Wheat Rhizosphere Metagenome Reveals Newfound Potential Soil Zn-Mobilizing Bacteria Contributing to Cultivars’ Variation in Grain Zn Concentration

An effective solution to global human zinc (Zn) deficiency is Zn biofortification of staple food crops, which has been hindered by the low available Zn in calcareous soils worldwide. Many culturable soil microbes have been reported to increase Zn availability in the laboratory, while the status of these microbes in fields and whether there are unculturable Zn-mobilizing microbes remain unexplored. Here, we use the culture-independent metagenomic sequencing to investigate the rhizosphere microbiome of three high-Zn (HZn) and three low-Zn (LZn) wheat cultivars in a field experiment with calcareous soils. The average grain Zn concentration of HZn was higher than the Zn biofortification target 40 mg kg–1, while that of LZn was lower than 40 mg kg–1. Metagenomic sequencing and analysis showed large microbiome difference between wheat rhizosphere and bulk soil but small difference between HZn and LZn. Most of the rhizosphere-enriched microbes in HZn and LZn were in common, including many of the previously reported soil Zn-mobilizing microbes. Notably, 30 of the 32 rhizosphere-enriched species exhibiting different abundances between HZn and LZn possess the functional genes involved in soil Zn mobilization, especially the synthesis and exudation of organic acids and siderophores. Most of the abundant potential Zn-mobilizing species were positively correlated with grain Zn concentration and formed a module with strong interspecies relations in the co-occurrence network of abundant rhizosphere-enriched microbes. The potential Zn-mobilizing species, especially Massilia and Pseudomonas, may contribute to the cultivars’ variation in grain Zn concentration, and they deserve further investigation in future studies on Zn biofortification.

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IRRIGATION MANAGEMENT RISKS AND ZN FERTILIZATION NEEDS IN ZN BIOFORTIFICATION BREEDING IN LOWLAND RICE

Experimental Agriculture ◽

10.1017/s0014479717000084 ◽

2017 ◽

Vol 54 (3) ◽

pp. 382-398 ◽

Cited By ~ 1

Author(s):

F.H.C. RUBIANES ◽

B.P. MALLIKARJUNA SWAMY ◽

S.E. JOHNSON-BEEBOUT

Keyword(s):

Water Management ◽

Field Experiment ◽

Irrigation Management ◽

Grain Filling ◽

Greenhouse Experiment ◽

Zn Deficiency ◽

Zn Uptake ◽

Zn Concentration ◽

Soil Zn ◽

Grain Zn Concentration

SUMMARYAs zinc (Zn) fertilizer and water management affect the expression of Zn-enriched grain traits in rice, we studied the effect of Zn fertilizer and water management on Zn uptake and grain yield of different biofortification breeding lines and the possible biases in selection for high grain Zn content. The first field experiment showed that longer duration genotypes had higher grain Zn uptake rate than shorter duration genotypes during grain filling. In the first greenhouse experiment, neither application of Zn fertilizer at mid-tillering nor application at flowering significantly increased the grain Zn concentration. In the second greenhouse experiment, application of alternate wetting and drying (AWD) significantly increased the available soil Zn and plant Zn uptake but not grain Zn concentration. Terminal drying (TD) did not increase the available soil Zn or grain Zn contents. The second field experiment confirmed that differences in TD were not important in understanding differences between genotypes. Zn application is not always necessary to breeding trials unless there is a severe Zn deficiency and there is no need to carefully regulate TD prior to harvest.

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Good soil management can reduce dietary zinc deficiency in Zimbabwe

CABI Agriculture and Bioscience ◽

10.1186/s43170-021-00057-4 ◽

2021 ◽

Vol 2 (1) ◽

Author(s):

Muneta G. Manzeke-Kangara ◽

Edward J. M. Joy ◽

Florence Mtambanengwe ◽

Prosper Chopera ◽

Michael J. Watts ◽

...

