Fig. 3 | Nature Communications

Fig. 3

From: A mutualistic interaction between Streptomyces bacteria, strawberry plants and pollinating bees

Fig. 3

SP6C4 antagonism in vitro against gray mold pathogen, colonization of the flower surface and the honeybee body. a Mycelium growth inhibition of Botrytis cinerea by strain SP6C4 and SF7B6 on PDK agar. Two strains were streaked on PDK agar with toothpicks. After 3 days, the pathogen agar block (0.7-mm) was placed at the center of the plate, then the plate was incubated for 7 days at 28 °C. b Flowers (n = 3) received 100 μL of the bacterial suspension (106 cfu/mL, 0.1% methyl cellulose). The flowers were incubated in a growth chamber (16 h light, 28 °C; 8 h of dark, 24 °C). After 5 days, they were collected into 30 mL of PBS buffer and spread on PDK media with hygromycin (80 μg/mL). Bars represent standard deviation (Paired sample t-test: SF 0 day vs SF after 5 days, P = 0.002854; SP 0 days vs SP after 5 days, P = 0.003858; **P < 0.01). c Experimental illustration of SP6C4 colonization of the honeybee body and gut. d SP6C4 or SF7B6 (106 cfu/mL, 0.1% methyl cellulose) were introduced in a 5-cm Petri dish. After 5 days, bacterial population density was investigated both on the surface and in the gut of the honeybees. For honeybee surface colonization by the bacteria, the bodies were placed in 50 mL of PBS buffer and sonicated for 10 min. For gut samples, the bodies were rinsed three times with sterile water and gut tissue was extracted. The samples were diluted to 10−7, spread on PDK agar with hygromycin (80 μg/mL), the plate was incubated at 28 °C for 5 days and colony forming units were calculated. Differences in the bacterial colonization among the treatments were analyzed by independent two sample t-test (Bacterial stock: P = 0.007393, Honeybee body: P = 0.5705, Honeybee gut: P = 0.5355 and bars represent standard deviation. d Source data are provided as a Source Data file

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