Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic...Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic variation for shelf life in MAP,but their variation for nutrient retention is not known.Fifty accessions were evaluated for initial content of ascorbic acid (AsA),carotenoids,and sugars and their retention in storage.Accessions with high content and/or good retention of one or more nutrients were identified.The romaine accession ‘Floricos’ had high levels of all the three nutrients.Accessions with relatively high retention of all the three nutrients were ‘Salinas 88’,‘Siskiyou’,‘Solar’,SM09A,‘Romance’,and ‘Green Towers’.Romaine cultivars,‘Balady Barrage’,‘Green Towers’,and ‘Darkland’ had relatively high initial levels of all tested nutrients and good rate of their retention.There was no clear correlation between initial AsA/carotene concentrations and their retention rates,suggesting that besides content,retention of nutrients should also be a breeding target in a lettuce nutritional improvement program.Statistical analyses with the Pearson's correlation coefficient determined a negative relationship between tissue deterioration(AUDePS) and retention of all tested nutrients[r of-0.52 (P<0.0001) for AsA,-0.27 (P<0.01) for total carotene,and-0.59 (P<0.0001) for total sugars],suggesting that an increase in tissue deterioration intensifies nutrient decay.Broad-sense heritability (H^(2)) across the experiments was0.15 for AsA,0.23 for total carotene,and 0.50 for total sugars.Identification of germplasm with high nutrient content,extended shelf life and good nutrient retention provides valuable information for the lettuce industry and associated breeding programs.展开更多
Genetic diversity, population structure, and genome-wide marker-trait association analyses were conducted on a special collection of 298 homozygous lettuce(Lactuca sativa L.) lines. Each of these lines was derived fro...Genetic diversity, population structure, and genome-wide marker-trait association analyses were conducted on a special collection of 298 homozygous lettuce(Lactuca sativa L.) lines. Each of these lines was derived from a single plant that had been genotyped with 384 SNP markers using LSGermOPA. They included 122 butterhead, 53 romaine, 63 crisphead, 53 leaf and 7 stem types. Genetic diversity among these plants was assessed by pairwise comparison based on 322 high-quality SNP markers selected from 384 SNPs. Only 258 unique genotypes were identified among the 298 lines because 26 pairs or small groups(a total of 66 lines) shared identical genotypes. The average genetic similarity coefficient(GS) among these unique genotypes was 63.9% with a range of 40.6% to 99.8%. A phylogenetic tree was constructed based on the genotypic data. The most likely number of populations was estimated to be two or six. Association analysis between the 322 SNP markers and 10 phenotypic traits using the 258 homozygous lines was performed by three different methods: single factor analysis, general linear model analysis, and mixed linear model analysis. Nine significant marker-trait associations(SMTAs) were detected at P < 0.0001 with all three methods and also when considering kinship and/or population structure for this collection, with five SMTAs for seed coat color, one for leaf undulation, two for leaf anthocyanin, and one for stem anthocyanin. These markers will be useful in marker-assisted selection after further validation with segregating populations.展开更多
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 ...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.展开更多
基金supported by the Specialty Crop Block Grant Program of the U.S. Department of Agriculture's (USDA), Agricultural Marketing Service (AMS) through the California Department of Food and Agriculture (SCB15015)partly also by funding from the California Leafy Greens Research Board and by Oak Ridge Institute for Science and Education (ORISE) Research Participation Program。
文摘Fresh-cut lettuce is widely used in ready-to-eat salads sold in modified atmosphere packages (MAP).Even in MAP,fresh-cut lettuce has short shelf life that results in loss of nutrients.Lettuce cultivars exhibit genetic variation for shelf life in MAP,but their variation for nutrient retention is not known.Fifty accessions were evaluated for initial content of ascorbic acid (AsA),carotenoids,and sugars and their retention in storage.Accessions with high content and/or good retention of one or more nutrients were identified.The romaine accession ‘Floricos’ had high levels of all the three nutrients.Accessions with relatively high retention of all the three nutrients were ‘Salinas 88’,‘Siskiyou’,‘Solar’,SM09A,‘Romance’,and ‘Green Towers’.Romaine cultivars,‘Balady Barrage’,‘Green Towers’,and ‘Darkland’ had relatively high initial levels of all tested nutrients and good rate of their retention.There was no clear correlation between initial AsA/carotene concentrations and their retention rates,suggesting that besides content,retention of nutrients should also be a breeding target in a lettuce nutritional improvement program.Statistical analyses with the Pearson's correlation coefficient determined a negative relationship between tissue deterioration(AUDePS) and retention of all tested nutrients[r of-0.52 (P<0.0001) for AsA,-0.27 (P<0.01) for total carotene,and-0.59 (P<0.0001) for total sugars],suggesting that an increase in tissue deterioration intensifies nutrient decay.Broad-sense heritability (H^(2)) across the experiments was0.15 for AsA,0.23 for total carotene,and 0.50 for total sugars.Identification of germplasm with high nutrient content,extended shelf life and good nutrient retention provides valuable information for the lettuce industry and associated breeding programs.
基金funded by USDA-ARS CRIS Project 5438-21000026-00DNIFA multistate research project W006
文摘Genetic diversity, population structure, and genome-wide marker-trait association analyses were conducted on a special collection of 298 homozygous lettuce(Lactuca sativa L.) lines. Each of these lines was derived from a single plant that had been genotyped with 384 SNP markers using LSGermOPA. They included 122 butterhead, 53 romaine, 63 crisphead, 53 leaf and 7 stem types. Genetic diversity among these plants was assessed by pairwise comparison based on 322 high-quality SNP markers selected from 384 SNPs. Only 258 unique genotypes were identified among the 298 lines because 26 pairs or small groups(a total of 66 lines) shared identical genotypes. The average genetic similarity coefficient(GS) among these unique genotypes was 63.9% with a range of 40.6% to 99.8%. A phylogenetic tree was constructed based on the genotypic data. The most likely number of populations was estimated to be two or six. Association analysis between the 322 SNP markers and 10 phenotypic traits using the 258 homozygous lines was performed by three different methods: single factor analysis, general linear model analysis, and mixed linear model analysis. Nine significant marker-trait associations(SMTAs) were detected at P < 0.0001 with all three methods and also when considering kinship and/or population structure for this collection, with five SMTAs for seed coat color, one for leaf undulation, two for leaf anthocyanin, and one for stem anthocyanin. These markers will be useful in marker-assisted selection after further validation with segregating populations.
基金This work was partly supported by the California Leafy Greens Research Program and the United States Department of Agriculture,National Institute of Food and Agriculture,Specialty Crop Research Initiative program award#s 2010-51181-21631 and 2015-51181-24283.
文摘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.