Keyword(s):

Soil Fertility ◽

Zn Deficiency ◽

Soil Fertility Management ◽

Management Scenarios ◽

Fertility Management ◽

Zn Concentration ◽

Maize Grain ◽

Soil Zn ◽

Nutrient Resources ◽

Grain Zn Concentration

Abstract Background Dietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of surveys and field experiments. Methods An ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios. Results A baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg−1 and an estimated dietary Zn intake of 9.3 mg capita−1 day−1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and woodland leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg−1. This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2238 DALYs year−1. Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg−1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9119 DALYs year−1. Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods. Conclusion Farmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

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Soil-application of Zinc-EDTA Increases Leaf Photosynthesis of Immature ‘Wichita’ Pecan Trees

Journal of the American Society for Horticultural Science ◽

10.21273/jashs03938-16 ◽

2017 ◽

Vol 142 (1) ◽

pp. 27-35 ◽

Cited By ~ 1

Author(s):

Richard J. Heerema ◽

Dawn VanLeeuwen ◽

Marisa Y. Thompson ◽

Joshua D. Sherman ◽

Mary J. Comeau ◽

...

Keyword(s):

Gas Exchange ◽

Leaf Gas Exchange ◽

Calcareous Soils ◽

Leaf Tissue ◽

Growing Season ◽

Zn Deficiency ◽

Soil Application ◽

Zn Concentration ◽

Significant Difference ◽

Soil Zn

Zinc deficiency is common in pecan (Carya illinoinensis) grown in alkaline, calcareous soils. Zinc (Zn)-deficient pecan leaves exhibit interveinal chlorosis, decreased leaf thickness, and reduced photosynthetic capacity. Low photosynthesis (Pn) contributes to restricted vegetative growth, flowering, and fruiting of Zn-deficient pecan trees. Our objectives were to measure effects of soil-applied ethylenediaminetetraacetic acid (EDTA)-chelated Zn fertilizer on gas exchange of immature ‘Wichita’ pecan and characterize the relationship between leaf Zn concentration and Pn. The study orchard had alkaline and calcareous soils and was planted in Spring 2011. Zinc was applied throughout each growing season as Zn EDTA through microsprinklers at rates of 0 (Control), 2.2, or 4.4 kg·ha−1 Zn. Leaf gas exchange and SPAD were measured on one occasion in the 2012 growing season, four in 2013, and five in 2014. Soil Zn-EDTA applications significantly increased the leaf tissue Zn concentration throughout the study. On all measurement occasions, net Pn was significantly increased by soil-applied Zn EDTA compared with the control, but Pn was not different between the two soil-applied Zn-EDTA treatments. Leaf Pn in midseason did not increase at leaf tissue Zn concentrations above 14–22 mg·kg−1. Leaf SPAD consistently followed a similar pattern to Pn. Soil Zn-EDTA application increased leaf stomatal conductance (gS) compared with the Control early through midseason but not after August. Intercellular CO2 concentration was significantly lower for Zn-EDTA-treated trees than the Control even on dates when there was no significant difference in gs, which suggests that soil application of Zn-EDTA alleviated nonstomatal limitations to Pn caused by Zn deficiency.

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Quantify the Requirements to Achieve Grain Zn Biofortification of High-yield Wheat on Calcareous Soils

10.1101/2020.04.09.033639 ◽

2020 ◽

Author(s):

Sen Wang ◽

Zhaohui Wang ◽

Shasha Li ◽

Chaopeng Diao ◽

Lu Liu ◽

...

Keyword(s):

