhizosphere acidification, acid phosphatase [Apase] activity) decreased as the SPC increased.ConclusionsThe critical SPC for optimal root morphology were 5–6 mg g−1. P deficiency did not induce rhizosphere acidification but promoted root and rhizosphere APase activity.

Eficiência de uso de fósforo por genótipos de meloeiro

ABSTRACT This study aimed to evaluate the efficiency of phosphorus use with melon genotypes cultivated in a hydroponic system. Ten melon genotypes were evaluated in solutions with and without phosphorus restriction. A randomized block design in a 10 × 2 factorial scheme was used, with five replicates. The following characteristics were evaluated: leaf number, stem diameter, main branch length, root system length, root system volume, chlorophyll, root and shoot phosphorus concentration ratio, total phosphorus, root and shoot dry matter ratio, total dry matter, and phosphorus use, acquisition, and internal utilization efficiencies. The existence of variability among genotypes was verified for all evaluated characteristics, except for chlorophyll. Genotypes A-16, A-29, A-50, A-52, and Trinity were classified as efficient and responsive in the phosphorus-restricted solution and are promising for breeding studies.

Evaluation of the performance of some cultivars of Faba Bean Vicia faba L. under different levels of phosphorus

A field experiment was carried out during winter season of 2021-2022 to study growth and yield performance of four faba bean cultivars (lo-cal, Spanish, Dutch and New Zealand) and evaluate their performance under three levels of phosphorus fertilizer (80, 120 and 160 kg ha-1). The experiment was applied in split plot design with three replications. results showed highly significant effects of fertilization on all measured traits, as the third level (160 kg ha-1) superior in all measured traits, and gave plant dry weight (171.33 g) and seed yield (4.403 Mg ha-1). local cultivar was superior in traits: plant height, total phosphorus content, phosphorus use efficiency and plant dry weight. As for New Zealand cultivar excelled in: number of branches, number of leaves, and phosphorus concentration in shoot. while Spanish cultivar was superior in total seed yield (5.295 Mg ha-1).

Cocoa Clones Reveal Variation in Plant Biomass, Root Nitrogen Uptake, and Apparent Nitrogen Recovery at the Seedling Stage

We aimed to investigate variation in growth, biomass, macro-nutrient uptake, and nitrogen (N) use efficiency indices of cocoa (Theobroma cocoa L.) scion clones under two different nitrogen conditions. Ten clones were top-grafted onto 4-month-old rootstocks clone MCC 02. Each seedling received either 0 or 4.6 g of nitrogen applied as urea fertilizer. The design was arranged as a two-factor experiment with four replicates in a factorial randomized block design. We measured stem diameter, biomass, nutrient concentration, and calculated nutrient uptake, nitrogen use efficiency (NUE), agronomic efficiency (AE), apparent nitrogen recovery (ANR), and physiological efficiency (PE). We found that clones significantly affected stem diameter and shoot biomass of both rootstocks and scions. Clones differed in root magnesium (Mg) and shoot calcium (Ca) concentration, root N, and shoot Mg uptake. Furthermore, a significant clone effect was observed on ANR, with local clones showing higher ANR than introduced clones. Nitrogen application significantly improved stem diameter and biomass. Compared to unfertilized plants, a significantly higher N concentration was observed in roots, resulting in higher N uptake in both roots and shoots. Nitrogen application increased shoot Ca concentration and uptake but decreased shoot phosphorus (P) and Mg concentrations. Our results suggest genotypic variability in nitrogen uptake efficiency in clonal cocoa. Clones with high nitrogen uptake efficiency are valuable genetic resources for breeding cocoa clones that efficiently use available N and, therefore, grow better under N-deficient conditions.

Variation in mycorrhizal growth response among a spring wheat mapping population shows potential to breed for symbiotic benefit.

All cereal crops engage in arbuscular mycorrhizal symbioses which can have profound, but sometimes deleterious, effects on plant nutrient acquisition and growth. The mechanisms underlying variable mycorrhizal responsiveness in cereals are not well characterised or understood. Adapting crops to realise mycorrhizal benefits could reduce fertiliser requirements and improve crop nutrition where fertiliser is unavailable. We conducted a phenotype screen in wheat (Triticum aestivum L.), using 99 lines of an Avalon × Cadenza doubled‐haploid mapping population. Plants were grown with or without a mixed inoculum containing 5 species of arbuscular mycorrhizal fungi. Plant growth, nutrition and mycorrhizal colonisation were quantified. Plant growth response to inoculation was remarkably varied among lines, ranging from more than 30% decrease to 80% increase in shoot biomass. Mycorrhizal plants did not suffer decreasing shoot phosphorus concentration with increasing biomass as observed in their non‐mycorrhizal counterparts. The extent to which mycorrhizal inoculation was beneficial for individual lines was negatively correlated with shoot biomass in the non‐mycorrhizal state but was not correlated with the extent of mycorrhizal colonisation of roots. Highly variable mycorrhizal responsiveness among closely related wheat lines and the identification of several QTL for these traits suggests the potential to breed for improved crop‐mycorrhizal symbiosis.

