Understanding the strategies to overcome phosphorus-deficiency and aluminum toxicity by ryegrass endophytic and rhizosphere phosphobacteria

dc.contributor.authorBarra, Patricio
dc.contributor.authorViscardi, Sharon
dc.contributor.authorJorquera, Milko
dc.contributor.authorDuran, Paola
dc.contributor.authorValentine, Alexander
dc.contributor.authorDe la Luz Mora, María
dc.description.abstractPhosphobacteria, secreting organic acids and phosphatases, usually favor plant performance in acidic soils by increasing phosphorus (P) availability and aluminum (Al) complexing. However, it is not well-known how P-deficiency and Al-toxicity affect the phosphobacteria physiology. Since P and Al problems often co-occur in acidic soils, we have therefore proposed the evaluation of the single and combined effects of P-deficiency and Al-toxicity on growth, organic acids secretion, malate dehydrogenase (mdh) gene expression, and phosphatase activity of five Al-tolerant phosphobacteria previously isolated from ryegrass. These phosphobacteria were identified as Klebsiella sp. RC3, Stenotrophomona sp. RC5, Klebsiella sp. RCJ4, Serratia sp. RCJ6, and Enterobacter sp. RJAL6. The strains were cultivated in mineral media modified to obtain (i) high P in absence of Al-toxicity, (ii) high P in presence of Al-toxicity, (iii) low P in absence of Al-toxicity, and (iv) low P in presence of Al-toxicity. High and low P were obtained by adding KH2PO4 at final concentration of 1.4 and 0.05 mM, respectively. To avoid Al precipitation, AlCl3 × 6H2O was previously complexed to citric acid (sole carbon source) in concentrations of 10 mM. The secreted organic acids were identified and quantified by HPLC, relative mdh gene expression was determined by qRT-PCR and phosphatase activity was colorimetrically determined using p-nitrophenyl phosphate as substrate. Our results revealed that although a higher secretion of all organic acids was achieved under P-deficiency, the patterns of organic acids secretion were variable and dependent on treatment and strain. The organic acid secretion is exacerbated when Al was added into media, particularly in the form of malic and citric acid. The mdh gene expression was significantly up-regulated by the strains RC3, RC5, and RCJ6 under P-deficiency and Al-toxicity. In general, Al-tolerant phosphobacteria under P deficiency increased both acid and alkaline phosphatase activity with respect to the control, which was deepened when Al was present. The knowledge of this bacterial behavior in vitro is important to understand and predict the behavior of phosphobacteria in vivo. This knowledge is essential to generate smart and efficient biofertilizers, based in Al-tolerant phosphobacteria which could be expansively used in acidic soilsen_US
dc.identifier.citationFrontiers in Microbiology, Vol.9, N°1en_US
dc.rightsObra bajo licencia Creative Commons 3.0en_US
dc.sourceFrontiers in Microbiology, Vol.9, N°1en_US
dc.subjectÁcido de los Suelosen_US
dc.subjectToxicidad de Aluminioen_US
dc.subjectMalato Deshidrogenasaen_US
dc.subjectDeficiencia de Fósforo-Suelosen_US
dc.subjectÁcidos Orgánicosen_US
dc.titleUnderstanding the strategies to overcome phosphorus-deficiency and aluminum toxicity by ryegrass endophytic and rhizosphere phosphobacteriaen_US
dc.typeArtículo de Revistaen_US
uct.comunidadRecursos Naturalesen_US
uct.disciplinaAgricultura y Ciencias Biológicas (General)en_US
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