Harvest Index ◽

Calcareous Soils ◽

High Yield ◽

Zn Deficiency ◽

Food Crops ◽

Established Method ◽

Zn Uptake ◽

Zn Concentration ◽

Zn Distribution ◽

Grain Zn Concentration

AbstractThe solution to address global human Zn deficiency is Zn biofortification of staple food crops, aimed at high grain Zn concentration as well as high yield. However, the desired high grain Zn concentration above 40 mg kg-1 is rarely observed for high-yield wheat on worldwide calcareous soils, due to inadequate Zn uptake or Zn distribution to grain. The present study aims to investigate how much Zn uptake or distribution is adequate to achieve the Zn.t of high-yield wheat on calcareous soils with low available Zn (∼ 0.5 mg kg-1). Of the 123 cultivars tested in a three-year field experiment, 19 high-yield cultivars were identified with similar yields around 7.0 t ha-1 and various grain Zn concentrations from 9.3 to 26.7 mg kg-1. The adequate Zn distribution to grain was defined from the view of Zn biofortification, as the situation where the Zn distribution to grain (Zn harvest index) increased to the observed maximum of ∼ 91.0% and the Zn concentration of vegetative parts (straw Zn concentration) decreased to the observed minimum of ∼ 1.5 mg kg-1 (Zn.m). Under the assumed condition of adequate Zn distribution to grain (∼ 91.0%), all the extra Zn above Zn.m was remobilized from straw to grain and the grain Zn concentration would be increased to its highest attainable level, which was 14.5 ∼ 31.3 mg kg-1 for the 19 high-yield cultivars but still lower than 40 mg kg-1. Thus, even with the adequate Zn distribution to grain, the current Zn uptake is still not adequate and needs to be increased to 308 g ha-1 or higher to achieve Zn.t for high-yield wheat (7.0 t ha-1) on low-Zn calcareous soils. Besides, the established method here can also provide the priority measures and quantitative guidelines to achieve Zn biofortification in other wheat production regions.

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Good soil management can reduce dietary zinc deficiency in Zimbabwe.

10.31220/agrirxiv.2021.00033 ◽

2021 ◽

Author(s):

Muneta G. Manzeke-Kangara ◽

Edward J. M. Joy ◽

Florence Mtambanengwe ◽

Prosper Chopera ◽

Michael J. Watts ◽

...

Keyword(s):

Soil Fertility ◽

Zn Deficiency ◽

Soil Fertility Management ◽

Management Scenarios ◽

Fertility Management ◽

Zn Concentration ◽

Maize Grain ◽

Soil Zn ◽

Nutrient Resources ◽

Grain Zn Concentration

Abstract Dietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of survey and field experiments. An ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios. A baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg-1 and an estimated dietary Zn intake of 9.3 mg capita-1 day-1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg-1. This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2,238 DALYs year-1. Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg-1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9,119 DALYs year-1. Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods. Farmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

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Zinc application enhances grain zinc density in genetically-zinc-biofortified wheat grown on a low-zinc calcareous soil

Journal of Scientific Agriculture ◽

10.25081/jsa.2018.v2.20181512 ◽

2018 ◽

pp. 107-110 ◽

Cited By ~ 1

Keyword(s):

Developing Countries ◽

Grain Yield ◽

Calcareous Soil ◽

Zn Deficiency ◽

Target Level ◽

Zn Concentration ◽

Grain Zinc ◽

Zn Availability ◽

Zinc Application ◽

Grain Zn Concentration

Human zinc (Zn) deficiency is a worldwide problem, especially in developing countries due to the prevalence of cereals in the diet. Among different alleviation strategies, genetic Zn biofortification is considered a sustainable approach. However, it may depend on Zn availability from soils. We grew Zincol-16 (genetically-Zn-biofortified wheat) and Faisalabad-08 (widely grown standard wheat) in pots with (8 mg kg−1) or without Zn application. The cultivars were grown in a low-Zn calcareous soil. The grain yield of both cultivars was significantly (P≤0.05) increased with that without Zn application. As compared to Faisalabad-08, Zincol-16 had 23 and 41% more grain Zn concentration respectively at control and applied rate of Zn. Faisalabad-08 accumulated about 18% more grain Zn concentration with Zn than Zincol-16 without Zn application. A near target level of grain Zn concentration (36 mg kg−1) was achieved in Zincol-16 only with Zn fertilisation. Over all, the findings clearly signify the importance of agronomic Zn biofortification of genetically Zn-biofortified wheat grown on a low-Zn calcareous soil.

