RESUMO
The antagonistic interplay between phosphorus (P) and zinc (Zn) in plants is well established. However, the molecular mechanisms mediating those interactions as influenced by arbuscular mycorrhizal (AM) symbiosis remain unclear. We investigated Zn concentrations, root AM symbiosis, and transcriptome profiles of maize roots grown under field conditions upon different P levels. We also validated genotype-dependent P-Zn uptake in selected genotypes from a MAGIC population and conducted mycorrhizal inoculation experiments using mycorrhizal-defective mutant pht1;6 to elucidate the significance of AM symbiosis in P-Zn antagonism. Finally, we assessed how P supply affects Zn transporters and Zn uptake in extraradical hyphae within a three-compartment system. Elevated P levels led to a significant reduction in maize Zn concentration across the population, correlating with a marked decline in AM symbiosis, thus elucidating the P-Zn antagonism. We also identified ZmPht1;6 is crucial for AM symbiosis and confirmed that P-Zn antagonistic uptake is dependent on AM symbiosis. Moreover, we found that high P suppressed the expression of the fungal RiZRT1 and RiZnT1 genes, potentially impacting hyphal Zn uptake. We conclude that high P exerts systemic regulation over root and AM hyphae-mediated Zn uptake in maize. These findings hold implications for breeding Zn deficiency-tolerant maize varieties.
Assuntos
Regulação da Expressão Gênica de Plantas , Micorrizas , Fósforo , Solo , Simbiose , Zea mays , Zinco , Zea mays/microbiologia , Zea mays/metabolismo , Zea mays/genética , Micorrizas/fisiologia , Zinco/metabolismo , Fósforo/metabolismo , Solo/química , Transporte Biológico , Raízes de Plantas/microbiologia , Raízes de Plantas/metabolismo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/genética , Hifas , Genótipo , Mutação/genéticaRESUMO
Although the interaction between P and Zn has long been recognized in plants, the physiological and molecular mechanisms underlying P and Zn interactions are poorly understood. We show here that P supply decreases the Zn concentration in maize shoots and roots. Compared to +P + Zn (addition of both P and Zn), +P-Zn reduced and -P-Zn increased the total length of 1° lateral roots (LRs). Under +P + Zn, both P and Zn concentrations were lower in the sl1 mutant roots than in wild-type (WT) maize roots, and P accumulation did not reduce the Zn concentration in ll1 mutant roots. Transcriptome profiling showed that the auxin signaling pathway contributed to P-mediated Zn homeostasis in maize. Auxin production and distribution were altered by changes in P and Zn supply. Cytosolic Zn co-localized with auxin accumulation under +P + Zn. Exogenous application of 1-NAA and L-Kyn altered the P-mediated root system architecture (RSA) under Zn deficiency. -P-Zn repressed the expression of miR167. Overexpression of ZmMIR167b increased the lengths of 1° LRs and the concentrations of P and Zn in maize. These results indicate that auxin-dependent RSA is important for P-mediated Zn homeostasis in maize.HighlightAuxin-dependent RSA is important for P-mediated Zn homeostasis in maize.
Assuntos
Fósforo , Zea mays , Fósforo/metabolismo , Zea mays/metabolismo , Raízes de Plantas/metabolismo , Ácidos Indolacéticos/metabolismo , Homeostase , Zinco/metabolismo , Transdução de SinaisRESUMO
High-quality products in sustainable agriculture require both limited health risks and sufficient dietary nutrients. Phosphorus (P) as a finite and non-renewable resource is widely used in agriculture, usually exerting influence on the accumulation of heavy metals (HMs) in soil and crops. The present research explores, for the first time, the combined effects of long-term P fertilizer and repeated zinc (Zn) application in field on the human health risks and nutritional yield regarding trace elements in maize grain. A field experiment was conducted using maize with six P application rates (0, 12.5, 25, 50, 100, and 200 kg P ha-1) and two Zn application rates (0 and 11.4 kg Zn ha-1). The results showed that the concentrations of Zn, copper (Cu), and lead (Pb) in the maize grain were significantly affected by P application and can be further affected by Zn application. The concentrations of chromium (Cr) and arsenic (As) showed opposite tendency as affected by P fertilizer rates while did not affected by additional Zn application. Zn application decreased the cadmium (Cd) concentration at high P levels and Pb concentration at low P levels, particularly. No HMs contamination or direct health risk was found in maize grain after receiving long-term P and repeated Zn fertilizer. The threshold hazard quotient of an individual and all investigated HMs in this study were acceptable for human digestion of maize grain. While the carcinogenic risk of Cr was non-negligible in case of maize was taken as one of daily staple food for local residents. Combination use of P (25 kg ha-1) and Zn fertilizer on maize enhanced its nutritional supply ability regarding Zn and Cu, and simultaneously mitigated potential human health risks associated with Cd and Pb.
