One of the main limiting factors for lemon (Citrus limon Burm. f.) cultivation in the Mediterranean basin is represented by mal secco disease, a severe and difficult-to-control tracheomycosis caused by the mitosporic fungus Plenodomus tracheiphilus. To detect candidate genes linked to tolerance to mal secco, a pedigree-based analysis (PBA) was carried out employing three segregating full-sib populations connected through a pedigree encompassing the known ancestors of lemon. Segregating populations (P1, P2 and P3) were established crossing a common pollen donor, the highly susceptible 'Femminello Siracusano 2Kr' lemon, with three female parents showing different degree of tolerance to the disease: C. latipes (110 accessions; P1), C. clementina (109 accessions; P2) and the 'Interdonato' lemon (120 accessions; P3). Phenotyping was performed, so far, on P1 and P3 by i) in planta inoculation, and ii) observation of the symptoms development in plants held in open fields in an area characterized by high pathogen pressure. In both phenotyping methods, symptom severity was assessed according to empirical evaluation scales leading to the definition of four phenotypic traits (max and mean severity score for both in planta inoculation and open field assay) further employed for the QTL analysis. All accessions were genotyped employing a single-primer enrichment technology (SPET), leading to the definition of 4,836 robust SNPs. A pedigree-based approach was employed for QTL analysis allowing the detection of three significant QTLs located in the linkage groups two, four and six. The identification of significant marker-trait associations will pave the way for the development of molecular tools to assist the breeding of novel lemon cultivars coupling an increased tolerance to mal secco with other desirable traits.
Multiple-family QTL analysis unravels the genetic mechanism of mal secco resistance in lemon ( C. limon Burm. f .)
Catalano, C.;Di Guardo, M.;Cannizzaro, G.;Seminara, S.;La Malfa, S.;Distefano, G.;Gentile, A.
2026-01-01
Abstract
One of the main limiting factors for lemon (Citrus limon Burm. f.) cultivation in the Mediterranean basin is represented by mal secco disease, a severe and difficult-to-control tracheomycosis caused by the mitosporic fungus Plenodomus tracheiphilus. To detect candidate genes linked to tolerance to mal secco, a pedigree-based analysis (PBA) was carried out employing three segregating full-sib populations connected through a pedigree encompassing the known ancestors of lemon. Segregating populations (P1, P2 and P3) were established crossing a common pollen donor, the highly susceptible 'Femminello Siracusano 2Kr' lemon, with three female parents showing different degree of tolerance to the disease: C. latipes (110 accessions; P1), C. clementina (109 accessions; P2) and the 'Interdonato' lemon (120 accessions; P3). Phenotyping was performed, so far, on P1 and P3 by i) in planta inoculation, and ii) observation of the symptoms development in plants held in open fields in an area characterized by high pathogen pressure. In both phenotyping methods, symptom severity was assessed according to empirical evaluation scales leading to the definition of four phenotypic traits (max and mean severity score for both in planta inoculation and open field assay) further employed for the QTL analysis. All accessions were genotyped employing a single-primer enrichment technology (SPET), leading to the definition of 4,836 robust SNPs. A pedigree-based approach was employed for QTL analysis allowing the detection of three significant QTLs located in the linkage groups two, four and six. The identification of significant marker-trait associations will pave the way for the development of molecular tools to assist the breeding of novel lemon cultivars coupling an increased tolerance to mal secco with other desirable traits.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