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Soil and foliar zinc application to biofortify broccoli (Brassica oleracea var. italica L.): effects on the zinc concentration and bioavailability

Plant Soil and Environment ◽

10.17221/14/2020-pse ◽

2020 ◽

Vol 66 (No. 3) ◽

pp. 113-118

Author(s):

Angelica Rivera-Martin ◽

Martin R Broadley ◽

Maria J Poblaciones

Keyword(s):

Phytic Acid ◽

Acid Concentration ◽

Zinc Concentration ◽

Zn Deficiency ◽

Mineral Concentration ◽

Zn Concentration ◽

Foliar Treatment ◽

Soil Zn ◽

Foliar Zinc Application ◽

Zinc Application

Agronomic zinc (Zn) biofortification of crops could help to alleviate dietary Zn deficiency, which is likely to affect more than one billion people worldwide. To evaluate the efficiency of agronomic Zn biofortification of broccoli, four application treatments were tested: no Zn application (control); soil application of 5 mg/kg ZnSO4·7 H2O (soil); two sprays (15 mL/pot each) of 0.25% (w/v) ZnSO4·7 H2O (foliar); and soil + foliar combination. Soil Zn application increased Zn-DTPA (diethylenetriamine pentaacetic acid) concentration by 3.7-times but did not affect plant growth or plant Zn concentration. Foliar Zn application increased stem + leaves and floret Zn concentration by 78 and 23 mg Zn/kg, respectively, with good bioavailability based on phytic acid concentration. Boiling decreased mineral concentration by 19%, but increased bioavailability by decreasing the phytic acid concentration. The entire broccoli could constitute a good nutritional source for animals and humans. An intake of 100 g boiled florets treated with the foliar treatment will cover about 36% of recommended dietary intake (RDI) of Zn, together with 30% of Ca, 94% of K, 32% of Mg, 6% of Na, 55% of P, 60% of S, 10% of Cu, 22% of Fe, 43% of Mn, and 35% of Se RDIs.

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THE MECHANISM OF PHOSPHORUS-INDUCED ZINC DEFICIENCY IN BEAN (Phaseolus vulgaris L.)

Canadian Journal of Soil Science ◽

10.4141/cjss88-032 ◽

1988 ◽

Vol 68 (2) ◽

pp. 345-358 ◽

Cited By ~ 47

Author(s):

J. P. SINGH ◽

R. E. KARAMANOS ◽

J. W. B. STEWART

Keyword(s):

Application Rate ◽

Water Soluble ◽

Zn Deficiency ◽

Soil P ◽

Bean Plants ◽

Zn Concentration ◽

P Application ◽

Soil Zn ◽

Dilution Effects ◽

Yield Responses

The nature of the P-induced Zn deficiency in bean plants was studied in a growth chamber experiment using three pedogenically different soils. Application of P (0, 40, 80 and 160 mg P kg−1 soil) resulted in significant dry matter (DM) yield increases. Maximum DM yields were attained at the 40 mg P kg−1 application rate. Application of Zn (0, 5 or 10 mg Zn kg−1 soil) without P application had no effect on DM yields of bean plants. However, Zn application in combination with P application resulted in significant DM yield responses. There was no evidence that the P-induced Zn deficiency was a result of differences in soil characteristics or influence of P on the water soluble plus exchangeable, organically bound, Mn- and Fe-oxide bound or residual Zn fractions. The Zn concentration in bean plant tops was significantly reduced due to P application and the magnitude of the reduction was greatest with the first increment of applied P (40 mg P kg−1 soil). Application of P induced Zn deficiency, at least partly, by stimulation of growth and subsequent dilution of tissue Zn concentration. Translocation of Zn from roots to tops appeared to be restricted at 80 and 160 mg applied P kg−1 soil treatments, as evidenced by the reduction of Zn uptake in non-Zn treatments. Thus, plant dilution effects and reduced translocation of Zn from roots to tops were the two mechanisms responsible for the observed P-induced Zn deficiency in this study. Key words: P × Zn interaction, plant availability, plant uptake, soil Zn fractions, soil P, Zinc-65

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Bioavailability of Zinc in Bread Wheat Grown in the Calcareous Soils of the Kurdistan Region of IRAQ

