The Fungal Endophyte Does Not Affect Phosphorus Status but Carbon and Nitrogen Dynamics in Arbuscular Mycorrhizal Tomato Plants.

Some members of the root endophytic Serendipitaceae were observed to frequently coexist with arbuscular mycorrhizal fungi (AMF), but their interactions and potential synergistic effects in plants have not yet been well elucidated. Here, we inoculated three-week-old tomato seedlings with or alone or in combination with the arbuscular mycorrhizal fungus and cultivated the plants in a greenhouse until the late vegetative stage. Our data show that the simultaneous presence of spp. did not affect root colonization by AMF, proving the feasibility of their combination for future agronomic uses. The photosynthetic performance was enhanced in AM tomato plants, although growth remained unresponsive following single or dual inoculation with spp. and AMF. With regard to nutrient status under dual inoculation, AMF-induced phosphorus increases remained unaffected, but nitrogen and carbon dynamics were highly altered. Specifically, the application of to mycorrhizal tomato plants significantly enhanced nitrogen concentration in the shoots, but this effect was also compensated with a carbon cost. Our findings indicate that S. williamsii performs differently from S. indica when co-inoculated with AMF, and this suggests an unknown mechanism that needs more detailed investigation.