Skip to main content
ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Production and Genetic Improvement Research Unit » Research » Publications at this Location » Publication #420999
Research Project: Genetic Improvement of Blackberry, Red and Black Raspberry, and Blueberry

Location: Horticultural Crops Production and Genetic Improvement Research Unit

Title: Genetic control of prickles in tetraploid blackberry

Author
item JOHNS, CARMEN - University Of Arkansas
item SILVA, ALEXANDER - University Of Arkansas
item CHIZK, T. MASON - University Of Arkansas
item NELSON, LACY - University Of Arkansas
item CLARK, JOHN - University Of Arkansas
item ARYAL, RISHI - North Carolina State University
item ASHRAFI, HUDSON - North Carolina State University
item THOMPSON, ELLEN - Hortifrut
item Hardigan, Michael
item WORTHINGTON, MARGARET - University Of Arkansas

Submitted to: G3: Genes, Genomes, Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/2/2025
Publication Date: 3/20/2025
Citation: Johns, C.A., Silva, A.T., Chizk, T., Nelson, L., Clark, J.R., Aryal, R., Ashrafi, H., Thompson, E., Hardigan, M.A., Worthington, M. 2025. Genetic control of prickles in tetraploid blackberry. G3: Genes, Genomes, Genetics. 15(6). Article jkaf065. https://doi.org/10.1093/g3journal/jkaf065.
DOI: https://doi.org/10.1093/g3journal/jkaf065

Interpretive Summary: Blackberry prickles, commonly referred to as thorns, are considered a negative trait for production of this specialty fruit crop due to creating an impediment for plant training and harvest, and their potential to damage fruit during development and create a source of contamination in harvested fruit loads. The main source of genetically prickle-free (thorn-less) plants in fresh market erect and semi-erect blackberries is ‘Merton Thornless’, a recessive mutation. This study physically and genetically maps the locus containing the ‘Merton Thornless’ mutation to a large haplotype block on the distal arm of chromosome 4 in blackberry. The results of this study will assist in future molecular breeding of thorn-less blackberries by providing candidate genes and elucidating the challenges around this locus, namely, low recombination within a large haplotype block, which will require further exploration using rare recombinants or induced knockout mutations in and around candidate genes.

Technical Abstract: Prickle-free blackberry (Rubus subgenus Rubus) canes are strongly preferred by growers due to food and worker safety concerns and damage to fruit from mechanical injury by prickles. This project was conducted to identify the genetic region responsible for prickle-free canes derived from the recessive ‘Merton Thornless’ source in autotetraploid blackberry using a genome-wide association study, develop diagnostic KASP markers for prickle-free canes, and determine the effects of allele dosage at the prickle-free locus on prickle density in two biparental populations. The prickle locus was located on chromosome Ra04 from 30.48 to 36.04 Mb in an extensive LD block, with the peak SNP located at 33.64 Mb. Two diagnostic KASP markers were developed that correctly predicted the phenotype of 97% and 96% of 626 diverse fresh-market blackberry genotypes from multiple breeding programs, respectively. Allele dosage at the prickle-free locus had a significant impact on prickle density, with duplex prickly genotypes having significantly higher prickle density than simplex genotypes in both biparental populations studied. Five potential candidate genes with functional annotations related to epidermal, trichome, and/or prickle development were identified within the prickle-free locus, but no nonsynonymous polymorphism within these genes were identified.