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 LM; MORICONI JI; DIP DP; CASTAGNO LN; PUIG ML; MAIALE SJ; SANTA-MARÍA GE; SANNAZZARO AI; ESTRELLA MJ

APPLIED SOIL ECOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021

0929-1393

Abioprospecting study in alkaline-sodic soils of the argentinean floodplainregion was performed in order to characterize the native rhizospheric communityof the forage legume Lotus tenuiswith the ability to solubilize phosphate (P) at neutral pH and within thealkaline range in the presence of Na+. Our analysis, supported by repetitive BOX element‐based PCR and 16S rRNAsequences, identified 74 strains. All of them belong to the ProteobacteriaPhylum, specifically to the Enterobacteriaceaeand Pseudomonadaceae families, indicatingthat, in this environment, the diversity of broad pH range P-solubilizingbacteria (BRPSB) associated to L. tenuis involves a narrow taxonomicrange. A detailed characterization of a subgroup of these BRPSB, classified asmembers of the Pantoea eucalyptispecies (MA66, P63, P76, P163, P173 and a formerly identified isolate, M91)revealed that they also produce siderophores, indol-acetic acid and showed invitro compatibility with the native nitrogen-fixing bacteria Mesorhizobium sanjuanii BSA136. Despitesharing these in vitro characteristics, plants co-inoculated with thosestrains and M.sanjuanii BSA136 showed differential patterns of growth and dry matterallocation to the nodules. An examination of the accumulation of mineralnutrients indicated that P eucalyptiplants co-inoculated with M91 displayed a superior capability to accumulatenitrogen, phosphorus and zinc. On the contrary, both allocation of dry matterto nodules and mineral nutrient accumulation in L. tenuiswere negatively affected by P76 strain. Our study highlights the complexity ofplant-microorganism interactions, and particularly the level of specificity ofthe strains involved in the tripartite PSB-rhizobia-leguminous interactions.Furthermore, we suggest that taxonomic identity and in vitro attributes are tools of limited predictive value for the interactionof BRPSB strains with rhizobia-L. tenuis.