Abstract
The antifungal protein (AFP) produced by Aspergillus giganteus, encoded by the afp gene, has been used to confer resistance against a broad range of fungal pathogens in several crops. In this research, transgenic olive plants expressing the afp gene under the control of the constitutive promoter CaMV35S were generated and their disease response against two root infecting fungal pathogens, Verticillium dahliae and Rosellinia necatrix, was evaluated. Embryogenic cultures derived from a mature zygotic embryo of cv. ‘Picual’ were used for A. tumefaciens transformation. Five independent transgenic lines were obtained, showing a variable level of afp expression in leaves and roots. None of these transgenic lines showed enhanced resistance to Verticillium wilt. However, some of the lines displayed a degree of incomplete resistance to white root rot caused by R. necatrix compared with disease reaction of non-transformed plants or transgenic plants expressing only the GUS gene. The level of resistance to this pathogen correlated with that of the afp expression in root and leaves. Our results indicate that the afp gene can be useful for enhanced partial resistance to R. necatrix in olive, but this gene does not protect against V. dahliae.
Highlights
Olive (Olea europaea L.), the only species producing edible fruits within the Oleaceae family, is one of the most ancient cultured plants probably domesticated from wild olives (O. europaea L. subsp. sylvestris) around 6000–5000 BC (López-Escudero and Mercado-Blanco, 2011)
The aim of the present study was to investigate if the ectopic expression of the afp gene from A. giganteus enhances resistance to Verticillium wilt caused by the D V. dahliae pathotype and White root rot caused by R. necatrix in olive plants
More than 2400 globular somatic embryos (SE) from line P1 were inoculated with the A. tumefaciens AGL1 disarmed strain carrying the pBIN61 binary vector, in two independent experiments
Summary
Olive (Olea europaea L.), the only species producing edible fruits within the Oleaceae family, is one of the most ancient cultured plants probably domesticated from wild olives (O. europaea L. subsp. sylvestris) around 6000–5000 BC (López-Escudero and Mercado-Blanco, 2011). Verticillium dahliae Kleb., the causal agent of the Verticillium wilt disease, is considered the main soil-borne pathogen threatening olive production worldwide (López-Escudero and Mercado-Blanco, 2011; Jiménez-Díaz et al, 2012; Keykhasaber et al, 2017). This fungus causes two disease syndromes, namely defoliating (D) and nondefoliating (ND) (Navas-Cortés et al, 2008; Jiménez-Díaz et al, 2012). Slow decline is recognized mainly by flower mummification and necrosis of inflorescences together with chlorosis and necrosis of leaves that develop on individual branches
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