Assuntos
Metais Pesados , Poluentes do Solo , Agricultura , China , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Metais Pesados/toxicidade , Fósforo , Medição de Risco , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Zea maysRESUMO
The possible potential application of Fe-NPs on Fe nutrition, heavy metals uptake and soil microbial community needs to be investigated. In the current research, a pot experiment was used to examine the implications of Fe-NPs (α-Fe2O3 and Fe3O4) on maize growth, Fe uptake and transportation, soil microbial community, and environmental risk. Fe3O4, α-Fe2O3, FeSO4 at a rate of 800 mg Fe kg-1 were applied in soils with four replications under a completely randomized design for a period of 60 days. Results showed that Fe uptake by maize roots were increased by 107-132% than control, with obvious variations across different treatments (Fe3O4> α-Fe2O3> FeSO4> control). Similarly, plant height, leaf surface area, and biomass were increased by 40-64%, 52-91% and 38-109% respectively, with lower values by FeSO4 application. The elevated level of chlorophyll contents and carotenoids and significant effects with control on antioxidant enzymes activities (i.e., catalase, and superoxide dismutase) suggested that application of Fe-NPs improved overall biochemical processes. The differential expression of important Fe transporters (i.e., ZmYS1 and ZmFER1) as compared to control indicated the plant strategic response for efficient uptake and distribution of Fe. Importantly, Fe-NPs reduced the heavy metals uptake (i.e., chromium, cadmium, arsenic, nickel, copper) by complex formation, and showed no toxicity to the soil microbial community. In summary, the application of Fe-NPs can be a promising approach for improving crop productivity and Fe nutrition without negatively affecting soil microbial community, and fostering sustainable agricultural production.
Assuntos
Compostos Férricos , Ferro , Poluentes do Solo , Zea mays , Zea mays/crescimento & desenvolvimento , Zea mays/efeitos dos fármacos , Zea mays/metabolismo , Compostos Férricos/química , Ferro/metabolismo , Solo/química , Microbiologia do Solo , Raízes de Plantas/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/efeitos dos fármacos , Metais Pesados/metabolismo , Clorofila/metabolismo , Nanopartículas de Magnetita/químicaRESUMO
BACKGROUND: Beneficial associations between plants and soil microorganisms are critical for crop fitness and resilience. However, it remains obscure how microorganisms are assembled across different root compartments and to what extent such recruited microbiomes determine crop performance. Here, we surveyed the root transcriptome and the root and rhizosphere microbiome via RNA sequencing and full-length (V1-V9) 16S rRNA gene sequencing from genetically distinct monogenic root mutants of maize (Zea mays L.) under different nutrient-limiting conditions. RESULTS: Overall transcriptome and microbiome display a clear assembly pattern across the compartments, i.e., from the soil through the rhizosphere to the root tissues. Co-variation analysis identified that genotype dominated the effect on the microbial community and gene expression over the nutrient stress conditions. Integrated transcriptomic and microbial analyses demonstrated that mutations affecting lateral root development had the largest effect on host gene expression and microbiome assembly, as compared to mutations affecting other root types. Cooccurrence and trans-kingdom network association analysis demonstrated that the keystone bacterial taxon Massilia (Oxalobacteraceae) is associated with root functional genes involved in flowering time and overall plant biomass. We further observed that the developmental stage drives the differentiation of the rhizosphere microbial assembly, especially the associations of the keystone bacteria Massilia with functional genes in reproduction. Taking advantage of microbial inoculation experiments using a maize early flowering mutant, we confirmed that Massilia-driven maize growth promotion indeed depends on flowering time. CONCLUSION: We conclude that specific microbiota supporting lateral root formation could enhance crop performance by mediating functional gene expression underlying plant flowering time in maize. Video Abstract.
