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Augmenting iron accumulation in cassava by the beneficial soil bacterium Bacillus subtilis (GBO3).

Freitas MA, Medeiros FH, Carvalho SP, Guilherme LR, Teixeira WD, Zhang H, Paré PW - Front Plant Sci (2015)

Bottom Line: Cassava (Manihot esculenta), a major staple food in the developing world, provides a basic carbohydrate diet for over half a billion people living in the tropics.Biochemical analyses reveal that shoot-propagated cassava with GB03-inoculation exhibit elevated iron accumulation after 140 days of plant growth as determined by X-ray microanalysis and total foliar iron analysis.Growth promotion and increased photosynthetic efficiency were also observed for greenhouse-grown plants with GB03-exposure.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, Agriculture and Soil Science, Federal University of Lavras Lavras, Brazil.

ABSTRACT
Cassava (Manihot esculenta), a major staple food in the developing world, provides a basic carbohydrate diet for over half a billion people living in the tropics. Despite the iron abundance in most soils, cassava provides insufficient iron for humans as the edible roots contain 3-12 times less iron than other traditional food crops such as wheat, maize, and rice. With the recent identification that the beneficial soil bacterium Bacillus subtilis (strain GB03) activates iron acquisition machinery to increase metal ion assimilation in Arabidopsis, the question arises as to whether this plant-growth promoting rhizobacterium also augments iron assimilation to increase endogenous iron levels in cassava. Biochemical analyses reveal that shoot-propagated cassava with GB03-inoculation exhibit elevated iron accumulation after 140 days of plant growth as determined by X-ray microanalysis and total foliar iron analysis. Growth promotion and increased photosynthetic efficiency were also observed for greenhouse-grown plants with GB03-exposure. These results demonstrate the potential of microbes to increase iron accumulation in an important agricultural crop and is consistent with idea that microbial signaling can regulate plant photosynthesis.

No MeSH data available.


Related in: MedlinePlus

Scanning electromicrography X-ray analysis of (I) the abaxial (A,C) and adaxial (B,D) leaf sides of cassava (M. esculenta) bacterized with B. subtilis GBO3 (A,B) or water (C,D). Red colored dots represent the presence and abundance of iron in the leaves; (II) Contents of iron (Fe), potassium (K), and calcium (Ca) in the adaxial and abaxial side of cassava (M. esculenta) determined by the Espirit 1.9 software from the X-ray generated images.
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Figure 2: Scanning electromicrography X-ray analysis of (I) the abaxial (A,C) and adaxial (B,D) leaf sides of cassava (M. esculenta) bacterized with B. subtilis GBO3 (A,B) or water (C,D). Red colored dots represent the presence and abundance of iron in the leaves; (II) Contents of iron (Fe), potassium (K), and calcium (Ca) in the adaxial and abaxial side of cassava (M. esculenta) determined by the Espirit 1.9 software from the X-ray generated images.

Mentions: In addition to GB03-induced plant-growth promotion, cassava plants were chemically analyzed for increases in iron accumulation as has been previously reported with Arabidopsis (Zhang et al., 2009). Spectrophotometric analysis of iron in the aerial portions of the plant showed almost a 400% increase in iron abundance with GB03 treatment than water controls (p = 0.0004). Since photosynthetic machinery can be unequally distributed in leaves with respect to the abaxial and adaxial surface (Fernández et al., 2008), scanning electromicrograph X-ray analysis was performed to detect nutrient abundance in highly localized foliar regions. Qualitative analysis of such foliar images, regardless of the considered treatment, indicated greater iron accumulated on the adaxial versus abaxial leaf surface, in an apparently random distribution throughout the leaf surface, not in concentrated leaf regions such as the spongy cells in the vicinity of veins, as previously reported for Cornus stolonifera (Lambert et al., 2006). Interestingly with GBO3 exposure, leaf-side differences in iron abundance increased, with an eightfold greater adaxial iron levels and no significant iron change on the abaxial side for GB03-treated plants (Figure 2). Foliar microanalysis for other nutrients did not exhibit GB03 inducibility, except for potassium in which a 17% increase with GB03 treatment was observed on abaxial leaves (Figure 2).


