01907naa a2200253 a 450000100080000000500110000800800410001902200140006002400550007410000180012924500880014726000090023552011460024465000120139070000210140270000200142370000250144370000220146870000200149070000170151070000200152770000310154777300750157821782492025-08-22       2025    bl uuuu     u00u1 u    #d  a0022-15897 ahttps://doi.org/10.1080/14620316.2025.25159582DOI1 aDOCEMA, M. L.  aReaction of transgenic ‘Hamlin’ sweet orange expressing.h[electronic resource]  c2025  aABSTRACT We 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 the 35S 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 deposition in phloem tissues of some transgenic events may be a defence response to biotic stresses, leading to lower CLas populations.  aLaranja1 aMORAES, T. de S.1 aATTÍLIO, L. B.1 aPIEDADE, S. M. de S.1 aMARQUES, J. P. R.1 aSTIPP, L. C. L.1 aHARAKAVA, R.1 aASTUA, J. de F.1 aMOURÃO FILHO, F. de A. A.  tThe Journal of Horticultural Science and Biotechnology, p.1-13, 2025 .