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

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.

Plant defense approach ofBacillus subtilis(BERA 71) againstMacrophomina phaseolina(Tassi) Goid in mung bean

“…The 16S rDNA sequence of B. subtilis BERA 71 was submitted to the Gen Bank nucleotide sequence database and the accession number was given as KX090253. The formulation of B. subtilis was done by following the method of Hashem et al (2013) (Freitas et al 2015) were inoculated with 10 6 CFU (colony forming unit)/mL (1.0 mL/flask) and incubated at 25 ± 1°C for 48 h under continuous shaking at 150 rpm. After incubation, the bacterial samples were lyophilized under vacuum and the lyophilized powder was mixed with talc powder and 1.0% carboxy methyl cellulose (w/w) as an adhesive agent to give a final concentration of 3.6 × 10 9 CFU of B. subtilis/g of formulated material (Hashem et al 2013).…”

Bacillus spp. inoculation improves photosystem II efficiency and enhances photosynthesis in pepper plants

“…Inoculation with B. subtilis increase photosynthesis in Arabidopsis through the modulation of plant endogenous sugar/abscisic acid (ABA) signaling, with a regulatory role for plant symbionts in photosynthesis (Zhang et al, 2008). However, Freitas et al (2015) showed that iron accumulation in cassava was accompanied by an increase in the photosynthetic rate and biomass accumulation and may be linked with greater chlorophyll levels at this location. In this way, B. subtilis has been shown to increase the abundance of transcripts involved in iron uptake and transport as well as induce rhizosphere acidification that directly mobilizes soluble minerals (Zhang et al, 2009).…”

Improved iron acquisition ofAstragalus sinicusunder low iron-availability conditions by soil-borne bacteriaBurkholderia cepacia

“…Importantly, some PGPR strains have great potential to improve Fe absorption in plants (Pii et al 2015(Pii et al , 2016Zhou et al 2016). Bacillus subtilis GB03 activates the Fe acquisition machinery in Arabidopsis and cassava (Manihot esculenta) plants (Zhang et al 2009;Freitas et al 2015). Zhou et al (2016) have reported that the inoculation with Paenibacillus polymyxa BFKC01 increases Fe content in Arabidopsis plants under alkaline conditions.…”