Molecular analysis and visualization of adventitious root formation in rose

David Wamhoff is a PhD candidate at Leibniz University Hannover, Institute for Horticultural Production Systems, Section Woody Plant and Propagation Physiology (section head: Prof. Dr. Traud Winkelmann), studying the potential genetic reasons for differences in adventitious root (AR) formation in rose. Roses are the most valuable ornamental plants spanning multiple market segments worldwide (cut roses, garden roses, and miniature roses). However, garden and cut roses are mainly propagated via laborious and costly methods like grafting, budding, or stenting, and not by time- or cost-saving propagation such as cuttings. This is due to the genetic differences regarding the ability to form AR. The complex process of AR formation is not fully understood and in the case of rose, genetic factors causing differences in rooting ability have not yet been identified. The aim of this project was to determine the genetic differences in AR formation by genome wide association studies (GWAS) for different formation-related traits. Moreover, molecular markers will be developed to select genotypes with the ability to form AR. This would enable breeders to improve rooting ability in roses and establish cutting propagation for all market segments. This project made use of the valuable genetic rose collections held by the Molecular Plant Breeding section at Leibniz University Hannover (section head: Prof. Dr. Thomas Debener). For these collections, genotypic marker information based on single nucleotide polymorphisms (SNPs) of the WagRhSNP 68k Axiom® SNP array was available. Cuttings of 96 garden and 96 cut roses were phenotyped in vivo for different AR formation-related traits in 2020 and 2021. Phenotypic data was linked to the genotypic SNP data to perform GWAS. A promising SNP was identified, which showed a significant association between different AR formation traits and SNP allele dosage. Based on these results, kompetitive allelic specific PCR (KASP) markers were developed. The markers will be validated in an independent rose population.

David Warmhoff won the ISHS Young Minds Award for the best oral presentation at the International Symposium on Innovation in Ornamentals: from Breeding to Market at IHC2022 in France in August 2022.

David Wamhoff, Leibniz University Hannover, Faculty of Natural Sciences, Institute of Horticultural Production Systems, Section Woody Plant and Propagation Physiology, Herrenhäuser Str. 2, 30451 Hannover, Germany, e-mail: wamhoff@baum.uni-hannover.de

The article is available in Chronica Horticulturae