MINERAL PHOSPHATE SOLUBILIZATION AND MOLECULAR DIVERSITY OF AZOSPIRILLUM
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Date
2007-01-02
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University of Agricultural Sciences GKVK, Banglore
Abstract
The aim of the present study was to isolate Azospirillum from different
crops and assess their molecular diversity, screen these isolates for their
activity and mobilize pqq containing construct into MPS negative
isolates and study the expression in these native Azospirillum isolates.
Thirty isolates were isolated from different crops. This work reports
about the presence of Azospirillum even in medicinal plants endorhizosphere
e.g., ashwagandha, stevia, and Vitex nigundo. The ability of the isolates to fix
atmospheric nitrogen ranged from 10.12 to 19.22 mg N per g of malate. All
the isolates produced lAA, expect five all produced GA.
Among the 30 isolates screened, 12 were found to be MPS negative but
complemented for MPS activity with PQQ supplementation, indicating that
they lacked genes for PQQ synthesis. Among these A75 and A10 isolates
showed MPS activity when PQQ was added into MSM and these were AmpR
and Tef^. Hence, a construct pJSKlS containing Pqq synthase gene(s) with
AmpR and Kan^ as.marker was mobilized into Azospirillum A75 and AlO. The
resultant transconjugants showed slight solubilization on MSM medium
than their respective wild types, indicating that the PQQ gene (s) in
pMCG898 was not sufficient to complement MPS activity in Azospirillum
isolates A75 and AlO. However, the transconjugants showed a significantly
higher Pi release of 24 and 111 per cent Pi release respectively than their
respective wild types in TCP broth.
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