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

Abstract

Soil bacteria can assist plant growth and increase uptake of nutrient elements, the question arises as to whether beneficial soil microbes confer augmented iron (Fe) content of host plants under Fe limited conditions. Herein, a novel strain of Burkholderia cepacia (strain JFW16) was isolated from rhziospheric soils of Astragalus sinicus grown under alkaline conditions. Inoculation of plants with B. cepacia JFW16 displayed increased endogenous Fe content compared with non-inoculated plants. Growth promotion and enhanced photosynthetic capacity were also observed for the inoculated plants. The inoculation with JFW16 significantly increased the rhizospheric acidification, and up-regulated the transcription of some Fe acquisition-associated genes in Astragalus sinicus. Moreover, the metabolic pathways of flavins were remarkably enhanced in the inoculated plants, showing the increased biosynthesis and release of flavins in roots. Collectively, these findings demonstrated the potential of B. cepacia JFW16 to improve Fe assimilation in agricultural crops. ARTICLE HISTORY

The Long-Term Effects of Using Phosphate-Solubilizing Bacteria and Photosynthetic Bacteria as Biofertilizers on Peanut Yield and Soil Bacteria Community

“…Inoculation with PSB or PNSB can promote plant growth and result in higher crop yields (Wu et al, 2013;Valetti et al, 2018). Burkholderia cepacia JFW16, which belongs to the genus Burkholderia and the β-proteobacteria class, has the capacity to promote growth and enhance photosynthesis in inoculated plants (Zhou et al, 2018). Moreover, in a previous study, B. tropica-inoculated plants showed a consistent increase in both the number and weight of tomato fruits when compared to uninoculated controls (Bernabeu et al, 2015).…”

Induced Systemic Resistance (ISR) and Fe Deficiency Responses in Dicot Plants

“…These microbes can directly improve Fe nutrition through the release of H + and/or Fe- solubilizing compounds to soils, like siderophores and organic acids, or by inducing changes in root physiology and architecture, which can improve the acquisition of Fe and also of other nutrients ( Orozco-Mosqueda et al, 2013 ; Jin et al, 2014 ; Mimmo et al, 2014 ; Zhao et al, 2014 ; Contreras-Cornejo et al, 2015 ; Pii et al, 2015 , 2016b ; Garnica-Vergara et al, 2016 ; Scagliola et al, 2016 ; Verbon and Liberman, 2016 ; Zhou et al, 2016a , b ; Martínez-Medina et al, 2017 ; Sonbarse et al, 2017 ; Sharifi and Ryu, 2018 ; Stringlis et al, 2018a ). In this way, it has been demonstrated that ISR-eliciting microbes can induce Fe deficiency responses in their host roots, such as enhanced ferric reductase activity, acidification of the rhizosphere, release of phenolics and flavins, and development of root hairs; and the expression of the genes associated with these responses, such as FIT , bHLH38 , bHLH39 , MYB72 , MYB10 , FRO2 , IRT1 , AHA , F6′H1 , BGLU42 , ABCG37 , and others ( Figure 1 , 2 and Table 1 ; Ribaudo et al, 2006 ; Zhang et al, 2009 ; Zamioudis et al, 2014 , 2015 ; Zhao et al, 2014 ; Pii et al, 2016b ; Scagliola et al, 2016 ; Verbon and Liberman, 2016 ; Zhou et al, 2016a , b , 2018 ; Martínez-Medina et al, 2017 ; Verbon et al, 2017 ; see also Section “Fe deficiency responses in dicot plants” and Section “Rhizosphere microbial species that induce Fe deficiency responses and improve Fe acquisition”).…”

“…Besides ET, other hormones and signaling molecules, such as auxin, GSH and NO have also been involved in both ISR and Fe deficiency responses ( Ribaudo et al, 2006 ; Graziano and Lamattina, 2007 ; Bacaicoa et al, 2009 , 2011 ; Chen et al, 2010 ; García et al, 2010 , 2011 , 2018 ; Acharya et al, 2011 ; Romera et al, 2011 , 2017 ; Jin et al, 2014 ; Contreras-Cornejo et al, 2015 ; Shanmugam et al, 2015 ; Zamioudis et al, 2015 ; Garnica-Vergara et al, 2016 ; Poupin et al, 2016 ; Zhou et al, 2016a , 2017 , 2018 ; Wang J. et al, 2017 ; Gullner et al, 2018 ; Kailasam et al, 2018 ; Sharifi and Ryu, 2018 ; Stringlis et al, 2018a ; Sumayo et al, 2018 ; Tyagi et al, 2018 ). All of them increase in roots under Fe deficiency and frequently upon colonization of roots by ISR-eliciting microbes ( Romera et al, 1999 ; Ribaudo et al, 2006 ; Graziano and Lamattina, 2007 ; Bacaicoa et al, 2009 , 2011 ; Chen et al, 2010 ; Contreras-Cornejo et al, 2015 ; Shanmugam et al, 2015 ; Zamioudis et al, 2015 ; Zhou et al, 2016a , 2017 ; Wang J. et al, 2017 ; Kailasam et al, 2018 ).…”

“…These Fe deficiency responses are induced in a similar way as they are induced under Fe deficiency conditions. For example, ISR-eliciting microbes induce the upregulation of the genes associated with the Fe deficiency responses, like FRO2 , IRT1 , AHA , F6′H1 , BGLU42 , ABCG37 , and others, and these genes are activated by the TFs that activate them under Fe deficiency, like FIT(FER), bHLH38, bHLH39, MYB72, and MYB10 ( Figure 2 ; Zhang et al, 2009 ; Palmer et al, 2013 ; Zamioudis et al, 2014 , 2015 ; Zhao et al, 2014 ; Pii et al, 2016b ; Scagliola et al, 2016 ; Verbon and Liberman, 2016 ; Zhou et al, 2016a , 2017 , 2018 ; Martínez-Medina et al, 2017 ; Verbon et al, 2017 ; Wang J. et al, 2017 ; Stringlis et al, 2018a , b ). Moreover, the hormones and signaling molecules related to the activation of these TFs, like ET, auxin, and NO, are similar in both ISR and Fe deficiency responses (see Subsection “Ethylene and other hormones and signaling molecules”).…”

Identification of Pseudomonas Spp. That Increase Ornamental Crop Quality During Abiotic Stress

“…PGPR that produce siderophores can chelate iron and make it more bioavailable to plants. Inoculation with these PGPR have been shown to increase iron content in plants (Zhou et al, 2018). The application of PGPR with the ability to enhance nutrient bioavailability have been used as a tool to reduce chemical fertilizer inputs without sacrificing crop quality (Adesemoye et al, 2009).…”