Usage of the Heterologous Expression of the Antimicrobial Gene afp From Aspergillus giganteus for Increasing Fungal Resistance in Olive

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.

Heterologous Expression of the AtNPR1 Gene in Olive and Its Effects on Fungal Tolerance

“…This strategy could be an advantage for selection, avoiding the excessive stress caused in olive cells by A. tumefaciens inoculation; this approach favors cell proliferation and results in a better appearance of the callus. The transformation efficiency was 0.28%, whereas in other studies carried out in olive using the same type of explant and the hypervirulent A. tumefaciens strain AGL1, transformation rates were higher; for example, Narvaez et al (2018) obtained a 1.5% transformation rate with the antifungal protein afp of Aspergillus giganteus, while with the FTa1 gene from M. truncatula (MtFTa1), it was 2.56% (Haberman et al, 2017). These differences in transformation rates could be explained by the size of the transgene.…”

“…Disease reactions to the D and ND V. dahliae pathotypes of three AtNPR1 transgenic lines as well as the non-transgenic control P1, which is highly susceptible to this pathogen (Narvaez et al, 2018), were assessed as previously described (Jiménez-Fernández et al, 2016). Monosporic V. dahliae isolates from cotton (V-138: D pathotype, race 2) and olive (V-1242: ND pathotype, race 2; and V-1558: ND pathotype, race 1) (Jiménez-Díaz et al, 2017) were used.…”

Three Antifungal Proteins From Penicillium expansum: Different Patterns of Production and Antifungal Activity

“…tritici and the leaf rust fungus Puccinia recondite f.sp. tritici ( Oldach et al, 2001 ) and to transgenic olive plants against the root infecting fungal pathogen Rosellinia necatrix ( Narváez et al, 2018 ).…”

Somatic Embryogenesis from Mature Embryos of Olea europaea L. cv. ‘Galega Vulgar’ and Long-Term Management of Calli Morphogenic Capacity

“…Olive transcriptomics, proteomics, and metabolomics [9][10][11][12] have begun to provide indications of candidate genes that may be key to the definition of an interesting phenotype. However, data from these high throughput approaches only has physiological value if the functionality is confirmed, usually by knockout or overexpression of target genes [13][14][15]. Functional validation requires the establishment of in vitro protocols for plant regeneration, where cells integrating the foreign DNA can regenerate an entirely new plant.…”