Figure 1.
Antagonism observed in dual culture of P. variabile with different strains of phytopathogens.
Colonies diameters of different phytopathogens strains were measured at day fourteen in absence (gray) or in presence (white) of the endophyte P. variabile. Error bars indicate standard deviation (n = 3). Asterisks indicate a statistically significant decrease of the growth of the phytopathogen in the presence of the endophyte by t-test (***p<0.001).
Figure 2.
Antagonism between the endophytic fungus and the phytopathogen F. oxysporum in dual culture.
P. variabile (PV) and F.oxysporum (FO). The two strains were placed at 25 mm of two opposite extremities of a Petri Dish on PDA medium and were observed at day fourteen. Disorganization of the phytopathogen’s mycelium structure can be observed. Arrow represents a pigmented line which could correspond to the biosynthesis of diffusible endophytic metabolites.
Figure 3.
Observation by optic microscopy of the mycelium of F. oxysporum in dual culture or single culture.
(A) F. oxysporum hyphae from dual culture with the endophyte. (B) F. oxysporum hyphae control. (PV) P. variabile and (FO) F.oxysporum. Optic micrographs of the mycelium of F. oxysporum from dual culture or single on agar plate with the endophyte P. variabile (14 days, 27°C). Arrows show disorganization of the hyphae in the presence of the endophyte.
Figure 4.
Transmission electron micrographs of the hyphae of F. oxysporum from dual or single culture.
(A) F. oxysporum mycelium from dual culture with the endophyte. (B) F. oxysporum mycelium control. Transmission electron micrographs of the mycelium of F. oxysporum from dual or single culture on agar plate with the endophyte P. variabile (14 days, 27°C) and showing cell death in the presence of the endophyte. N: nucleus. W: wall. S: septum. C: cellular fragments. V: vesicule.
Figure 5.
Structures of 1–6 isolated from P. variabile.
All structures were assigned by detailed analysis (NMR spectroscopic and mass data).
Table 1.
Metabolites induced by P. variabile during the competition with the phytopathogen F. oxysporum.
Table 2.
Fragmentations of the positive ion (m/z = 295.22) identified as 13-oxo-9,11-octadecadienoic acid and of the commercial standard.
Figure 6.
Compounds implied in the chemical communication between the endophyte P. variabile and the phytopathogen F. oxysporum.