Assuntos
Flores , Microbiota , Raízes de Plantas , RNA Ribossômico 16S , Rizosfera , Microbiologia do Solo , Zea mays , Zea mays/microbiologia , Zea mays/genética , Raízes de Plantas/microbiologia , Flores/microbiologia , Flores/crescimento & desenvolvimento , RNA Ribossômico 16S/genética , Transcriptoma , Mutação , Regulação da Expressão Gênica de PlantasRESUMO
Pepper (Capsicum spp.) is an important fruit vegetable worldwide, and it is a rich dietary source of minerals for human being. Yet, the spatio-temporal distribution of pepper fruit mineral composition and the factors influencing such variations at global scale remain unknown. A global meta-analysis of 140 publications providing 649, 562, 690, 811 datapoints was conducted to quantify and evaluate the nutritional quality, comprising potassium (K), magnesium (Mg), iron (Fe) and zinc (Zn), of pepper fruits and its influencing variables. The analysis showed that the global average of K, Mg, Fe and Zn content in pepper fruits was 20-25 g kg-1, 1-1.5 g kg-1, 80-100 mg kg-1, and 20-40 mg kg-1, respectively. There had been a downward trend in pepper fruit nutritional quality over the last decade, especially for Fe and Zn. And, the concentration of all these four nutrients were at lower levels in less developed regions, especially in Africa. Our results showed that the vegetable "green pepper" contains more K, Mg, Fe and Zn than the "hot pepper" used as spice. The concentration of K, Mg, Fe and Zn were increased with fruit yield but that of Fe and Zn were decreased with increase in single fruit weight. Nutritional quality was optimal at mean annual temperature of 10 â - 20 â, and was adversely affected when mean annual precipitation was < 500 mm. Pepper fruits produced at pH 6.5-7.5 had higher fruit K concentration while acidic soils (pH<6.5) favored higher Fe and Zn concentrations. The higher soil organic matter (SOM) generally improved the nutritional quality of the pepper. Our results suggest that systematic selection of superior varieties and soil amelioration (adjusting pH and SOM) of the soil-crop system are needed to achieve higher nutritional quality of pepper fruit.
Assuntos
Capsicum , Frutas , Valor Nutritivo , Capsicum/química , Frutas/química , Minerais/análise , Análise Espaço-Temporal , Potássio/análise , Magnésio/análise , Zinco/análise , Ferro/análiseRESUMO
In sustainable agriculture, sufficient crop yields and nutrients must be produced while maintaining environmental protection. Considering the role of phosphorus (P) fertilizer in influencing crops yield and environmental security, life cycle assessment was used to examine the environmental impacts of long-term P application on the grain yield and nutritional quality of winter wheat and summer maize. Thus, a long-term field experiment with six P application rates for winter wheat (0, 25, 50, 100, 200, and 400 kg P ha-1) and summer maize (0, 12.5, 25, 50, 100, and 200 kg P ha-1) was conducted on the North China Plain (NCP). The results showed that the cradle-to-farm gate eutrophication potential (EP), energy depletion (ED), and P depletion (PD) were significantly affected by the P application rate applied in winter wheat and summer maize production. The critical P rate required to ensure food security for wheat and maize was in line with the optimal rate for sustainable environmental development in terms of grain production and nutrient levels. On the NCP, the ED and PD of summer maize with optimized P management over 10 years were less than those of winter wheat regardless of using yield or nutrient level as the functional unit. However, the EP of the nutrient supply in winter wheat was less than that in summer maize under optimized P fertilization. The specific nutritional components that limited improvements in environment of wheat and maize production under the optimal P rate were energy (calories) and protein, respectively. In conclusion, in a multifunctional winter wheat-summer maize rotation system, optimized P fertilization (50 kg ha-1 for winter wheat and 25 kg ha-1 for summer maize) combined with the planting of high-yield wheat varieties and high-protein maize varieties showed great potential to reduce the environmental impacts of wheat and maize production.
