Objective:
Objective 1: Develop physiological and biophysical approaches and tools to assess changes in plant germplasm viability and the potential causes during genebank preservation. Objective 2: Develop statistical genetic strategies and tools to sample and preserve plant genetic diversity in genebank collections and in situ reserves.

Approach:
The Preservation of Plant Genetic Diversity in Ex Situ Genebank program scientists conduct research to improve the biological and genetic integrity of genebanked germplasm and to standardize procedures for handling accessions and reporting associated data. 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 ¿ define tolerances to preservation stresses of selected propagules, ¿ develop methods to improve survival or reliably predict loss of viability over time, ¿ model the effects of mortality and regeneration on genetic composition, and ¿ develop sampling strategies for wild-collected germplasm that maximize genetic diversity while minimizing curator inputs for storage and regeneration. 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). PGPRU scientists and their collaborators will investigate major conceptual issues of repository biology and standardization using within-unit expertise in biophysics, plant physiology, cell and molecular biology and population genetics and National Plant Germplasm System (NPGS) curators¿ expertise on reproductive biology, phenotypic diversity, history and cultivation of their assigned collections. Our central position within NPGS allows us to develop protocols and predictive tools that are applicable to a wide variety of species and propagules.