A fruit firmness QTL identified on linkage group 4 in sweet cherry (Prunus avium L.) is associated with domesticated and bred germplasm

Lichun Cai,Teresa Barreneche,Amy Iezzoni,José Quero-García,Elisabeth Dirlewanger,Christopher Saski

doi:10.1038/s41598-019-41484-8

Lichun Cai, Teresa Barreneche + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-41484-8

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Abstract

Fruit firmness is an important market driven trait in sweet cherry (Prunus avium L.) where the desirable increase in fruit firmness is associated with landrace and bred cultivars. The aim of this work was to investigate the genetic basis of fruit firmness using plant materials that include wild cherry (syn. mazzard), landrace and bred sweet cherry germplasm. A major QTL for fruit firmness, named qP-FF4.1, that had not previously been reported, was identified in three sweet cherry populations. Thirteen haplotypes (alleles) associated with either soft or firm fruit were identified for qP-FF4.1 in the sweet cherry germplasm, and the “soft” alleles were dominant over the “firm” alleles. The finding that sweet cherry individuals that are homozygous for the “soft” alleles for qP-FF4.1 are exclusively mazzards and that the vast majority of the bred cultivars are homozygous for “firm” alleles suggests that this locus is a signature of selection. Candidate genes related to plant cell wall modification and various plant hormone signaling pathways were identified, with an expansin gene being the most promising candidate. These results advance our understanding of the genetic basis of fruit firmness and will help to enable the use of DNA informed breeding for this trait in sweet cherry breeding programs.

Highlights

Sweet cherry (Prunus avium L.) is an important fruit crop in temperate regions and fresh fruit is highly valued
Genome-wide transcriptional dynamics from developing fruit between flowering and maturity at 14 time points were investigated and the results suggested tight developmental regulation of genes functioning in diverse processes such as sugar transport, lipid metabolism and cell wall rearrangement related to changes in fruit firmness[15]
The objectives of this study were to (1) identify and characterize the QTL(s) for fruit firmness segregating in an F1 sweet cherry population, (2) explore whether the QTL identified is associated with the firmness that accompanied sweet cherry domestication and breeding, and the presence of softer fruit exhibited by sour cherry, and (3) identify candidate genes for fruit firmness within the QTL region

Summary

Introduction

Sweet cherry (Prunus avium L.) is an important fruit crop in temperate regions and fresh fruit is highly valued. Sweet cherry cultivation in the Jerte Valley, Extremadura, Spain, reported for the first time in 1352, was based on farmer’s selection of local cultivars with improved quality attributes, including firmer fruit[3] Cherry cultivation in this region grew significantly during the XIXth century, and was mainly based on four very firm cultivars harvested stemless, which were traditionally known as ‘Picotas’ including ‘Ambrunés’, ‘Pico Negro’, ‘Pico www.nature.com/scientificreports/. At a period when no modern transportation systems existed in Spain, cherries were transported with mules from this valley to the country’s capital, Madrid, a several day journey, and consumer demand suggested that the fruit still kept acceptable quality Another example of a relatively old firm cultivar is ‘Bing’, which was selected from a seedling of ‘Black Republican’ in 1875 in Oregon, USA4. This cultivar was heavily used as a parent in the INRA breeding program, leading to many new cultivars, such as ‘Folfer’, ‘Ferdouce’, ‘Fertille’ or ‘Ferdiva’[5]

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