Bacillus subtilis M4 decreases plant susceptibility towards fungal pathogens by increasing host resistance associated with differential gene expression.
Results presented in this paper describe the ability of Bacillus subtilis strain M4 to reduce disease incidence caused by Colletotrichum lagenarium and Pythium aphanidermatum on cucumber and tomato, respectively. Disease protection in both pathosystems was most probably due to induction of resistance in the host plant since experiments were designed in order to avoid any direct contact between the biocontrol agent and the pathogen. Pre-inoculation with strain M4 thus sensitised both plants to react more efficiently to subsequent pathogen infection. In cucumber, the use of endospores provided a disease control level similar to that obtained with vegetative cells. In contrast, a mixture of lipopeptides from the surfactin, iturin and fengycin families showed no resistance-inducing potential. Interestingly, treatment with strain M4 was also associated with significant changes in gene transcription in the host plant as revealed by cDNA-AFLP analyses. Several AFLP fragments corresponded to genes not expressed in control plants and specifically induced by the Bacillus treatment. In support to the macroscopic protective effect, this differential accumulation of mRNA also illustrates the plant reaction following perception of strain M4, and constitutes one of the very first examples of defence-associated modifications at the transcriptional level elicited by a non-pathogenic bacterium in a host plant.
Ongena
Marc
M
Centre Wallon de Biologie Industrielle, Faculté Universitaire des Sciences Agronomiques de Gembloux, Université de Liège, Bâtiment B40, Boulevard du Rectorat 29, 4000 Liege, Belgium. ongena.m@fsagx.ac.be
Duby
Francéline
F
Jourdan
Emmanuel
E
Beaudry
Thierry
T
Jadin
Victor
V
Dommes
Jacques
J
Thonart
Philippe
P
D001412:Bacillus subtilis / Q000502:physiology*; D015152:Blotting, Northern; D020231:Colletotrichum / Q000472:pathogenicity*; D018553:Cucumis sativus / Q000382:microbiology; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000382:microbiology; D021141:Nucleic Acid Amplification Techniques; D010572:Pest Control, Biological; D010935:Plant Diseases / Q000382:microbiology*; D010944:Plants / Q000235:genetics / Q000382:microbiology*; D011775:Pythium / Q000472:pathogenicity*; D012333:RNA, Messenger / Q000032:analysis
D012333:RNA, Messenger