02034naa a2200277 a 450000100080000000500110000800800410001910000180006024501600007826000090023852011290024765000260137665000320140265000220143465000250145665000220148170000180150370000200152170000220154170000220156370000200158570000170160570000230162270000280164577300830167311358162025-07-07       2025    bl uuuu     u00u1 u    #d1 aDOCEMA, M. L.  aReaction of transgenic ?Hamlin? sweet orange expressing csd1 or d4e1 genes after inoculation with Candidatus Liberibacter asiaticus.h[electronic resource]  c2025  aWe evaluated the response of ?Hamlin? sweet orange plants (Citrus x sinensis L. Osbeck) transformed with the gene encoding the synthetic antimicrobial peptide d4e1, driven by the35S promoter, or with the gene encoding copper-zinc superoxide dismutase (csd1), isolated from Poncirus trifoliata and driven by the Ubiquitin 10 promoter, against Candidatus Liberibacter asiaticus (CLas). The experimental plants were propagated by grafting and then inoculated with CLas-infected budwood. The presence and concentration of CLas were determined in leaf tissues by qPCR six, 12, and 18 months after inoculation (m.a.i.). Callose detection was evaluated in transgenic sweet orange events after pathogen inoculation through epifluorescence analysis. Five transgenic events expressing the csd1 gene and one expressing the d4e1 gene exhibited reduced CLas populations compared to non-transgenic plants and showed no visible symptoms of huanglongbing (HLB), six m.a.i. Moreover, an increase in callose depositionin phloem tissues of some transgenic events may be a defence response to biotic stresses, leading to lower CLas populations.  aantimicrobial peptide  aCandidatus liberibacter spp  aCitrus x sinensis  asuperoxide dismutase  atransgenic plants1 aMORAES, T. S.1 aATT??LIO, L. B.1 aPIEDADE, S. M. S.1 aMARQUES, J. P. R.1 aSTIPP, L. C. L.1 aHARAKAVA, R.1 aFREITAS-AST??A, J.1 aMOUR??O FILHO, F. A. A.  tThe Journal of Horticultural Science and Biotechnology, London, p. 1-13, 2025.