Table 1.
Test fungi, oomycetes and bacteria.
Fig 1.
Dual-culture assay for bioactivity of volatile organic compounds produced by Ceratocystis fimbriata.
(a) Experimental design used with the following test organisms. Plate with C. fimbriata was on the bottom and test pathogen culture was on the top plate with the culture facing down. (b) CK: Monilinia fructicola growing on a PDA plate for 6 days. T: M. fructicola growing on a PDA plate with 6-day exposure to the VOCs from C. fimbriata. (c) CK: M. fructicola growing on a PDA plate for 4 days. R: M. fructicola after 6-day exposure to the VOCs from C. fimbriata transferred to a fresh PDA plate and grown for another 4 days. (d) M. fructicola, exposed to 0, 1, 3, 5 and 7-day old cultures of C. fimbriata for 5 days, respectively. (e) CK: Penicillium digitatum growing on a PDA plate for 6 days. T: P. digitatum growing on a PDA plate with 6-day exposure to the VOCs from C. fimbriata. (f) CK: P. digitatum growing on a PDA plate for 4 days. R: P. digitatum after 6-day exposure to the VOCs from C. fimbriata transferred to a fresh PDA plate and grown for another 4 days. (g) CK: P. italicum growing on a PDA plate for 5 days. T: P. italicum growing on a PDA plate with 5-day exposure to the VOCs from C. fimbriata. (h) CK: Phytophthora capsici growing on a CA plate for 6 days. T: P. capsici growing on a CA plate with 6-day exposure to the VOCs from C. fimbriata. (i) CK: Acidovorax avena growing on a LB plate for 2 days. T: A. avena growing on a LB plate with 2-day exposure to the VOCs from C. fimbriata.
Fig 2.
Control of citrus green mold by the VOCs from Ceratocystis fimbriata (4 DPI).
(a-b) Experimental design for the bio-control system. (c) Citrus inoculated with 10 μL conidial suspension of Penicillium digitatum at 105 conidia/mL without treatment. (d) Citrus inoculated with 10 μL conidial suspension of P. digitatum at 105 conidia/mL and treated by the VOCs from C. fimbriata. (e) Comparison among the positive control (CK+), negative control (CK-) and treated by C. fimbriata volatiles (T). (f) Pathogenicity test of the treated and recovered P. digitatum. T (treated) = the citrus inoculated with 10 μL conidial suspension of P. digitatum at 105 conidia/mL with the treatment by the VOCs form C. fimbriata. CK+ (positive control) = the citrus inoculated with 10 μL conidial suspension of P. digitatum at 105 conidia/mL without treatment. CK- (negative control) = the citrus inoculated with 10 μL sterile water without treatment. IT = inoculation with treated 2 mm plug of P. digitatum. IR = inoculation with recovered 2 mm plug of P. digitatum.
Table 2.
Effect of exposure to Ceratocystis fimbriata volatiles on the viability, mycelial growth, conidial production and spore germination of various plant pathogens.
Table 3.
Mycelial growth, conidial production and spore germination of the recovered pathogens growing on a fresh plate transferred from treated cultures.
Fig 3.
Effect of the treatment by the VOCs from Ceratocystis fimbriata applied immediately, 1 or 2 days after inoculation on the lesion size (mm2) and control effect (%) of peach brown rot and citrus green mold for four days.
Error bars represent the standard deviation of ten replicates.
Fig 4.
Lesion size (mm2) and control effect (%) of peach brown rot and citrus green mold treated by 0, 3, 5, 7, and 9 plates of Ceratocystis fimbriata culture 4 days post inoculation (DPI).
Error bars represent the standard deviation of ten replicates.
Fig 5.
Control effect (%) on peach brown rot and citrus green mold 0, 24, 48, 72, and 96 hours post inoculation (HPI) treated by ten plates of Ceratocystis fimbriata cultures.
Error bars represent the standard deviation of ten replicates.
Fig 6.
Hyphal and conidial morphology of Monilinia fructicola treated by the VOCs from Ceratocystis fimbriata observed by scanning electron microscope (SEM).
(a) Mycelia of M. fructicola growing on PDA medium. (b-e) Misshapen mycelia of M. fructicola with 6-day exposure to the VOCs from C. fimbriata. (f-i) Recovered mycelia of M. fructicola was transferred to a fresh PDA plate after 6-day exposure to the VOCs from C. fimbriata and grown for another four days. (j) Conidia of M. fructicola. (k) Misshapen conidium of M. fructicola with 6-day exposure to the VOCs from C. fimbriata. (l) Recovered conidia of M. fructicola transferred to a fresh PDA plate after 6-day exposure to the VOCs from C. fimbriata and grown for another four days.
Table 4.
Effect of the exposure to Ceratocystis fimbriata on the morphology of Monilinia fructicola and Penicillium digitatum observed by SEM.