EXPRESSION OF CANDIDATES AVRVG GENES DURING APPLE SCAB INFECTION

In gene-for-gene interactions, avirulence genes interact, directly or not, with host resistance genes, triggering several defense mechanisms and resulting in no disease development.
This kind of interaction was shown to occur in many host-pathogen relationships, including the one between Malus x domestica and Venturia inaequalis, the causal agent of apple scab.
In the specific interaction between the host cultivar ‘Golden Delicious’ and V. inaequalis race 7, both the resistance gene Vg and the avirulence gene AvrVg have been identified and their map position determined in the host and in the pathogen genome respectively.
Focusing on the fungal avirulence gene AvrVg, we constructed a genomic library of an AvrVg avirulent isolate and performed a chromosome walking, isolating and sequencing a 330 kb genomic region carrying this gene.
Four different in silico gene predictions were performed on the genomic sequence resulting in a total of 169 genes grouped in 60 coding regions, some predicted by all four predictions to encode for the same identical protein and other regions where differences between the different predictions were found in the splicing sites.
A second analysis was performed by software, allowing the identification of 40 regions coding for genes predicted to be secreted extracellularly, either by signal peptide or by non-classical secretion, these being the most common feature among avirulence genes.
The next step toward identification of the real avirulence gene is the investigation of the expression of such candidate avirulence gene identified in silico as well as the examination of their possible alleles in virulent isolates.
The results of the in silico gene prediction in the AvrVg region and preliminary results of candidate avirulence gene expression experiments will be presented.

XII EUCARPIA Symposium on Fruit Breeding and Genetics

G.A.L. Broggini, F. Di Gennaro, B. Le Cam, L. Parisi, C. Gessler, A. Patocchi

cloning, avirulence, gene prediction, ‘Golden Delicious’

https://doi.org/10.17660/ActaHortic.2009.814.131