48 / SEEDWORLD.COM JANUARY 2018 THE USDA-ARS National Plant Germplasm System (NPGS) contains a wealth of genetic diversity including improved varieties, breeding lines, lan- draces and crop wild relatives (CWR). Its hundreds of thousands of plant germ- plasm accessions have the potential to be a gold mine of genetic diversity for new, adapted varieties for food and fiber to feed the world’s growing population. “The NPGS is the largest distributor of plant genetic resources in the world,” says Patrick Byrne, Colorado State University professor of plant breeding and genetics. “Until breeders access the NPGS collection and use its genetic resources, the system is nothing more than a fancy morgue filled with dying potential for improved crops adapted to a changing climate.” Germplasm from the NPGS is freely available upon request without restric- tions for breeder use anywhere globally for plant breeding (assuming required import permits are provided). A Standard Material Transfer Agreement of the International Treaty on Plant Genetic Resources for Food and Agriculture, which specifies certain conditions of use, accompanies accessions distributed out- side the U.S. Germplasm is distributed as seeds, cuttings, dormant budwood, DNA, leaves, fruit, pollen, tubers, bulbs and in vitro cultures. Although about 250,000 accessions are distributed worldwide annually, a number of constraints limit the use of the system by plant breeders. Constraints on Increased Use Lack of accession information Often, little data about the original sampling site is available for individual accessions. Phenotypic data are typi- cally either of uneven quality or absent. The data that are available are often not relevant to breeding target traits, and have been recorded using many different descriptors. “Data on quantitative traits is espe- cially lacking,” Byrne says. “Many or most requesters of germplasm do not report back any evaluation data.” Technical constraints There may be limited fertility in interspecies crosses due to differences in ploidy level or other reproductive barriers. Recombination between chromosomes of wild and domes- ticated species is sometimes suppressed “Useful alleles may be hidden within an otherwise non-adapted background, leading to delayed maturity, disease sus- ceptibility or unacceptable fruit or seed characteristics,” says Gayle Volk, research plant physiologist, USDA-ARS Plant Germplasm Preservation Research, Fort Collins, Colorado. Germplasm Morgue or Gold Mine? The NPGS is the largest distributor of plant genetic resources in the world. Joe Funk jfunk@issuesink.com Making NPGS More Relevant Optimizing Collections Acquisition priorities for new germplasm must be balanced with multiple resource demands and maintenance and/or regeneration needs. Filling gaps may be constrained by political, logistical and economical factors. “Crop wild relatives are felt to be underrepresented for many crops, but bring special challenges,” says Byrne. “Stakeholder input, including from Crop Germplasm Committees, help guide acquisition priorities.” USDA sponsors several international explorations and exchanges every year. Phenotypic evaluation Arguably the most important challenge now in terms of time, cost, and complex- ity is to phenotype the collections. Continued development and imple- mentation of phenotyping technologies Some USDA funded projects have included large-scale phenotypic evaluation of NPGS collections.