Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 1.29

DIFFERENTIALLY EXPRESSED GENES IN THE APPLE CULTIVAR FLORINA AFTER SCAB INOCULATION

C. Toller*, c. Gessler**, A. patocchi**, E. Zini*, P. Baldi*, s. passerotti*, M. Komjanc*

*) Istituto Agrario di San Michele all’Adige, via E. Mach 1, 38010 San Michele all’Adige (TN), Italy

**) Swiss Federal Institute of Technology Zurich (ETH) Rämistrasse 101, 8006 Zurich - CH

apple, PCR-Select, differentially expressed genes, apple scab

For years the Agricultural Institute of San Michele all’Adige has been interested in the study of the plant - pathogen interaction in apple and in 2000 it has started a project called “Advanced Biology Applied to Grape, Apple and Salmons” financed by the Caritro foundation.

Our contribution in this project is the isolation and characterisation of differentially expressed genes and sequences associated to signal transduction pathways involved in apple defence mechanisms.

In this study the PCR-Select technique is used (kit “PCR-Select cDNA Subtraction” by Clontech), a method already known from literature to be very useful for the identification and isolation of rare and differentially expressed genes.

The current study is turned to the molecular analysis in order to identify defence and signal transduction genes after scab inoculation and salicylic acid treatment (a second messenger associated with SAR - Systemic Acquired Resistance) in Florina apple leaf tissue.

In this way we will be able to find out the differences and similarities between the two signal transduction pathways.

We have isolated 1152 colonies; among them we have selected 280 positive clones by Southern analysis and 203 of them have been sequenced.

The results revealed 10 most frequent sequences which showed a very high homology ( > 85%) with known sequences in blast analysis.

All these genes have been studied by Northern analysis.

The two most representative genes were a 14 -3 - 3 protein and a Mal d 1, with a frequency respectively of 22 % and 8 % on the total of the sequenced clones. Both of them were strongly up-regulated after 48 h of treatment.

We have then isolated two different sequences of chitinase (class II and class V) that by Northern analysis revealed a differential expression, the first one was up-regulated after the treatment with the fungal pathogen while the second one was down-regulated.

This result is consistent with two papers in which it has been demonstrated how some isoforms of chitinase could be up-regulated while other down-regulated after the same treatment.

Our next steps will be to obtain the full length of these genes and then to study their expression considering different times after scab inoculation to detect the pattern of activation of each gene in the plant.