Assuntos
Triticum , Zea mays , Agricultura , Animais , China , Fertilizantes , Estágios do Ciclo de Vida , Nitrogênio/análise , Rotação , SoloRESUMO
Zinc (Zn) malnutrition is a common health problem, especially in developing countries. The human health and economic benefits of the replacement of conventional flour with Zn-biofortified wheat flour in rural household diets were assessed. One hundred forty-five wheat flour samples were collected from rural households in Quzhou County. Then, field experiments were conducted on wheat at two Zn levels (0 and 0.4% ZnSO4 · 7H2O foliar application) under 16 diverse agricultural practices in Quzhou County. Foliar Zn application significantly increased the Zn concentration and bioavailability in wheat grain and flour. If rural households consumed Zn-biofortified flour instead of self-cultivated flour or flour purchased from supermarkets, 257-769 or 280-838, 0.46-1.36 million or 0.50-1.49 million disability-adjusted life years (DALYs) lost, respectively, could be saved in Quzhou County and China. Amounts of 2.3-12.0 million and 5.5-22.6 billion RMB could be obtained via Zn-biofortified flour in Quzhou County and China, respectively. The current study indicates that Zn-biofortified flour via foliar Zn application is a win-win strategy to maintain the yield and combat human Zn deficiency in rural households in China. More health and economic benefits could be obtained in rural household dependent on wheat flour purchased from supermarkets than in those dependent on self-cultivated wheat flour.
RESUMO
Negative effects of high phosphorus (P) application on zinc (Zn) nutrition have been observed in many crops. This study investigated the Zn responses of three typical crops to varied P and Zn applications. A pot experiment was conducted using two mycorrhizal crops (maize and soybean) and one non-mycorrhizal crop (oilseed rape) under three levels of P, two levels of Zn, and two levels of benomyl. Results showed that P application significantly decreased shoot and root Zn concentrations, Zn uptake, and Zn acquisition efficiency (ZnAE) of the three crops irrespective of Zn rate, and that these reductions were greater for maize and soybean than for oilseed rape. Zn application alleviated the P inhibition of Zn uptake in the three crops. The arbuscular mycorrhizal fungi (AMF) colonization of maize and soybean contributed most to the negative effects of increasing P application on Zn uptake, explaining 79-89 and 64-69% of the effect, respectively. For oilseed rape, root dry weight and root Zn concentration explained 90% of the decrease in Zn uptake caused by P application. These results suggest that there is another pathway in addition to the mycorrhizal pathway regulating Zn uptake under mediation by P supply.
RESUMO
Zinc (Zn) fertilizer application can certainly improve the production and nutritional quality of cereal crops. However, Zn accumulation in the soil may lead to some deleterious environmental impacts in agroecosystems. The effects of long-term Zn application on soil microbial properties remain unclear, but it is imperative to understand such effects. In this study, we collected soil samples from a nine-year field experiment in a wheat-maize system that continuously received Zn applied at various rates (0, 2.3, 5.7, 11.4, 22.7 and 34.1 kg ha-1) to evaluate the soil enzymes, microbial biomass and microbial community structure. The results showed that Zn application at the rate of 5.7 kg ha-1 significantly increased the activities of urease, invertase, alkaline phosphatase and catalase in the soil, while the rate of 34.1 kg ha-1 significantly decreased the evaluated enzyme activities. The microbial biomass carbon (C) and nitrogen (N) were not affected by Zn application rates, although an increase in the microbial biomass C was observed in the 11.4 kg ha-1 treatment. Moreover, the alpha diversity of the bacterial and fungal communities did not vary among the nil Zn, optimal Zn (5.7 kg ha-1) and excess Zn (34.1 kg ha-1) treatments. However, the bacterial communities in the soil receiving the optimal and excess Zn application rates were slightly changed. Compared to the nil Zn treatment, the other Zn application rates increased the relative abundances of the Rhodospirillales, Gaiellales and Frankiales orders and decreased the abundance of the Latescibacteria phylum. The redundancy analysis further indicated that the soil bacterial community composition significantly correlated with the concentrations of soil DTPA-Zn and total Zn. These results highlight the importance of optimal Zn application in achieving high production and high grain quality while concurrently promoting soil microbial activity, improving the bacterial community and further maintaining the sustainability of the agroecological environment.