Laurine Lambelin is a PhD student at the University of Angers, France, working with the Genetics and Diversity of Ornamental Plants team at the Institute of Research in Horticulture and Seeds. Her research is focused on the resistance of roses to black spot disease, caused by the hemibiotrophic fungus Diplocarpon rosae. Black spot is one of the main foliar diseases of garden roses. Resistant varieties have proven to be an efficient alternative to the use of fungicides, but the genetic basis for resistance is not well known, and understanding the underlying mechanisms of resistance is essential for the effective and durable deployment of resistant varieties. Analysis of an F1 progeny from a cross between the susceptible genotype Rosa chinensis ‘Old Blush’ and a hybrid of Rosa wichurana (RW) showed that its resistance mainly results from the combined action of two quantitative trait loci (QTLs), located on linkage groups 3 and 5. Characterizing the interaction of each of these QTLs and their combination with D. rosae at the molecular level is crucial in cloning the underlying genes and identifying markers for their use in breeding. The first step in deciphering the mechanisms associated with these two QTLs is to narrow their confidence intervals. To do this, the F1 progeny was expanded and genotyped with a reduced set of SNP markers, followed by further QTL detection. To better understand the action of each QTL and their combinations, individuals from the F1 progeny have been selected that present either one of the QTLs or a combination of both. Based on their level of resistance and genotype, some of these individuals were chosen for RNA sequencing of the initial stages of the rose-D. rosae interaction. Comparison of their reactions at the transcriptomic level will give insights into the molecular processes underlying each QTL. Further examination of the genomic variants between the two haplotypes of RW will also be useful for identifying the mechanisms associated with black spot resistance. Since members of the RW species have been widely used in breeding programs, understanding how their resistance works will enable breeders to combine these QTLs with other sources of resistance, creating more durable black spot resistance in roses.
Laurine Lambelin won the ISHS Prof. Jens Wünsche Young Minds Award for the best poster presentation at the International Symposium on Ornamental Horticulture for the Service of Society at EHC2024 in Romania in May 2024.
Laurine Lambelin, IRHS-UMR1345, Université d’Angers, INRAE, Institut Agro, SFR 4207 QuaSaV, 49071 Beaucouzé, France, e-mail: laurine.lambelin@gmail.com
The article is available in Chronica Horticulturae