Isolation and diversity analysis of resistance genes analogues (RGAs) from cultivated and wild strawberries.

MARTÍNEZ ZAMORA, M. G.; CASTAGNARO, A. P.; DÍAZ RICCI, JUAN CARLOS

MOLECULAR GENETICS AND GENOMICS

Springer Berlin

Lugar: Berlín; Año: 2004 vol. 272 p. 480 - 487

1617-4615

Abstract Degenerate oligonucleotide primers, designed based on conserved regions of Nucleotide Binding Site (NBS) domains from previously cloned plant resistance genes, were used to isolate Resistance Gene Analogues (RGAs) from wild and cultivated strawberries. Seven distinct families of RGAs of the NBS-LRR type were identi.ed from two related wild species, Fragaria vesca and F. chiloensis, and six di.erent Fragaria · ananassa cultivars. With one exception (GAV-3), the deduced amino acid sequences of strawberry RGAs showed strong similarity to TIR (Toll Interleukin I Receptor)- type R genes from Arabidopsis, tobacco and .ax, suggesting the existence of common ancestors. GAV-3 seemed to be more closely related to the non-TIR type. Further studies showed that the recombination level and the ratio of non-synonymous to synonymous substitutions within families were low. These data suggest that NBS-encoding sequences of RGAs in strawberry are subject to a gradual accumulation of mutations leading to purifying selection, rather than to a diversifying process. The present paper is the .rst report on RGAs in strawberry.