Fig. 5
From: Glutamic acid reshapes the plant microbiota to protect plants against pathogens
Microbial engineering with l-glutamic acid (5 μg/ml) for control of plant disease. Strawberry plants were chilled at – 2 °C for 1 month and transplanted into plastic pots (10 cm diam.) with autoclaved soil. A Microbial engineering experiment design in the strawberry anthosphere and tomato rhizosphere. At strawberry flowering (12 days), l-glutamic acid (5 μg/ml) and antibiotics (erythromycin and clindamycin, 10 μg/ml each) were applied. Three days later, conidia of the gray mold pathogen B. cinerea (BC, 105 cfu/ml) were sprayed onto the flower surface. B Infected strawberry flowers were counted to determine disease incidence (n = 30). C Copy number of the SP6C4-specific lanM gene (grisin) on strawberry flowers was determined by qPCR (n = 5, replication). Tomato grown on autoclaved soil with 0.1% Hoagland’s solution (n = 9 independent replicates). After 12 days, plants were drenched with 50 ml of l-glutamic acid (5 μg/ml). Six hours later, antibiotics (erythromycin and clindamycin, 10 μg/ml each) were added to the soil. At 15 days, plants were inoculated with 10 ml of FOL conidia (105 cfu/ml). D Disease index was scored at 6 levels: 0, no symptoms; 1, slight yellowing of the lower leaves; 2, moderate yellowing of the entire plant; 3, wilted plant; 4, plants severely stunted or browning; 5, plants dead. e lanM gene (grisin) specific copy number in tomato rhizosphere by qPCR (n = 5, replication). Untreated control received 50 ml of 0.1% Hoagland’s solution treated flowers (sprayed) with l-glutamic acid (5 μg/ml) and antibiotics (erythromycin and clindamycin: each at 10 μg/ml). After 3 days, a stock of B. cinerea conidia (105 cfu/ml) was sprayed on the flower surface. Box-and-whisker plot with boundaries of the rectangles indicating the 25th and 75th percentages and the horizontal bars indicating the median. Strawberry gray mold disease severity and tomato Fusarium wilt disease indices were compared by a Kruskal-Wallis rank-sum test and calculated by Tukey’s HSD (*P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001)