10.21203/rs.3.rs-221652/v1 ◽

2021 ◽

Author(s):

Muhammed S. Rasheed ◽

Scott Young ◽

Elezabeth Bailey

Keyword(s):

Local Population ◽

Calcareous Soils ◽

Phosphate Fertilizer ◽

Kurdistan Region ◽

Wheat Grain ◽

Whole Wheat ◽

Zn Concentration ◽

Zn Bioavailability ◽

Soil Zn ◽

Whole Grain Flour

Abstract A survey of wheat grain from 120 fields in Sulaimanyah province, Kurdistan region, Iraq was undertaken in 2017. We evaluated the concentrations of phosphorus (P), Zn and phytic acid (PA) and the estimated Zn bioavailability in wheat grain grown in the calcareous soils of the region. Concentrations of P in wheat grain were higher than the recommended value of 3570 mg kg− 1; PA was within the range of other countries but Zn concentration in 88% of wheat grain samples fell below the value recommended for human nutrition of 41.6 mg kg− 1. Bioavailable Zn intake (mg d− 1) was estimated assuming bread consumption of 300 g day− 1 in the region. Considering PA and Zn intake suggested only 21.5 ± 2.9% of whole grain flour Zn was bioavailable. Thus the effective Zn intakes from whole wheat was only 1.25–2.05 mg d− 1 for the local population. Typical dietary Zn was below recommended levels (11 mg d− 1), due to low soil Zn uptake by wheat and the large concentrations of PA in wheat grains, probably from over-use of phosphate fertilizer.

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Study of genetic diversity in different wheat species with various genomes based on morphological characteristics and zinc use efficiency under two zinc-deficient growing conditions

Acta agriculturae Slovenica ◽

10.14720/aas.2019.113.1.13 ◽

2019 ◽

Vol 113 (1) ◽

pp. 147 ◽

Cited By ~ 1

Author(s):

Majid ABDOLI ◽

Ezatollah ESFANDIARI ◽

Aliasghar ALILOO ◽

Behzad SADEGHZADEH ◽

Seyed-Bahman MOUSAVI

Keyword(s):

Dry Matter ◽

Calcareous Soils ◽

Morphological Characteristics ◽

Utilization Efficiency ◽

Zn Deficiency ◽

Wheat Genotypes ◽

Zn Efficiency ◽

Zn Concentration ◽

Zn Content ◽

Growing Conditions

Screening of cash crops to tolerate and grow under low levels of micronutrients is important issue in the plant breeding programs. Thus, the study screened the tolerance of 50 wheat genotypes to zinc (Zn) deficiency in the calcareous soil. The Zn treatment was carried out with application of 5 mg kg-1 (+Zn) and without (-Zn) to the collected soils with initial Zn extractable of 0.5 mg Zn kg-1 soil. The results revealed that the supplementary application significantly increased shoot dry matter, shoot Zn concentration and shoot Zn content compared to the without Zn application (control), but Zn utilization decreased under Zn application. There was considerable genetic variation in Zn efficiency (55 - 118 %), shoot Zn concentration (11.8 - 27.0 and 14.3 - 39.6 mg kg-1 DM under deficient and sufficient Zn, respectively), shoot Zn content (0.56 - 2.02 and 0.90 - 2.83 µg plant-1, under deficient and sufficient Zn, respectively) and Zn utilization efficiency (39 - 87.2 and 31.2 - 71.5 mg DM µg-1 Zn under deficient and sufficient Zn, respectively) within wheat genotypes. Cluster analysis based on Zn efficiency, and shoot dry matter at deficient and adequate Zn conditions classified the genotypes into four clusters. Over the two conditions, the most Zn-efficient and Zn-unefficient genotypes were ‘Ankara-98’ and ‘Altintoprak-98’ and ‘Pg"S’ and ‘Zarin’, respectively. Most durum genotypes had a greater Zn efficiency than modern bread wheat genotypes, therefore these genotypes could be effectively used to breed the new cultivars with high Zn efficiency for calcareous soils.

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