Prospecting phosphate solubilizing bacteria in alkaline-sodic environments reveals intra-specific variability in Pantoea eucalypti affecting nutrient acquisition and rhizobial nodulation in Lotus tenuis

CUMPA-VELÁSQUEZ, LIZ MARJORY; MORICONI, JORGE IGNACIO; DIP, DIANA PATRICIA; CASTAGNO, LUIS NAZARENO; PUIG, MARÍA LUCRECIA ; MAIALE, SANTIAGO JAVIER; SANTA MARÍA, GUILLERMO ESTEBAN; SANNAZZARO, INÉS ANALÍA ; ESTRELLA, MARÍA JULIA

APPLIED SOIL ECOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021

0929-1393

A bioprospecting study inalkaline-sodic soils of the Argentinean flooding pampa was performed in orderto identify and characterize rhizospheric bacteria associated to Lotus tenuisplants, capable of solubilizing phosphate under a broad range of alkaline-sodicconditions. Our analysis, supported by repetitive BOX element based PCR and 16SrRNA sequences, identified 74 strains. All of them belong to the PhylumProteobacteria, specifically to the order Enterobacteriales, andPseudomonadales, suggesting that in this environment, broad pH-rangeP-solubilizing bacteria (BRPSB) associated to L. tenuis, are grouped within anarrow taxonomic range. A subsequent objective was to focus in a subgroup ofBRPSB strains belonging to the Pantoea eucalypti species (MA66, P63, P76, P163,P173 and a formerly identified isolate, M91) that also produced siderophores,indol-acetic acid and showed in vitro compatibility with the native rhizobialstrain Mesorhizobium sanjuanii BSA136. Growth promoting effects of these P.eucalypti strains on L. tenuis plants in alkaline-sodic soils in symbiosis withthe above mentioned rhizobial strain were analyzed. Despite all the P.eucalypti BRPSB strains exhibited the above-mentioned features, they exerteddifferential effects on plant growth and dry matter allocation to the nodules.Plants inoculated with P. eucalypti M91 displayed a superior capability toaccumulate nitrogen, phosphorus and zinc. On the contrary, nodules dry matterallocation, and mineral nutrient accumulation in L. tenuis plants werenegatively affected by P. eucalypti P76 compared with M91. Results herebypresented highlight the complexity of plant-microbe interactions and revealthat growth-promoting effects of P-solubilizing P. eucalypti strains cannot bepredicted only on the basis of their in vitro PGPR features, complementary inplanta assays being necessary for efficient strain selection. This studyprovides valuable information for biofertilization of L. tenuis plants in theflooding pampa.