Effort towards a world pea (Pisum sativum L.) germplasm core collection: The case for common markers and data compatibility.

Interpretive Summary: It is widely recognized that the genetic diversity of cultivated plants has narrowed as a result of thousands of years of domestication and associated bottlenecks. To avoid a permanent loss of diversity, conservation of plant genetic resources in the form of ex situ collections was pioneered by N.I.Vavilov (1926). In the case of pea (Pisum), the genus on which modern genetics was founded, several large germplasm collections are maintained worldwide. There are many benefits resulting from the exploitation of older varieties, landraces and even wild crop relatives, for breeding new varieties to cope with environmental and demographic changes. Consequently, within the last two decades, the study of genetic diversity for both germplasm management and breeding has received much attention. In order to facilitate Pisum sp. germplasm management and increased efficiency of use, a core collection is being developed under the concept proposed by Frankel and Brown (1984). Also for breeding it is important to know the genetic basis of cultivars, especially whether they have become too narrow in diversity to render crops more vulnerable to diseases or pests. Potentially accessions most genetically distinct from others are likely to contain the greatest number of novel alleles, which can be exploited in breeding.Technical Abstract: Using SSR and RBIP markers, several major world pea germplasm collections have been analyzed and core collections formed. These include over 1,200 pea accessions of Chinese origin contained within a larger set of over 2,000 accessions analyzed by 21 SSR loci , 310 of 5,394 USDA pea germplasm accessions have been assessed by 37 RAPD and 15 SSR markers, INRA France used an extensive set of 121 protein and SSR markers to genotype 148 INRA accessions , The CDC Canada pea collection (~100 accessions) was studied by RAPD, ISSR and SSR, the entire JIC pea germplasm (~ 3,500 accessions), comprised largely of expedition collections, was analyzed using 45 RBIP markers and over 1,400 pea accessions held at the Czech National Pea Germplasm collection were genotyped using a combination of RBIP and SSRs. With advances in model legume sequencing and increased genomic knowledge, there has been a switch to gene-based markers in pea. This trend can be expected to further proliferate in line with rapid advances in high throughput single-nucleotide polymorphism (SNP) generation and detection assays, such as next generation sequencing technologies. These provide powerful platforms with the potential for the rapid characterization of the genomes of thousands of diverse pea genotypes. Pisum ranks fourth among the world’s most important grain legumes yet is not a mandate crop within the CGIAR system. Our next objective is to combine of available data sets into a virtual global collection and the development of a dispersed international reference collection. The establishment of a virtual pea world reference collection, combining suitable molecular platforms with robust morphological parameters to address population structure, will allow for cross-comparison of ex situ pea germplasm and G x E studies of agronomic traits