|Research to Develop Strategies and Technologies for Preserving Genetic Diversity in ex situ Genebanks (PGPR)|
The PGPR team conducts research to improve the biological and genetic integrity of genebanked germplasm and to standardize procedures for handling accessions and reporting associated data. (Genebanking Strategies) Interrelated research goals will allow curators to preserve viability of conservation targets (Objective 1) and rationalize and validate the genetic diversity and integrity of those targets (Objective 2). Using taxa that are empirically-tractable systems, we will
A central theme is identifying appropriate conservation targets that capture desired genetic diversity, remain viable during storage and are available to the user when needed. A conservation target is a group of propagules (such as seeds or pollens) or an individual propagule (such as an explant) that comprises an accession valued for specific genes, genetic richness (number and frequency of alleles) or an allelic combination (genotype).
Need for Research
Plant genebanks are an important source of research materials supporting studies of crop improvement, new crops, ecology, evolutionary processes, conservation, systematics, plant metabolic processes, gene function and comparative genomics. A high degree of complexity is required to ensure the quality of genebanked samples, especially as researchers’ needs change and collections ever increase in size and age. The process of preservation imposes tremendous stress to cells. Capturing a broad range of diversity with differing responses to stress is a major genebanking goal, but the variation itself contributes to the problem of developing broadly applicable preservation protocols. Greater emphasis on wild-collected germplasm and specific genotypes of obligate out-crossing plants creates greater challenges to maintaining genetic richness and viability ex situ. One strategy is to ameliorate losses of germplasm during storage by preventing irreparable damage to propagules (Objective 1). Another strategy is to mitigate genetic erosion by managing collection size, diversity and conservation target (Objective 2).
Mortality during storage and its consequences to maintaining and expanding genetic diversity of small populations are significant impediments to efficient ex situ preservation. The ability to preserve diverse propagules within a species provides options for conserving genetic diversity within a collection and we plan to integrate developed technologies into multidimensional strategies that efficiently back up collections in long term storage. Some propagules are extremely sensitive to preservation stresses and the challenge is to develop effective storage protocols. Even with good storage protocols, viability declines rapidly after a threshold is reached and current viability monitoring procedures do not predict when this threshold will occur. Risks of genetic change through drift and selection increase with mortality, sample depletion and sample regeneration. Better operational standards are needed to flag samples for regeneration. Therefore, an integrated approach to the cyclical genebanking processes of sampling, preserving, regenerating, sampling, etc., is needed to ensure germplasm has high biological integrity and reliable genetic composition.
Viability and genetic diversity of species important to US landscapes and to human well being will be safely preserved in a consolidated facility and always available and replenishable. Genetic diversity will be comprehensive for species, but collections will be the appropriate size and contain the desired conservation targets. We will be able to evaluate propagule longevity upon receipt (before storage), eliminating the need to monitor viability and providing guidelines to schedule regenerations. Researchers will have a broad collection of quality-assured materials with good physical integrity and associated phenotypic, genotypic and ecological data.
Anticipated Products of the Research