PHOSPHOROUS MOVILIZATION IN STRAWBERRY PLANTS BY A STRAIN OF MESORHIZOBIUM MEDITERRANEUM WHICH NODULATES CICER ARIETINUM Alvaro Peix1, Laura Martín-Martín1, Eustoquio Martínez-Molina1, Pedro F. Mateos1, Claudino Rodríguez-Barrueco2, Encarna Velázquez1 Departamento de Microbiología y Genética. Universidad de Salamanca Phosphorous is, after nitrogen, the second most important element in plant nutrition In many plants of agronomic interest, phosphorous is a key a key factor in fruit properties and precocity, which is very important under a commercial point of view only 0.1% of the total phosphorous from soil is available to plants Among Plant Growth-Promoting Rhizobacteria, there are some strains which mode of action is based on solubilization of insoluble phosphates and mobilization of P in soil-plant interface Among Phosphate Solubilizing Bacteria, the most powerful strains are included in diverse taxonomic groups, as Gram negative Proteobacteria (pseudomonads and rhizobia) and Gram positive bacteria of low G+C content (Bacillus). Some strains of rhizobia and other related genera, besides their potential to nodulate legumes and fix atmospheric nitrogen, can solubilize phosphates and mobilize P to plants The strain PECA21 is able to nodulate, fix nitrogen and movilize phosphorous to Cicer arietinum Phosphate solubilization halos of strain PECA21 grown in YED+ 0.3% tricalcium phosphate medium Identification Stable Low Molecular Weight (LMW) RNA profiles obtained by Staircase Electrophoresis LMW RNA profiles LMW RNA profiles of type strains from Mesorhizobium nodulating Cicer arietinum and PECA21: Carril (1) M. ciceri USDA 3383T Carril (2) M. mediterraneum USDA 3392T Carril (3) PECA21 Phosphorous mobilization in strawberry plants View of fruits View of strawberry yielded by plants plants growing in from different growth chamber treatments Treatment Dry weight P (%) N(%) Production (g) (g/plant) Controls 5.83a 0.195a 1.595a 8.927a PECA21 5.46a 0.242a 1.625a 3.714a PECA21-P 5.50a 0.309b 1.670a 18.046b values followed by the same letter are not significantly different from each other at p=0.05 according to Fisher's Protected LSD Phosphorous mobilization in strawberry plants Treatment Dry P (%) N(%) Production( weight(g) g/plant) Control 5.83a 0.195a 1.595a 8.927a PECA21 5.46a 0.242a 1.625a 3.714a PECA21-P 5.50a 0.309b 1.670a 18.046b values followed by the same letter are not significantly different from each other at p=0.05 according to Fisher's Protected LSD Bar charts of parameters measured in the experiment 0,309 18,046 PECA21-P PECA21-P 1,670 5,50 0,242 %P 3,714 producción PECA21 PECA21 1,625 %N 5,46 peso seco 0,195 8,927 CONTROL CONTROL 1,595 5,83 CONCLUSIONS LMW RNA profiles obtained by Staircase electrophoresis allow the identification of phosphate solubilizing bacteria belonging to very diverse taxonomic groups. In our case strain PECA21 isolated from chickpea was identified as Mesorhizobium mediterraneum In strawberry plants inoculated with strain Mesorhizobium mediterraneum PECA21 added with phosphate, phosphorous mobilization in plant-soil interface was observed, increasing significantly their P content. Strawberry plants inoculated with strain Mesorhizobium mediterraneum PECA21 added with phosphate yielded fruit production higher than twice the quantity compared to control plants, and therefore this strains behaves as a good PGPR, showing potential as microbial inoculant for strawberry in the future.
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