CDNA-NBS PROFILING OF HORTENSIA RGA-LIKE GENES RESPONSIVE TO LEAF SPOT FUNGAL INFECTION.

CDNA-NBS PROFILING OF HORTENSIA RGA-LIKE GENES RESPONSIVE TO LEAF SPOT FUNGAL INFECTION. WOODROW P., KAFANTARIS I., IANNUZZI F., MIRTO A., FUGGI A. AND CARILLO P. Dipartimento di Scienze e Tecnologie Ambientali Biologiche e Farmaceutiche, Seconda Università degli Studi di Napoli, via Vivaldi 43, 81100 Caserta, Italy. Keywords: biotic stress, resistance genes, nbs profiling, leaf spot, hortensia. Hydrangeas are susceptible to leaf spot fungus Cercospora hydrangeae. Fungal spores germinate quickly and spread over the plant leaves under warm and rainy weather forming small purple or brown spots. Although Hydrangea plants are not killed by leaf spot, it reduces the flowering and plant vigor decreasing the market value of the plants. The aim of our study was to isolate and characterize Hortensia resistance (R) gene transcripts under C. hydrangeae fungus infection and investigate their expression profile and evolutionary relationships. The majority of disease R-genes in plants encode nucleotide-binding site leucine-rich repeat (NBS-LRR) proteins. A cDNA-NBS strategy was carried out using as template cDNAs isolated from control and infected plant leaves. The cDNA-NBS profiling gave an excellent bands reproducibility. Twenty new transcripts corresponding to NBS-LRR proteins were identified only in infected plants. Their phylogenetic analysis revealed that most of them evolved through concerted evolution probably due to a selective pressure from a certain pathogen and/or genetic evolutionary events such as gene conversion, crossing-over, duplication and diversifying selection.