Rice pathogen Xanthomonas oryzae pv. oryzae employs inducible hrp-dependent XopF type III effector protein for its growth, pathogenicity and for suppression of PTI response to induce blight disease

Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is a major disease of rice worldwide. Xoo secretes effector proteins (T3Es) directly into the rice cell through a hrp-encoded specialized type III secretion apparatus to induce blight. We examined the function of XopF, one of the conserv...

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Bibliographic Details
Published in:European journal of plant pathology 2016-02, Vol.144 (2), p.311-323
Main Authors: Mondal, Kalyan K., Verma, Geeta, Manju, Junaid, Alim, Mani, Chandra
Format: Article
Language:English
Subjects:
Agriculture
Allium cepa
Biomedical and Life Sciences
Crop diseases
Ecology
Leaves
Life Sciences
Nicotiana benthamiana
Pathogens
Plant Pathology
Plant Sciences
Proteins
Rice
Xanthomonas oryzae
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Summary:Bacterial blight caused by Xanthomonas oryzae pv. oryzae (Xoo) is a major disease of rice worldwide. Xoo secretes effector proteins (T3Es) directly into the rice cell through a hrp-encoded specialized type III secretion apparatus to induce blight. We examined the function of XopF, one of the conserved effectors in Xoo, using a null mutant developed through a PCR-based homologous recombination strategy. We studied inducible, hrp-dependent expression pattern of xopF. We confirmed that XopF is translocated in rice cytosol through T3SS using adenylate cyclase activity assay. XopF regulate the in planta Xoo growth and suppress PAMP-triggered immune (PTI) response in rice. Xoo wild but not mutant, Xoo ∆xopF produced intense blight lesions upon inoculation using leaf clipping method. Further, Xoo ∆xopF showed significant reduction in planta colonization relative to the wild strain. The relative expression analysis of PTI marker genes, PR10, OsWRKY13, OsRLCK16, and OsFLS2 indicated that these genes were up-regulated 1.5 to 5 fold upon challenge-inoculation with Xoo ∆xopF indicating the role of XopF in suppressing PTI in rice. Xoo ∆xopF mutant induced more callose deposition in infected rice leaves. XopF::EYFP fusion gene product was localized to the plasma membrane when transiently expressed in Nicotiana benthamiana as well as in living onion epidermal cells. Collectively, the present study shows that XopF repress basal PTI response in plants, and thus favours Xoo growth and pathogenicity in rice.
ISSN:0929-1873
1573-8469
DOI:10.1007/s10658-015-0768-7