Genomic cloning and linkage mapping of the Mal d 1 (PR-10) gene family in apple (Malus domestica).
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 gene-specific. 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.
Gao
Z S
ZS
Allergy Consortium Wageningen, Wageningen University and Research Centre, P.O. Box 16, 6700AA Wageningen, The Netherlands.
van de Weg
W E
WE
Schaart
J G
JG
Schouten
H J
HJ
Tran
D H
DH
Kodde
L P
LP
van der Meer
I M
IM
van der Geest
A H M
AH
Kodde
J
J
Breiteneder
H
H
Hoffmann-Sommergruber
K
K
Bosch
D
D
Gilissen
L J W J
LJ
D000485:Allergens / Q000235:genetics*; D000595:Amino Acid Sequence; D052179:Antigens, Plant; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D016000:Cluster Analysis; D017931:DNA Primers; D005819:Genetic Markers / Q000235:genetics; D027845:Malus / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
D000485:Allergens; D052179:Antigens, Plant; D017931:DNA Primers; D005819:Genetic Markers; C095551:MALD1 protein, Malus domestica; D010940:Plant Proteins