Title: Analysis at molecular level of the apple-scab interaction in a resistant and susceptible host This work focused on the study of the expression patterns of genes that may be related with defense responses to apple scab (Venturia inaequalis). This analysis was conducted in a susceptible („Royal Gala‟ seedlings) and a resistant host („Florina‟) by RT-qPCR following artificial inoculations with conidial scab suspensions (using water as control). For the susceptible host, the interaction was analysed at 48, 72 e 96 h, whereas for the resistant host, only the moment of 96 h upon inoculation was studied. Expression pattern analysis of genes related with cuticle (M10) and cell wall synthesis (M9), resistance genes (M6) and genes involved in biotic and abiotic stress responses (M3, N54, N3021), previously identified, showed that these genes are upregulated in infected samples in both genotypes, with higher upregulation levels in the resistant cultivar „Florina‟ (for M9, M10 and N3021). The use of RACE methodology enabled the extension of the known coding sequence of M9 in the 5‟ direction in 851 bp. The analysis of the long sequence reinforced the homology previously established with a gene coding for a Cellulose synthase, involved in cell wall synthesis and that might be related to plant defense response upon apple scab attack.

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia