Fig 4.

Treatment with S. meliloti strain producing oxo-C14-HSL increases resistance against late blight in tomato. Roots of tomato cv. Moneymaker plants were inoculated via watering with the oxo-C14-HSL-producing S. meliloti strain expR+, the attM lactonase-expressing S. meliloti attM strain or MgSO₄ (control) for 4 weeks prior to inoculation with the oomycete Phytophthora infestans. Disease symptoms were assessed 1 week after inoculation. Data represent mean from three independent repetitions.A. Efficiency of treatment assessed using the Abbott formula. *P ≤ 0.05 in ANOVA.B. Macroscopic symptoms caused by the late blight agent P. infestans on tomato plants.