Location: Crop Improvement and Protection ResearchTitle: Molecular markers reliably predict post-harvest decay of fresh-cut lettuce in modified atmosphere packaging
|TRUCO, MARIA-JOSE - University Of California|
|MICHELMORE, RICHARD - University Of California|
|ANTONISE, RUDIE - Keygene Nv|
|MASSOUDI, MARK - Non ARS Employee|
Submitted to: Horticulture Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2018
Publication Date: 4/1/2018
Citation: Simko, I., Hayes, R.J., Truco, M., Michelmore, R.W., Antonise, R., Massoudi, M. 2018. Molecular markers reliably predict post-harvest decay of fresh-cut lettuce in modified atmosphere packaging. Horticulture Research. 5:21. https://doi.org/10.1038/s41438-018-0022-5.
Interpretive Summary: Lettuce leaves are mainly consumed raw as cut leaves in salads, but are also used in sandwiches and side dishes. Since lettuce is highly perishable, modified atmosphere packaging is designed to extend shelf-life while reducing the occurrence of wound-induced discoloration on cut surfaces. Even so, decay of lettuce pieces seen as darkening, water logging, and deterioration, may occur in MAP and make the product unmarketable. Genetic studies of two bi-parental populations derived from crossing parents with rapid and slow rate of decay showed that the decay is heritable trait (H2 of 0.56 – 0.87). The major genetic determinant of the decay rate in both populations was qSL4, the quantitative trait locus (QTL) located on linkage group 4. This QTL explained 40% to 74% of the total phenotypic variation of the trait in the two populations. We have developed a molecular-marker based assay to predict the rate of decay in fresh-cut lettuce. A combination of results obtained with molecular SNP markers with information about phenotypes of parents can be used to accurately predict the rate of decay in breeding lines, thus allowing selection of lines with superior shelf-life.
Technical 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 decay showed that the decay rate is heritable (broad spectrum heritability H2 of 0.56 – 0.87). The major genetic determinant of the decay rate in both populations was qSL4, the quantitative trait locus (QTL) located on linkage group 4. This QTL explained 40% to 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 group of 16 lettuce accessions with different rates of decay. Three of the haplotypes were always associated with very rapid rates of decay, while the other three haplotypes were associated with slow rates of decay. Two SNPs located 53bp apart were sufficient to separate 16 accessions into two groups with different rates of decay. 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 decay. Broad sense heritability (H2) of decay rate in seven families ranged from 0.64 to 0.90. The SNP-based assay accurately identified individuals with rapid, intermediate, and slow rates of decay in each family. Intermediate rate of decay 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 decay rate in lettuce genotypes after processing for salad.