Genomic cloning and linkage mapping of the Mal d 1 (PR-10) gene family in apple (Malus domestica)

Abstract

Fresh apples can cause birch pollen-related food allergy in northern and central European populations, primarily because of the presence of Mal d 1, the major apple allergen that is cross-reactive to the homologous and sensitizing allergen Bet v 1 from birch. Apple cultivars differ significantly in their allergenicity. Knowledge of the genetic basis of these differences would direct breeding for hypoallergenic cultivars. The PCR genomic cloning and sequencing were performed on two cultivars, Prima and Fiesta, which resulted in 37 different Mal d 1 gDNA sequences. Based on the mapping of sequence-specific molecular markers, these sequences appeared to represent 18 Mal d 1 genes. Sixteen genes were located in two clusters, one cluster with seven genes on linkage group (LG) 13, and the other cluster with nine genes on the homoeologous LG 16. One gene was mapped on LG 6, and one remained unmapped. According to sequence identity, these 18 genes could be subdivided into four subfamilies. Subfamilies I-III had an intron of different size that was subfamily and genespecific. Subfamily IV consisted of 11 intronless genes. The deduced amino acid sequence identity varied from 65% to 81% among subfamilies, from 82% to 100% among genes within a subfamily, and from 97.5% to 100% among alleles of one gene. This study provides a better understanding of the genetics of Mal d 1 and the basis for further research on the occurrence of allelic diversity among cultivars in relation to allergenicity and their biological functions.

Identification of a major QTL together with several minor additive or epistatic QTLs for resistance to fire blight in apple in two related progenies

“…Therefore, the results have to be seen as convergent indications of the probable involvement of epistasis in fire blight resistance in apple. Interestingly, the region identified three times on LG16 also co-localizes with a gene cluster for pathogenesis-related proteins of the PR10 family (Gao et al 2005). Such genes can be considered to be candidate genes putatively involved in the control of fire blight.…”

The RNA Hydrolysis and the Cytokinin Binding Activities of PR-10 Proteins Are Differently Performed by Two Isoforms of the Pru p 1 Peach Major Allergen and Are Possibly Functionally Related

“…Recent data indicated that a Pru p 1.01 isoform, named Pru p 1.06D according to its sequence identity (Gao et al, 2005;Chen et al, 2008), is one of the most abundantly expressed genes among the ripe peach mesocarp transcriptome (Trainotti et al, 2006). Pru p 1.06D shows high sequence identity (73%) to Pru p Figure 5.…”

Genomic characterization and linkage mapping of the apple allergen genes Mal d 2 (thaumatin-like protein) and Mal d 4 (profilin)

“…They are the same cultivars that had been chosen for mapping Mal d 1 (Gao et al 2005a) and Mal d 3 (Gao et al 2005b). Two primer pairs located in the untranslated region (UTR) were used to amplify the targeted Mal d 2 genomic sequences (Table 1).…”