ABSTRACT
This study aimed to estimate the heritabilities of three economically important traits (total weight, shell shape and meat yield) in Australian blue mussels. The estimates were derived using a pedigree reconstructed from a suite of both published and newly developed microsatellite markers. A total of 135 microsatellite loci were tested, of which 10 loci produced consistent PCR amplification and reliable results across all samples (74 full-sibling families including 74 pairs of parents and 2536 offspring). Lack of polymorphism at the non-repetitive region of the adhesive protein gene confirmed that the broodstock were derived from a single species. A total of 1538 progenies (62.5%) could be assigned to single parent pairs, and the remainder were assigned to two families or more, so were discarded from further analysis. Heritabilities for total weight, shell shape and meat yield were low (0.051 ± 0.027, 0.085 ± 0.038 and 0.049 ± 0.028, respectively) but reflected large environmental variation rather than limited genetic variation, suggesting a family-based breeding programme could improve these traits. The genetic correlation between weight and meat yield, expressed as percentage of total mussel which was not shell, was negative, while the genetic correlation between meat yield and shell shape was weakly positive.
Subject(s)
Microsatellite Repeats/genetics , Mytilus/anatomy & histology , Mytilus/genetics , Pedigree , Animal Shells/anatomy & histology , Animals , Body Weight/genetics , Female , Inheritance Patterns , Male , Meat , Mytilus/growth & development , Statistics as TopicABSTRACT
A molecular marker-based map of perennial ryegrass (Lolium perenne L.) has been constructed through the use of polymorphisms associated with expressed sequence tags (ESTs). A pair-cross between genotypes from a North African ecotype and the cultivar Aurora was used to generate a two-way pseudo-testcross population. A selection of 157 cDNAs assigned to eight different functional categories associated with agronomically important biological processes was used to detect polymorphic EST-RFLP loci in the F(1)(NA(6) x AU(6)) population. A comprehensive set of EST-SSR markers was developed from the analysis of 14,767 unigenes, with 310 primer pairs showing efficient amplification and detecting 113 polymorphic loci. Two parental genetic maps were produced: the NA(6) genetic map contains 88 EST-RFLP and 71 EST-SSR loci with a total map length of 963 cM, while the AU(6) genetic map contains 67 EST-RFLP and 58 EST-SSR loci with a total map length of 757 cM. Bridging loci permitted the alignment of homologous chromosomes between the parental maps, and a sub-set of genomic DNA-derived SSRs was used to relate linkage groups to the perennial ryegrass reference map. Regions of segregation distortion were identified, in some instances in common with other perennial ryegrass maps. The EST-derived marker-based map provides the basis for in silico comparative genetic mapping, as well as the evaluation of co-location between QTLs and functionally associated genetic loci.
