Project Number: 5402-21000-011-03
Project Type: Specific C/A

Start Date: Jun 01, 2004
End Date: May 31, 2009

Objective:
Objectives: Using Secale as a test genus, 1) Determine whether phenotypic variability of quantitative traits changes after loss of seed viability during storage or after 3-4 rounds of seed increases. 2) Determine whether allelic frequencies of neutral markers and linkage relationships among neutral markers change during storage or after 3-4 rounds of seed increases. 3) Determine whether there are shifts in sequences of known regulatory genes during storage or after 3-4 rounds of seed increases. These data will be combined to determine the nature and extent to which phenotypic and genotypic traits change in rye during the seed storage and regeneration phases of ex situ genebanking. We will attempt to identify genes or loci that may be prone to nonrandom changes (selection) during genebanking and develop models to assess the risk of various mechanisms of genetic erosion.

Approach:
In this SCA we will make a detailed examination of genetic changes occurring in Secale (rye) accessions that are currently included in the NPGS or Polish germplasm system. Rye provides an ideal study system because there are many different accessions within existing collections that vary in their improvement status, mating systems and life history traits (inbred cultivars to weedy annuals) and that have undergone several rounds of seed regeneration. The large number of well-characterized and physically-mapped marker loci available from large scale genomic studies will allow high statistical power to infer changes during storage and regeneration cycles. In collaboration with the Polish NAS Botanical Garden and NPGS curators, we will identify ~20 accessions of rye that are in need of regeneration (to increase or reinvigorate seed) and can be used to compare genetic changes within accessions. To achieve a range of accession heterogeneity, we will select rye accessions at various stages of improvement from wild-collected materials, primitive landraces and self and open-pollinated types. Appropriate accessions will have 0.01, 0.02 and 0.03 suffixes to the NPGS identification, indicating regeneration cycle, and a documented regeneration protocol that also describes whether regenerations are sequential. Preferred accessions will have samples of the original accession and F1, F2, and F3 generations. Records will be reviewed for cohorts that have been maintained for different lengths of time. We plan to cross-check passport data to identify accessions that have been reintroduced to NPGS or Poland at different times (regenerated at different locations). If selected accessions have insufficient regeneration cycles, we will add another regeneration step. Once accessions are identified, experiments will be conducted to make inferences about the history of the accession (e.g., swings in population sizes, genetic bottlenecks or the magnitude of selection during storage and regeneration). We will determine whether 1) phenotypic variability of several quantitative traits within and among accessions change after seed storage or 3-4 rounds of seed increases and 2) allelic frequencies of neutral markers of both nuclear and cytoplasmic loci, and linkage relationships among neutral markers, change significantly after seed storage or 3-4 rounds of seed increases. The first objective will require evaluating plants for a series of quantitative traits including phenology and other fecundity-related traits that might be under selection during storage and regeneration. The second objective will require genotyping a subset of individuals from each population and regeneration cycle. These data will be combined to determine whether there are changes in frequencies among alleles at the various marker loci and changes in their genetic linkage relationships (i.e., linkage disequilibrium).

Project Team

Walters, Christina Richards, Christopher Jerzy Puchalski - Polish National Academy Of Sciences Botanical Gard 970-495-3202

Related National Programs

Plant, Microbial & Insect Genetic Res., Genomics, & Genetic Improv. I (301)   Plant Biological and Molecular Processes (302)