Loss of fungal symbionts at the arid limit of the distribution range in a native Patagonian grass—Resource eco‐physiological relations

Abstract Crucial to our understanding of plant ecology is the consideration of the eco‐physiological responses and constraints of plant–fungal symbioses throughout the native distribution range of their host. We examined key eco‐physiological roles of two co‐occurring fungal symbionts [Epichloë endophytes and arbuscular mycorrhizal fungi (AMF)] in the endemic grass Hordeum comosum across a wide bioclimatic gradient and contrasting grazing severity. We sampled H. comosum plants along four humid‐to‐arid transects in Patagonia, Argentina, covering its entire distribution range and determined Epichloë presence, AMF root colonization, nitrogen and phosphorus concentration, intrinsic water‐use efficiency (iWUE, the ratio of photosynthesis to stomatal conductance) and 18O‐enrichment of cellulose in shoots. Root colonization by AMF increased with Epichloë presence. All plants hosted Epichloë in the humid range of the gradient, but symbioses occurrence decreased towards arid sites which also displayed severe grazing symptoms at site level. Symbiosis with Epichloë correlated positively with shoot nitrogen concentration in the centre of the distribution range, and with shoot phosphorus concentration across the entire distribution range. The site‐level relationship of AMF colonization with 18O‐enrichment and iWUE suggested that mycorrhiza boosted stomatal conductance in humid environments but curbed it in arid environments. While the interpretation of interactions and potential causalities from observational studies should be done with caution, this study demonstrates distinct correlations between plant–fungal symbiont associations and key resource parameters (phosphorus, nitrogen and iWUE vs. 18O‐enrichment). Such correlations may suggest particular functional roles for these symbionts in the ecology of their host plant. A free Plain Language Summary can be found within the Supporting Information of this article.

Breeding Practice Improves the Mycorrhizal Responsiveness of Cotton (Gossypium spp. L.).

Maximizing the function of indigenous arbuscular mycorrhizal (AM) fungi by choosing specific crop genotypes offers one of the few untapped opportunities to improve the sustainability of agriculture. In this study, the differences in mycorrhizal responsiveness (MR) in plant growth and shoot phosphorus (P) content among cotton (Gossypium spp. L.) genotypes from different release dates were compared and then the relationships between MR and P uptake-related traits were determined. The experimental design in a greenhouse included 24 genotypes released from 1950 to present in Xinjiang Province, inoculation with or without AM fungi, and P levels (15 and 150 mg P kg–1 added as KH2PO4). Results showed that the modern cotton genotypes exhibited a higher degree of mycorrhizal colonization, the hyphal length density (HLD), and mycorrhizae-induced changes in shoot growth than the old genotypes when inoculated with indigenous AM fungi at both the P levels. Moreover, MR was highly correlated with the HLD at low P levels and the HLD may provide useful insights for future cotton breeding aimed at delivering crop genotypes that can benefit more from AM fungi.

Inoculum Sources Modulate Mycorrhizal Inoculation Effect on Tamarix&nbsp;articulata Development and Its Associated Rhizosphere Microbiota.

(1) Background: Soil degradation is an increasingly important problem in many parts of the world, particularly in arid and semiarid areas. Arbuscular mycorrhizal fungi (AMF) isolated from arid soils are recognized to be better adapted to these edaphoclimatic conditions than exogenous ones. Nevertheless, little is known about the importance of AMF inoculum sources on Tamarix articulata development in natural saline soils. Therefore, the current study aims at investigating the efficiency of two AMF-mixed inoculums on T. articulata growth, with consideration of its rhizosphere microbiota. (2) Methods: indigenous inoculum made of strains originating from saline soils and a commercial one were used to inoculate T. articulata in four saline soils with different salinity levels under microcosm conditions with evaluation of rhizosphere microbial biomasses. (3) Results: Our findings showed that indigenous inoculum outperforms the commercial one by 80% for the mycorrhizal rate and 40% for plant biomasses, which are correlated with increasing shoot phosphorus content. Soil microbial biomasses increased significantly with indigenous mycorrhizal inoculum in the most saline soil with 46% for AMF, 25% for saprotrophic fungi and 15% for bacterial biomasses. (4) Conclusion: Present results open the way towards the preferential use of mycorrhizal inoculum, based on native AMF, to perform revegetation and to restore the saline soil microbiota.