Seedling selection identifies superior seedlings as candidate cultivars based on predicted genetic potential for traits of interest.Traditionally,genetic potential is determined by phenotypic evaluation.With the avail...Seedling selection identifies superior seedlings as candidate cultivars based on predicted genetic potential for traits of interest.Traditionally,genetic potential is determined by phenotypic evaluation.With the availability of DNA tests for some agronomically important traits,breeders have the opportunity to include DNA information in their seedling selection operations—known as marker-assisted seedling selection.A major challenge in deploying marker-assisted seedling selection in clonally propagated crops is a lack of knowledge in genetic gain achievable from alternative strategies.Existing models based on additive effects considering seed-propagated crops are not directly relevant for seedling selection of clonally propagated crops,as clonal propagation captures all genetic effects,not just additive.This study modeled genetic gain from traditional and various marker-based seedling selection strategies on a single trait basis through analytical derivation and stochastic simulation,based on a generalized seedling selection scheme of clonally propagated crops.Various trait-test scenarios with a range of broad-sense heritability and proportion of genotypic variance explained by DNA markers were simulated for two populations with different segregation patterns.Both derived and simulated results indicated that marker-based strategies tended to achieve higher genetic gain than phenotypic seedling selection for a trait where the proportion of genotypic variance explained by marker information was greater than the broad-sense heritability.Results from this study provides guidance in optimizing genetic gain from seedling selection for single traits where DNA tests providing marker information are available.展开更多
Auxin has been suggested to play an essential role in regulating apple fruit maturation and ripening, though the molecular function of auxin and its interaction with ethylene during apple fruit development are largely...Auxin has been suggested to play an essential role in regulating apple fruit maturation and ripening, though the molecular function of auxin and its interaction with ethylene during apple fruit development are largely unknown. To understand the function of auxin during apple fruit maturation and ripening, auxin efflux carrier and IAA-amido synthetase encoding genes were identified from the apple genome based on the results of previous microarray analysis. The expression patterns of these genes were analyzed using qRT-PCR during 10 - 12 weeks of fruit maturation for two apple cultivars: “Golden Delicious” (GD) and “Cripps Pink” (CP), which have the distinct patterns of maturation progression. Our results showed that the expressions of auxin efflux carrier and IAA-amido synthetase genes have a correlation with the timing of ethylene biosynthesis pathway activation in both cultivars. The earlier and stronger expression of MdGH3.102 and MdAECFP1 in the fruit of GD, a mid-season cultivar, correlates with the earlier activation of a pre-climacteric ethylene biosynthesis gene of MdACS3, compared with that in CP, a late-ripening apple cultivar. Results of exogenous IAA treatment indicated that the expression patterns of the genes were regulated in a fruit maturity dependent manner. Our results suggested that the dynamics of the auxin level in apple fruit cortex could be one of the key factors influencing the timing of ethylene biosynthesis pathway activation and consequently contributed to the control of the apple maturation progression.展开更多
基金This work was funded by USDA’s National Institute of Food and Agriculture-Specialty Crop Research Initiative project,‘RosBREED:Enabling Marker-Assisted Breeding in Rosaceae’(2009-51181-05808)‘Tree Fruit GDR:Translating Genomics into Advances in Horticulture’(2009-51181-06036)+2 种基金‘RosBREED:Combining Disease Resistance and Horticultural Quality in New Rosaceous Cultivars’(2014-51181-22378)‘GDR:Empowering Specialty Crop Research through Big-Data Driven Discovery and Application in Breeding’(2014-51181-223760)USDA Hatch funds provided to the Department of Horticulture,Washington State University.
文摘Seedling selection identifies superior seedlings as candidate cultivars based on predicted genetic potential for traits of interest.Traditionally,genetic potential is determined by phenotypic evaluation.With the availability of DNA tests for some agronomically important traits,breeders have the opportunity to include DNA information in their seedling selection operations—known as marker-assisted seedling selection.A major challenge in deploying marker-assisted seedling selection in clonally propagated crops is a lack of knowledge in genetic gain achievable from alternative strategies.Existing models based on additive effects considering seed-propagated crops are not directly relevant for seedling selection of clonally propagated crops,as clonal propagation captures all genetic effects,not just additive.This study modeled genetic gain from traditional and various marker-based seedling selection strategies on a single trait basis through analytical derivation and stochastic simulation,based on a generalized seedling selection scheme of clonally propagated crops.Various trait-test scenarios with a range of broad-sense heritability and proportion of genotypic variance explained by DNA markers were simulated for two populations with different segregation patterns.Both derived and simulated results indicated that marker-based strategies tended to achieve higher genetic gain than phenotypic seedling selection for a trait where the proportion of genotypic variance explained by marker information was greater than the broad-sense heritability.Results from this study provides guidance in optimizing genetic gain from seedling selection for single traits where DNA tests providing marker information are available.
文摘Auxin has been suggested to play an essential role in regulating apple fruit maturation and ripening, though the molecular function of auxin and its interaction with ethylene during apple fruit development are largely unknown. To understand the function of auxin during apple fruit maturation and ripening, auxin efflux carrier and IAA-amido synthetase encoding genes were identified from the apple genome based on the results of previous microarray analysis. The expression patterns of these genes were analyzed using qRT-PCR during 10 - 12 weeks of fruit maturation for two apple cultivars: “Golden Delicious” (GD) and “Cripps Pink” (CP), which have the distinct patterns of maturation progression. Our results showed that the expressions of auxin efflux carrier and IAA-amido synthetase genes have a correlation with the timing of ethylene biosynthesis pathway activation in both cultivars. The earlier and stronger expression of MdGH3.102 and MdAECFP1 in the fruit of GD, a mid-season cultivar, correlates with the earlier activation of a pre-climacteric ethylene biosynthesis gene of MdACS3, compared with that in CP, a late-ripening apple cultivar. Results of exogenous IAA treatment indicated that the expression patterns of the genes were regulated in a fruit maturity dependent manner. Our results suggested that the dynamics of the auxin level in apple fruit cortex could be one of the key factors influencing the timing of ethylene biosynthesis pathway activation and consequently contributed to the control of the apple maturation progression.
