Phosphorus-solubilizing bacteria isolated from the rhizosphere of wild potato Solanum bulbocastanum enhance growth of modern potato varieties

Abstract

Wild potato species harbor a distinctive rhizosphere microbiome relative to their modern counterparts, thus providing a competitive advantage for acquiring phosphorus (P) in their native habitats. Despite this, the effects of transferring  phosphorus-solubilizing bacteria (PSB), recruited from wild potatoes rhizosphere, on modern potato varieties’ performance has not been investigated. Here, it was hypothesized that PSB isolated from wild potatoes could enhance plant growth and solubilization of various P forms when co-inoculated with commercial potatoes (Solanum tuberosum). To test this hypothesis, three bacteria Enterobacter cloacae, Bacillus thuringiensis, and Pseudomonas pseudoalcaligenes were isolated from the rhizosphere of the wild potato Solanum bulbocastanum grown under greenhouse conditions and characterized for their P-solubilizing activities. It was found that both individual bacterial species and the consortium of the three bacteria, dissolved organic (i.e., phytin) and inorganic P (i.e., calcium phosphate) in vitro. The bacterial consortium increased dissolved P by 36-fold for calcium phosphate and sixfold for phytin compared to a sterile control and surpassed the effect of each individual PSB strain. To further evaluate the effect of the PSB consortium on plant growth and P use efficiency, the bacteria were co-inoculated on a commercial potato cultivar and amended separately with phytin, calcium phosphate, commercial P fertilizer, or a combination of the three P sources. The results showed an overall increase in total dry biomass and shoot P content in treatments co-inoculated with PSB. Our findings indicate that PSB isolated from wild potatoes and inoculated with modern potato varieties have the potential to enhance yield and nutrient uptake.