Augmenting iron accumulation in cassava by the beneficial soil bacterium Bacillus subtilis (GBO3).

Freitas MA, Medeiros FH, Carvalho SP, Guilherme LR, Teixeira WD, Zhang H, Paré PW - Front Plant Sci (2015)

Scanning electromicrography X-ray analysis of (I) the abaxial (A,C) and adaxial (B,D) leaf sides of cassava (M. esculenta) bacterized with B. subtilis GBO3 (A,B) or water (C,D). Red colored dots represent the presence and abundance of iron in the leaves; (II) Contents of iron (Fe), potassium (K), and calcium (Ca) in the adaxial and abaxial side of cassava (M. esculenta) determined by the Espirit 1.9 software from the X-ray generated images.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4524923&req=5

Figure 2: Scanning electromicrography X-ray analysis of (I) the abaxial (A,C) and adaxial (B,D) leaf sides of cassava (M. esculenta) bacterized with B. subtilis GBO3 (A,B) or water (C,D). Red colored dots represent the presence and abundance of iron in the leaves; (II) Contents of iron (Fe), potassium (K), and calcium (Ca) in the adaxial and abaxial side of cassava (M. esculenta) determined by the Espirit 1.9 software from the X-ray generated images.
Mentions: In addition to GB03-induced plant-growth promotion, cassava plants were chemically analyzed for increases in iron accumulation as has been previously reported with Arabidopsis (Zhang et al., 2009). Spectrophotometric analysis of iron in the aerial portions of the plant showed almost a 400% increase in iron abundance with GB03 treatment than water controls (p = 0.0004). Since photosynthetic machinery can be unequally distributed in leaves with respect to the abaxial and adaxial surface (Fernández et al., 2008), scanning electromicrograph X-ray analysis was performed to detect nutrient abundance in highly localized foliar regions. Qualitative analysis of such foliar images, regardless of the considered treatment, indicated greater iron accumulated on the adaxial versus abaxial leaf surface, in an apparently random distribution throughout the leaf surface, not in concentrated leaf regions such as the spongy cells in the vicinity of veins, as previously reported for Cornus stolonifera (Lambert et al., 2006). Interestingly with GBO3 exposure, leaf-side differences in iron abundance increased, with an eightfold greater adaxial iron levels and no significant iron change on the abaxial side for GB03-treated plants (Figure 2). Foliar microanalysis for other nutrients did not exhibit GB03 inducibility, except for potassium in which a 17% increase with GB03 treatment was observed on abaxial leaves (Figure 2).

Bottom Line: Cassava (Manihot esculenta), a major staple food in the developing world, provides a basic carbohydrate diet for over half a billion people living in the tropics.Biochemical analyses reveal that shoot-propagated cassava with GB03-inoculation exhibit elevated iron accumulation after 140 days of plant growth as determined by X-ray microanalysis and total foliar iron analysis.Growth promotion and increased photosynthetic efficiency were also observed for greenhouse-grown plants with GB03-exposure.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Pathology, Agriculture and Soil Science, Federal University of Lavras Lavras, Brazil.

ABSTRACT
Cassava (Manihot esculenta), a major staple food in the developing world, provides a basic carbohydrate diet for over half a billion people living in the tropics. Despite the iron abundance in most soils, cassava provides insufficient iron for humans as the edible roots contain 3-12 times less iron than other traditional food crops such as wheat, maize, and rice. With the recent identification that the beneficial soil bacterium Bacillus subtilis (strain GB03) activates iron acquisition machinery to increase metal ion assimilation in Arabidopsis, the question arises as to whether this plant-growth promoting rhizobacterium also augments iron assimilation to increase endogenous iron levels in cassava. Biochemical analyses reveal that shoot-propagated cassava with GB03-inoculation exhibit elevated iron accumulation after 140 days of plant growth as determined by X-ray microanalysis and total foliar iron analysis. Growth promotion and increased photosynthetic efficiency were also observed for greenhouse-grown plants with GB03-exposure. These results demonstrate the potential of microbes to increase iron accumulation in an important agricultural crop and is consistent with idea that microbial signaling can regulate plant photosynthesis.

No MeSH data available.


Related in: MedlinePlus