A Method for the Efficient Management and Utilization of Large Germplasm Collections

Abstract

To make effldent use of large germplasm collections, it is advisable to assemble a representative core collection and to evaluate the relationships among the traits studied. However, the assemblage of a core collection from very large germplasm collections is problematic. The computing resources needed to carry out genetic distance calculations and comparisons with commonly available programs is prohibitively large. The objects of this study were (i) to develop a method which assembles a core collection by maximizing the diversity (measured as mean Euclidean distance) from within groups of accessions defined by species, subspecies, and geographic origin and (ii) to test the effectiveness of the method on a collection of 20 997 annual Medicago accessions from the Australian Medicago Resource Center in Adelaide, South Australia, that had been evaluated for 27 agronomic characteristics. The method resulted in a core collection of 1705 accessions that represented 74% of the extremes of the 27 characters, indicating that the entire range of the characters was represented in most cases. Accessions representing the extremes easily could be added to the core collection. The method used requires relatively minor computing resources and should be useful to curators of large germplasm collections. To assess the relationships among the 27 measured traits, corrdation coefficients of all possible combinations of traits were calculated. The most strongly assodated traits were, as expected, such traits as grams of seed per plant and grams of pods per plant and indicated that some traits could be omitted from future evaluations with little loss of information, thereby increasing the efficiency with which germplasm evaluations can be carried ont.

Relationship of seed traits on initial progeny growth performance and divergence studies in Madhuca latifolia Macb. for further use in tree improvement

“…Of the 72 (36 genotypic and 36 phenotypic) correlations, 13 genotypic and seven phenotypic combinations were significant at 1% along with four genotypic and one phenotypic combinations was significant at 5% (Table 5). Skinner et al (1999) suggested only those correlation coefficients, which are greater than 0.70 or smaller than -0.70 as biologically meaningful so that 50% of the variation in one trait is predicted by the other. The seed trait pair showing such high correlation was 11 and all were positive.…”

The MedicagoFLOWERING LOCUS THomolog,MtFTa1, Is a Key Regulator of Flowering Time

“…Sequence variants within FT homologs from sunflower (Helianthus annuus; Blackman et al, 2010), wheat (Yan et al, 2006), rice (Hagiwara et al, 2009), and Arabidopsis (Schwartz et al, 2009) have been shown to be important for flowering-time adaptation. Since there is significant variation in flowering time in different Medicago accessions (Skinner et al, 1999), it is possible that variation in the activity or expression of the various Medicago FT family members underlies some of this variation.…”

Phenotypic diversity for morphological and agronomic traits in traditional Ethiopian highland maize accessions

“…However, only correlation coefficients greater than 0.71 or smaller than -0.71 have been suggested to be biologically important (Skinner et al, 1999), as more than 50% of the variation in one trait is predicted by the other (Snedecor & Cochran, 1980). In our study, we found such important associations (at genotypic level) between days to 50% tasseling and days to 50% silking (0.99), plant height and ear height (0.99), plant height and leaf length (0.97), ear diameter and 1000 seed weight (0.77), and number of rows per ear and number of kernels per row (0.95).…”