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					   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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posted:11/23/2011
language:English
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