INVESTIGADORES
OTTADO Jorgelina
artículos
Título:
Contribution of a harpin protein from Xanthomonas axonopodis pv. citri to pathogen virulence
Autor/es:
SGRO, G:; FICARRA, F.A.; DUNGER, G.; SCARPECI, T.; VALLE, E.; CORTADI, A.; ORELLANO, E; GOTTIG, N.; JORGELINA OTTADO
Revista:
MOLECULAR PLANT PATHOLOGY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2012 vol. 13 p. 1047 - 1059
ISSN:
1464-6722
Resumen:
Xanthomonas axonopodis pv. citri (Xac), the bacterium that
causes citrus canker, contains a gene in the hrp [for hypersensitive
response (HR) and pathogenicity] cluster that encodes a harpin
protein called Hpa1. Hpa1 produced HR in the nonhost plants
tobacco, pepper and Arabidopsis, whereas, in the host plant citrus,
it elicited a weak defence response with no visible phenotype.
Co-infiltrations of Xac with or without the recombinant Hpa1
protein in citrus leaves produced a larger number of cankers in the
presence of the protein. To characterize the effect of Hpa1 during
the disease, an Xac(delta)hpa1 mutant was constructed, and infiltration
of this mutant caused a smaller number of cankers. In addition, the
lack of Hpa1 hindered bacterial aggregation both in solution and
in planta. Analysis of citrus leaves infiltrated with Hpa1 revealed
alterations in mesophyll morphology caused by the presence of
cavitations and crystal idioblasts, suggesting the binding of the
harpin to plant membranes and the elicitation of signalling cascades.
Overall, these results suggest that, even though Hpa1 elicits
the defence response in nonhost plants and, to a lesser extent, in
host plants, its main roles in citrus canker are to alter leaf mesophyll
structure and to aggregate bacterial cells, and thus increase
virulence and pathogen fitness.We expressed the N-terminal and
C-terminal regions and found that, although both regions elicited
HR in nonhost plants, only the N-terminal region showed
increased virulence and bacterial aggregation, supporting the role
of this region of the protein as the main active domain.