Abstract
Fresh-cut lettuce is popular, but highly perishable product. Genetic studies of two bi-parental populations derived from crossing parents with rapid and slow rates of deterioration showed that the deterioration rate is a heritable trait (broad spectrum heritability, H2 of 0.56–0.87). The major genetic determinant of the deterioration rate in both populations was the quantitative trait locus (QTL), qSL4, located on linkage group 4. This QTL explained 40–74% of the total phenotypic variation of the trait in the two populations. Saturating the qSL4 region with single-nucleotide (SNP) markers allowed detection of six haplotypes in a set of 16 lettuce accessions with different rates of deterioration. Three of the haplotypes were always associated with very rapid rates of deterioration, while the other three haplotypes were associated with slow rates of deterioration. Two SNPs located 53 bp apart were sufficient to separate the 16 accessions into two groups with different rates of deterioration. The accuracy of markers-trait association was subsequently tested on 350 plants from seven F2 families that originated from crossing parents with different rates of deterioration. The H2 of deterioration rate in these seven families ranged from 0.64 to 0.90. The SNP-based analysis accurately identified individuals with rapid, intermediate, and slow rates of deterioration in each family. Intermediate rate of deterioration was found in individuals having heterozygous alleles at qSL4, indicating an additive effect of the alleles. The assay can be used for fast, accurate, and reliable identification of deterioration rate after processing for salad.
Highlights
Lettuce (Lactuca sativa L.) is a popular vegetable predominantly grown for its leaves in moderate climates throughout the world[1]
The objectives of the present study were (i) to analyze quantitative trait locus (QTL)(s) for the rate of deterioration in additional biparental mapping population, (ii) to develop an marker-assisted selection (MAS) assay based on the molecular markers linked to qSL4, and (iii) to test the accuracy of this MAS assay in segregating families that originate from crosses between different horticultural types
The area under the deterioration progress steps (AUDePS) scores that show the rate of deterioration were approximately normally distributed in all experiments performed with the Pav × Par mapping population and seven F2 families
Summary
Lettuce (Lactuca sativa L.) is a popular vegetable predominantly grown for its leaves in moderate climates throughout the world[1]. To shorten the time needed for development of new cultivars, breeders could move from selection based on phenotype to selection based on genotype In this approach, molecular markers closely linked to the gene(s) of interest would be used to analyze DNA from a large number of individuals in the early stages of their development (or even seeds) without destroying the plants[17]. Molecular markers closely linked to the gene(s) of interest would be used to analyze DNA from a large number of individuals in the early stages of their development (or even seeds) without destroying the plants[17] Such molecular marker-assisted selection (MAS) can improve the accuracy and reduce the time needed for the identification of desirable genotypes. The utility of genomic selection was demonstrated for selecting slow deteriorating lettuce inbred lines from a bi-parental cross, results that have applicability to single seed descent programs but are not directly applicable to early generations[18]
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