*2.5. Analysis of Promoter E*ff*ects of P. variotii on Pepper and Tomato Seedlings: Experiment 1*

This experiment was performed in nursery polystyrene planting trays, each with 96 cells (70 mL volume), at a commercial nursery (Almería Province, Spain). Pepper and tomato seeds red cherry and Largo de Reus, respectively, were sown into commercial peat mix and covered with vermiculite. After 2 d (tomato) and 4 d (pepper) in a germination room (relative humidity (RH) = 95%; 25 ◦C), trays were located in a greenhouse and rinsed with water (control) or a 5 mL spore suspension per cell at 10<sup>5</sup> spores per plant. Seedlings were grown using standard nursery culture conditions (18–28 ◦C; 75.4% ± 6.7% RH) and four trays were used for each treatment. At 45 d after sowing, 20 plants per treatment and control were randomly selected from the four replications and measured for different growth parameters: number of leaves, stem length, stem base diameter, total leaf area and aerial and root dry weights. Leaf area was measured using the WINDIAS 3.1. (Delta-T Devices Ltd., Cambridge, UK, 2009) leaf area processing software. The Dickson quality index [45] was determined using the formula Dickson quality index (DQI) = TDW/((LS/D) + SDW/RDW)), where TDW is the total dry weight (g), LS is the stem length (cm), D is the stem diameter (mm) and SDW and RDM are the stem and root dry weight (g), respectively. The experiments were conducted in autumn using a completely randomized design.

#### *2.6. Analysis of E*ff*ects of Applying Di*ff*erent Doses of P. variotii to Tomatoes: Experiment 2*

For this experiment, the procedure described in experiment 1 was followed. Three doses of *P. variotii* conidia (PaeD1: 10<sup>4</sup> spores mL<sup>−</sup>1, PaeD2: 105 spores mL−<sup>1</sup> and PaeD3: 10<sup>6</sup> spores mL<sup>−</sup>1) were applied to tomato seedlings growing under commercial plant nursery conditions with irrigation of the substrate, by adding 5 mL of spore suspension to each plant. The test was conducted in winter and four replicates were performed with 96 plants per replicate. The seedlings were harvested 30 d after sowing. Twenty plants per treatment and control were randomly selected from the four replicates and measured for the same parameters as described above. Another 25 plants from each treatment were transplanted into sandy soil in mid-February and analyzed in mid-May. The experiment was

performed under greenhouse conditions (Figure 2). Water requirements were established according to climatic conditions and crop needs. Plants were fertilized with a commercial complex nutrient fertilizer.

**Figure 2.** Tomato plants grown under commercial seedlings (**A**) and field assay, 30 (**B**) and 60 (**C**) days after transplanting.

In all tests (experiments 1 and 2), tomato and pepper roots inoculated with *P. variotii* were collected at the end of the tests. Roots were surface-sterilized in 0.1% sodium hypochlorite and washed with sterilized water. Lastly, 2 cm root fragments were placed in PDA medium to determine root colonization by the fungal isolate.
