*4.3. In Planta Experiment and Relative Gene Expression Analysis in Tomato Leaves* 4.3.1. Substrate Preparation, Tomato Plant Growth, and Inoculation Procedure

For the *in planta* experiment, four different substrates were prepared from peat and clay soil with two levels of biosolid (absence or presence), to which two levels of inoculum were applied; without (−) or with (+) Forl, as described by Giannakis et al. [12]. Specifically, growth substrates were: (i) peat and clay soil 1:1 (*w*/*w*) (treatment C), (ii) peat and clay soil 1:1 (*w*/*w*), supplemented with biosolid 2% (*w*/*w*) (treatment B), (iii) peat and clay soil 1:1 (*w*/*w*) inoculated with Forl (treatment F), and (iv) peat and clay soil 1:1 (*w*/*w*) supplemented with biosolid 2% (*w*/*w*) and inoculated with Forl (treatment FB). Clay soil was characterized as 40% silt, 30% clay, 30% sand, 2.5% organic matter, and pH 7.9. Inoculations and plant growth conditions were as described by Giannakis et al. [12]. Specifically, Forl inoculum, prepared as described above, was mixed thoroughly into the substrates at a 1/10 volume ratio, to a final concentration of 105 spores g−<sup>1</sup> substrate. Non-inoculated substrates were mixed with water. Tomato seedlings of the cv. ACE 55 at the two-leaf stage were transplanted in the different substrates in 0.1 L pots. All plants were placed in the same growth chamber and were grown under controlled conditions at 20–25 ◦C with 14/10 h photoperiod light/dark, respectively, and 60% RH.
