Mapping a candidate gene (MdMYB10) for red flesh and foliage colour in apple.
BACKGROUND
Integrating plant genomics and classical breeding is a challenge for both plant breeders and molecular biologists. Marker-assisted selection (MAS) is a tool that can be used to accelerate the development of novel apple varieties such as cultivars that have fruit with anthocyanin through to the core. In addition, determining the inheritance of novel alleles, such as the one responsible for red flesh, adds to our understanding of allelic variation. Our goal was to map candidate anthocyanin biosynthetic and regulatory genes in a population segregating for the red flesh phenotypes.


RESULTS
We have identified the Rni locus, a major genetic determinant of the red foliage and red colour in the core of apple fruit. In a population segregating for the red flesh and foliage phenotype we have determined the inheritance of the Rni locus and DNA polymorphisms of candidate anthocyanin biosynthetic and regulatory genes. Simple Sequence Repeats (SSRs) and Single Nucleotide Polymorphisms (SNPs) in the candidate genes were also located on an apple genetic map. We have shown that the MdMYB10 gene co-segregates with the Rni locus and is on Linkage Group (LG) 09 of the apple genome.


CONCLUSIONS
We have performed candidate gene mapping in a fruit tree crop and have provided genetic evidence that red colouration in the fruit core as well as red foliage are both controlled by a single locus named Rni. We have shown that the transcription factor MdMYB10 may be the gene underlying Rni as there were no recombinants between the marker for this gene and the red phenotype in a population of 516 individuals. Associating markers derived from candidate genes with a desirable phenotypic trait has demonstrated the application of genomic tools in a breeding programme of a horticultural crop species.
Chagné
David
D
The Horticulture and Food Research Institute of New Zealand (HortResearch) Palmerston North, PB 11030, Manawatu Mail Centre, Palmerston North 4442, New Zealand. DChagne@hortresearch.co.nz
Carlisle
Charmaine M
CM
Blond
Céline
C
Volz
Richard K
RK
Whitworth
Claire J
CJ
Oraguzie
Nnadozie C
NC
Crowhurst
Ross N
RN
Allan
Andrew C
AC
Espley
Richard V
RV
Hellens
Roger P
RP
Gardiner
Susan E
SE
D000872:Anthocyanins / Q000096:biosynthesis; D002874:Chromosome Mapping; D020090:Chromosome Segregation; D020224:Expressed Sequence Tags; D005638:Fruit / Q000235:genetics; D017343:Genes, Plant / Q000235:genetics*; D008040:Genetic Linkage; D027845:Malus / Q000235:genetics*; D010858:Pigmentation / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D020449:Repetitive Sequences, Amino Acid; D014157:Transcription Factors / Q000235:genetics
D000872:Anthocyanins; D014157:Transcription Factors