Beauveria bassiana: An entomopathogenic fungus alleviates Fe chlorosis symptoms in plants grown on calcareous substrates

- Beauveria bassiana colonized vegetal tissues of tomato and wheat after seed inoculation.
- For first time B. bassiana (entomopathogenic fungus) is used to improve Fe nutrition.
- No direct negative effect of B. bassiana on plant growth have been detected.
- B. bassiana altered mineral nutrition (K).

Entomopathogenic fungi are known due to their ability to kill insects and besides they can play other roles, such as promoting plant growth or improving nutrient uptake. The main aim of this work was to assess the potential of Beauveria bassiana strain EABb 04/01-Tip for improving iron (Fe) nutrition in plants grown on calcareous substrates. Plants of a dicot (tomato) and a monocot (wheat) were pot-grown on an artificial substrate consisting of 0-240 g kg−1 Fe oxide-coated sand (FOCS), 250 g kg−1 calcium carbonate sand and quartz sand. The plants were subjected to two different treatments, namely seed dressing, which involved inoculating seeds with a conidial suspension of B. bassiana before sowing, and a control without inoculation. Leaf chlorophyll concentrations (SPAD) and Fe uptake by plants were correlated with the FOCS content of the substrate, therefore the experimental design was appropriate to see different levels of Fe chlorosis symptoms. B. bassiana was able to colonise both tomato and wheat plants without a negative effect on plant height, plant dry weight, root development in tomato or grain production in wheat. In addition, B. bassiana alleviated Fe chlorosis symptoms (described for first time) in both crops during early growing stages (<50 days after sowing) but the intensity of the effect depended on the plant species and available Fe on substrate. Nutritional alterations in K due to fungal application were detected in tomato and wheat plants.