Genome-Wide Association Mapping of Flowering and Ripening Periods in Apple

Area of Science:

• Plant genetics
• Horticultural science
• Genomics

Background:

• Understanding the genetic basis of flowering and ripening is crucial for breeding adaptive apple cultivars.
• Apple phenology significantly impacts cultivation success and adaptation to different growing regions.

Purpose of the Study:

• To decipher the genetic control of flowering and ripening periods in apple using Genome-Wide Association Studies (GWAS).
• To identify candidate genes and genomic regions associated with these phenological traits.
• To explore the influence of geographic origin on trait variation and genetic selection.

Main Methods:

• A large-scale European Genome-Wide Association Study (GWAS) was conducted on 1,168 apple genotypes.
• High-density SNP genotyping was performed using the Axiom®Apple 480 K SNP array.
• Multi-locus mixed models (MLMM) were employed to analyze GWAS data, accounting for population structure and relatedness.

Main Results:

• GWAS identified significant SNPs associated with flowering (chromosome 9) and ripening periods (chromosomes 3, 10, and 16), explaining 8.9% and 17.2% of phenotypic variance, respectively.
• Allelic heterogeneity and differential selection based on geographic origin were observed.
• Candidate genes, including those encoding NAC and MADS domain transcription factors, were identified within associated genomic regions, showing microsynteny with peach.

Conclusions:

• Association genetics effectively elucidates the genetic control of key horticultural traits in apple.
• The identified SNPs and candidate genes provide valuable resources for marker-assisted breeding strategies to develop improved apple cultivars.
• Findings highlight the interplay between genotype, geographic origin, and phenological adaptation in apple.