Linkage and Association Mapping of Seed Size and Shape in Lentil

• Other Authors: Bett, Kirstin
• Language: English
• Published: 2013
• Subjects: Quantitative Trait Loci (QTL) Linkage Disequilibrium (LD) Marker-Assisted Selection (MAS)
• Online Access: http://hdl.handle.net/10388/ETD-2013-04-990

The seed size and shape of lentil are important traits because they determine the market class, cooking time, and can influence quality and yield of milled lentils. Understanding the genetic control of seed size and shape can help breeders develop varieties with improved seed size and shape characteristics such as seed diameter, seed thickness and seed plumpness. The objectives were to determine the heritability of seed size and shape and identify the genomic regions controlling these traits. This involved i) developing a linkage map for the LR-18 population (CDC Robin x 964a-46) using a recently developed single nucleotide polymorphism (SNP) assay; ii) analyzing the LR-18 population for seed size and shape QTLs; iii) analyzing an association mapping panel for seed size and shape QTLs. Phenotyping trials were grown at two different locations in Saskatchewan, Canada. The mapping population was grown in two different years while the association panel was only grown in one. Seed diameter and thickness were measured using sieves and this data were used to calculate seed plumpness. Days to flowering was also recorded to determine if it had any effect on seed size or shape. A linkage map consisting of 537 SNPs, 10 SSRs and 4 morphological markers on seven linkage groups was constructed and used for the QTL analysis. The heritability estimates were high for seed diameter and seed plumpness (0.92 and 0.94, respectively) while for seed thickness and days to flowering they were more moderate (0.60 and 0.45, respectively). QTL analysis revealed QTLs on five of the seven linkage groups. The association mapping study revealed similar heritability estimates of 0.97, 0.62, 0.94, and 0.62 for seed diameter, seed thickness, seed plumpness and flowering time, respectively. There were 31 different significant marker trait associations, however only 5 of those were significant for both locations. Four of those five markers did not map in the LR-18 linkage map so their genomic locations are still to be determined. Results showed that there are key regions in the genome that control seed size and shape and flowering time in lentil. These markers could be used for marker-assisted selection or for further candidate gene analysis.