Increasing fruit size must start with genetics

23 Oct 2024
666

It is certainly the size of the fruit that is the most important characteristic that a cherry must have in order to be appreciated at first sight by consumers. For this reason, considerable genetic research and selection efforts have been made in this crop. At Washington State University (WSU), there is germplasm with good fruit size, a trait whose heritability is reasonably high.

An important genetic locus for cherry fruit size has been identified, but it appears to distinguish mainly between wild and improved phenotypes and may have limited utility in breeding programmes.

The objectives of the collaborative research between Washington State University and Utah State University (USA) were first to identify genetic markers for fruit diameter in germplasm held by WSU. Diameter was chosen as the measure of fruit size due to the availability of data for this trait in the genetic breeding programme.

Secondly, the researchers sought to develop DNA tests for these markers that can be used for assisted selection of young seedlings or parents. Finally, the third objective was to compare the effectiveness of different methods applied in improving fruit size. 

The germplasm used consisted of 247 individuals from two subpopulations. Each of these subpopulations was phenotyped on the basis of fruit diameter for two production seasons.

The subpopulations were first analysed individually and then combined. The results validated that the highly significant locus for cherry fruit size is located on chromosome 2, and was named FWG2a. In both studies, the minor alleles of this locus were associated with smaller fruits, indicating a positive selection pressure for fruit size in the respective populations.

However, the frequencies of the minor alleles were relatively high, indicating that considerable progress still has to be made towards the fixation of favourable alleles in the germplasm, but at the same time there is a good chance to continue selection.

Seven markers were converted into locus-specific assays for validation and use in marker-assisted selection and achieved a concordance rate of ≥97.6%, indicating a high level of agreement between the marker assays and the expected results, which is promising for their application in marker-assisted selection.

These results indicate that association mapping or genomic prediction can be used to select larger fruits in sweet cherry. Although in some genetic backgrounds one or a few locus may be responsible for a large percentage of the phenotypic variation, current and previous studies have routinely identified a relatively large number of markers associated with fruit size that are statistically significant but account for only a small percentage of the phenotypic variation.

In these cases, marker-assisted selection may not be as efficient as desired, especially when heritability is high. In these situations, genomic selection may be an attractive alternative. The results of this study are therefore encouraging and we look forward to further news from WSU.

Source: McCord, P., Crump, W.W., Zhang, Z. et al. Improving fruit size in sweet cherry via association mapping and genomic prediction. Tree Genetics & Genomes 20, 26 (2024). https://doi.org/10.1007/s11295-024-01660-y.
Images: SL Fruit Service

Melissa Venturi
University of Bologna (IT)


Cherry Times - All rights reserved

What to read next

Lightweight agrivoltaics over cherry trees: a pioneering pilot plant in Germany

Covers

18 Apr 2025

A groundbreaking agrivoltaic pilot project in Germany installs lightweight solar panels over cherry orchards using existing weather protection systems—maximizing land use, preserving fruit yields and offering a replicable, sustainable model for smart farming across Europe.

Rapid expansion of Drosophila suzukii is a serious threat

Crop protection

05 Apr 2023

Drosophila suzukii has been rapidly spreading across many countries. The integration of agronomic and sanitation practices besides to the chemical protection can create an unfavourable environment for the phytophagous limiting its presence.

In evidenza

Lebanese cherries aim for EU export with new training

Markets

30 Jun 2025

In Lebanon, cherry farmers and agri-SMEs from the Bekaa Valley and Mount Lebanon are receiving ILO-supported training to meet EU compliance standards. The initiative aims to boost certification, strengthen value chains, and improve access to international export markets.

Jealous Fruits forecasts promising 2025 cherry season in Canada

Production

30 Jun 2025

Jealous Fruits forecasts an excellent 2025 cherry season in British Columbia: harvest begins in July with premium varieties like Regina, Sovereign, and Kordia. A 30–35% increase in late-season production is expected thanks to ideal growing conditions throughout the season.

Tag Popolari