Apple Contains Receptor-like Genes Homologous to the Cladosporium fulvum Resistance Gene Family of Tomato with a Cluster of Genes Cosegregating with Vf Apple Scab Resistance

Abstract

Scab caused by the fungal pathogen Venturia inaequalis is the most common disease of cultivated apple (Malus x domestica Borkh.). Monogenic resistance against scab is found in some small-fruited wild Malus species and has been used in apple breeding for scab resistance. Vf resistance of Malus floribunda 821 is the most widely used scab resistance source. Because breeding a high-quality cultivar in perennial fruit trees takes dozens of years, cloning disease resistance genes and using them in the transformation of high-quality apple varieties would be advantageous. We report the identification of a cluster of receptor-like genes with homology to the Cladosporium fulvum (Cf) resistance gene family of tomato on bacterial artificial chromosome clones derived from the Vf scab resistance locus. Three members of the cluster were sequenced completely. Similar to the Cf gene family of tomato, the deduced amino acid sequences coded by these genes contain an extracellular leucine-rich repeat domain and a transmembrane domain. The transcription of three members of the cluster was determined by reverse transcriptionpolymerase chain reaction to be constitutive, and the transcription and translation start of one member was verified by 5' rapid amplification of cDNA ends. We discuss the parallels between Cf resistance of tomato and Vf resistance of apple and the possibility that one of the members of the gene cluster is the Vf gene. Cf homologs from other regions of the apple genome also were identified and are likely to present other scab resistance genes.

Venturia inaequalis resistance in local Spanish cider apple germplasm under controlled and field conditions

“…The presence of resistance gene Rvi6 (Vinatzer et al 2001) in local cultivars that showed high resistance to apple scab and fire blight (cultivars 1.1.9, 1.1.20, 2.1.1, 2.1.14, 2.1.21, 3.1.50, 3.1.75, 3.1.80, 3.1.87, 3.1.100, 5.1.23, 5.1.66) was investigated by PCR amplification using the Rvi6-specific primers T1-For (5 0 -CA-ATGCCTTACGTGGTGAAA-3 0 ) and RT2-Rev (5 0 -CAGGGATTCCAGCCAATCTA-3 0 ) at a final concentration of 0.8 lM. The PCR reactions contained 50 ng of purified plant genomic DNA (Lodhi et al 1994) and consisted of one cycle of 10 min at 94°C, followed by 35 cycles of 94°C for 1 min, 58°C for 1 min and 72°C for 2 min, finishing with a cycle of 10 min at 72°C.…”

Molecular markers linked to the apple scab resistance gene Vbj derived from Malus baccata jackii

“…Among these genes, however, only Vf has been intensively studied. A positional cloning project led to the identification in the Vf region of a cluster of genes homologous to the Cf resistance genes of tomato and consequently called HcrVfs (homologues to the Cladosporium fulvum resistance genes of the Vf region, Patocchi et al 1999a, b;Vinatzer et al 2001). One of these genes, HcrVf2, when introduced into the susceptible cultivar Gala, conferred apple scab resistance to the transgenic plants, proving the identification of the first apple scab resistance gene (Barbieri et al 2003;Belfanti et al 2004).…”

Phylogenomic Analysis of the Receptor-Like Proteins of Rice and Arabidopsis

“…Characterized RLP genes involved in resistance include the Cf genes from tomato (Lycopersicon esculentum) that confer resistance against the fungal pathogen Cladosporium fulvum (Jones et al, 1994;Dixon et al, 1996Dixon et al, , 1998Thomas et al, 1997), tomato Ve genes (Kawchuk et al, 2001), apple (Malus domestica) HcrVf2 (Vinatzer et al, 2001), Arabidopsis (Arabidopsis thaliana) RPP27 (Tö r et al, 2004), and tomato LeEIX1 and LeEIX2 (Ron and Avni, 2004). Developmental RLPs in Arabidopsis include TMM (Yang and Sack, 1995;Nadeau and Sack, 2002), which is involved in stomatal patterning, and CLAVATA2 (CLV2; Jeong et al, 1999) and its maize (Zea mays) ortholog FASCIATED EAR2 (FEA2; Taguchi-Shiobara et al, 2001), which are involved in meristem development.…”