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Title: Reaction of detached leaves of different varieties of sweet orange (Citrus sinensis L. Osbeck) to inoculation with Xanthomonas citri subsp. citri (ex Hasse) Gabriel et al.

Author
item GONCALVES-ZULIANI, ALINE - University Of Maringa
item KERN, KATIA - University Of Maringa
item BELASQUE JUNIOR, JOSE - Universidad De Sao Paulo
item ZANUTTO, CARLOS - University Of Maringa
item HASHIGUTI, HERALDO - University Of Maringa
item NAKAMURA, CELSO - University Of Maringa
item Bock, Clive
item NUNES, WILLIAM - University Of Maringa

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2015
Publication Date: 11/1/2015
Citation: Goncalves-Zuliani, A.M., Kern, K.A., Belasque Junior, J., Zanutto, C.A., Hashiguti, H.T., Nakamura, C.V., Bock, C.H., Nunes, W.M. 2015. Reaction of detached leaves of different varieties of sweet orange (Citrus sinensis L. Osbeck) to inoculation with Xanthomonas citri subsp. citri (ex Hasse) Gabriel et al.. Phytopathology. 105(Suppl. 4):S4.51.

Interpretive Summary: Abstract only. JLR

Technical Abstract: Asiatic citrus canker (ACC) (caused by Xanthomonas citri subsp citri, Xcc) is a major disease of citrus in wet tropical and subtropical production regions. Screening for resistance is important to breeding programs. The objective of this study was to evaluate a detached leaf method to compare nine different citrus genotypes that exhibit a range of resistance to ACC, and to contrast infection, colonization and symptom development of the most resistant and most susceptible varieties using Scanning Electron Microscopy (SEM). Inoculation was by needle wounding with Xcc (108 CFU/ml). At 7, 10 and 13 days after inoculation (DAI), lesion diameters were measured. The variety Pera IAC was the most resistant to the pathogen (mean lesion diameter in two experiments = 1.213 and 1.317, respectively). The variety Washington navel was the most susceptible (mean lesion diameter in two experiments = 1.815 and 1.838, respectively), indicating low resistance to Xcc. However, there was variability in lesion size on each cultivar that highlights potential issues with using the pin-prick method compared to other methods used in canker screening. SEM images were taken of lesion development after wounding of the most resistant variety Pera IAC and the most susceptible variety Washington navel at 3, 7 and 14 DAI. Pera IAC had smaller stomatal openings and produced a greater quantity of foliar exudates compared with Washington navel. It is possible that the exudates may contain compounds toxic to Xcc, but further research is required to establish any antibiotic effects of the exudates against citrus canker.