Figure 4.

Leaf application of both HMW chitosan and T. atroviride spores are beneficial for growth promotion of young B. vulgaris plants. (A–C) B. vulgaris was grown in a greenhouse from May to August 2021 without additional heating. At 37 and 57 days, the leaves of the plants were either sprayed with deionized water pH 4.5 (control), 1 mg mL⁻¹ of high-molecular-weight chitosan solution, pH 4.5 (HMW), or a freshly prepared T. atroviride 10⁴ spores mL⁻¹ solution in deionized water (TA.SP). Twenty days after the first treatment (A,B) and thirteen days after the second treatment (C), the plants were photographed and arranged according to size for better comparison. (D) At the same time as shown in (A,C), a leaf from each plant in comparable size was harvested for RNA extraction and expression analysis. The data from all six plants per condition were combined and compared to the control condition for each treatment. The data are presented in a heatmap where red indicates upregulation and blue downregulation of expression. GLU, SE2, and PR-3 indicate expression of genes related to pathogenesis; AAT and PAL are related to plant growth and cell wall strengthening; and GST and DMRL are related to the oxidative burst. See Table S3 for statistical significance. n = 6 biological replicates and 3 technical replicates.