Genetic diversity in peach [Prunus persica (L.) Batsch] at the University of Florida: past, present and future

Abstract

The University of Florida (UF) stone fruit breeding and genetics program was created in 1952 to develop early ripening stone fruit cultivars with high quality, adaptation to summer rainfall, low chilling requirements, and the ability to withstand high disease pressure. Diverse germplasm sources were used to introduce desirable traits in UF breeding pool. The main objective of this research was to determine the genetic diversity and population structure of the breeding germplasm, and to search for loci under selection. A total of 195 peach genotypes were used: UF cultivars and advanced selections (n=168), cultivars and selections from the UF-UGA-USDA joint breeding effort (n=13), landrace cultivars (n=4), high-chilling cultivars released by NCSU (n=5), and related Prunus (n=5) species. A total of 36 SSR markers distributed across the peach genome amplified 423 alleles. An average of 18 genotypes were detected per marker: A (number of observed alleles) of 11.43, Ae (effective number of alleles) of 2.58, Ho (observed heterozygosity) of 0.4, He (expected heterozygosity) of 0.52, F (Wright's fixation index) of 0.25, and PIC (polymorphism information content) of 0.48. UPGMA cluster analysis based on Nei's genetic distance represented best the known pedigree information for the germplasm pools. Two major groups were observed across the germplasm corresponding to melting and non-melting flesh cultivars/selections. Population structure results supported these two major groups. Several loci closely located to genome regions where different phenotypic traits have been previously mapped were detected to be under selection.

Population Genetic Analysis of Brazilian Peach Breeding Germplasm

“…Similar results associating genetic structure with fruit characteristics were also reported before by other authors LI et al, 2013;CHAVEZ et al, 2014) analyzing peach germplasm. Aranzana et al (2010) identified three main groups: melting flesh peaches, melting flesh nectarines, and non-melting cultivars.…”

“…An average of 8.0 alleles per locus was observed, which is higher than the values reported in previous studies on genetic diversity in peach Chavez et al (2014) reported that a total of 237 alleles were amplified for 168 peach and nectarine cultivars and selections of the University of Florida (UF) peach germplasm using 36 SSR markers. Comparing three SSR markers (BPPCT014, BPPCT017 and CPPCT022) in common with their work, we were able to distinguish an average of 24 genotypes per marker while only 16 genotypes per marker were observed in UF peach germplasm.…”

“…by Chavez et al (2014) in UF peach germplasm: outgroups and landrace germplasm, melting cultivars, and non-melting cultivars.…”

“…Over the last two decades, simple sequence repeat markers (SSRs) have been successfully carried out in peach to assess genetic diversity (DIRLEWANGER et al, 2002;ARANZANA et al, 2003;XIE et al, 2010;BOUHADIDA et al, 2011) and more recently, for population stratification CAO et al, 2012;FONT I FORCADA et al, 2013;LI et al, 2013;CHAVEZ et al, 2014), providing tools for marker-assisted selection (MAS). However, to date the available peach germplasm in Brazil is still underexplored at the molecular level.…”

<i>Endopolygalacturonase</i> Gene Polymorphisms: Asset of the Locus in Different Peach Accessions

“…In peach, availability of different molecular markers allowed to gain information on some 760 Quantitative Trait Loci and Mendelian Trait Loci linked to horticultural and physiological traits such as tree development, pest and disease resistance, flowering, ripening, seed and fruit quality [16] [17].…”