The type III secretion system is necessary for the development of a pathogenic and endophytic interaction between Herbaspirillum rubrisubalbicans and Poaceae.
BACKGROUND
Herbaspirillum rubrisubalbicans was first identified as a bacterial plant pathogen, causing the mottled stripe disease in sugarcane. H. rubrisubalbicans can also associate with various plants of economic interest in a non pathogenic manner.


RESULTS
A 21 kb DNA region of the H. rubrisubalbicans genome contains a cluster of 26 hrp/hrc genes encoding for the type three secretion system (T3SS) proteins. To investigate the contribution of T3SS to the plant-bacterial interaction process we generated mutant strains of H. rubrisubalbicans M1 carrying a Tn5 insertion in both the hrcN and hrpE genes. H. rubrisulbalbicans hrpE and hrcN mutant strains of the T3SS system failed to cause the mottled stripe disease in the sugarcane susceptible variety B-4362. These mutant strains also did not produce lesions on Vigna unguiculata leaves. Oryza sativa and Zea mays colonization experiments showed that mutations in hrpE and hrcN genes reduced the capacity of H. rubrisulbalbicans to colonize these plants, suggesting that hrpE and hrcN genes are involved in the endophytic colonization.


CONCLUSIONS
Our results indicate that the T3SS of H. rubrisubalbicans is necessary for the development of the mottled stripe disease and endophytic colonization of rice.
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, Brazil.
Maria Augusta
MA
Schmidt
Eduardo
E
Balsanelli
Hellison
H
Faoro
Leonardo M
LM
Cruz
Roseli
R
Wassem
Valter A
VA
de Baura
Vinícius
V
Weiss
Marshall G
MG
Yates
Humberto M F
HM
Madeira
Lilian
L
Pereira-Ferrari
Maria H P
MH
Fungaro
Francine M
FM
de Paula
Luiz F P
LF
Pereira
Luiz G E
LG
Vieira
Fábio L
FL
Olivares
Fábio O
FO
Pedrosa
Emanuel M
EM
de Souza
Rose A
RA
Monteiro
D058947:Bacterial Secretion Systems / Q000235:genetics*; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D060026:Endophytes / Q000235:genetics / Q000472:pathogenicity*; D017353:Gene Deletion; D042803:Herbaspirillum / Q000235:genetics / Q000472:pathogenicity*; D054884:Host-Pathogen Interactions; D026901:Membrane Transport Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D010935:Plant Diseases / Q000382:microbiology*; D006109:Poaceae / Q000382:microbiology*; D017422:Sequence Analysis, DNA; D037521:Virulence Factors / Q000235:genetics
D058947:Bacterial Secretion Systems; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D026901:Membrane Transport Proteins; D037521:Virulence Factors