“Core-collection” Project in the National BioResource Project-Wheat, Japan: 2012 Progress report

Miyuki Nitta and Shuhei Nasuda

Laboratory of Plant Genetics, Graduate School of Agriculture, Kyoto University, Japan

Corresponding Author: Shuhei Nasuda

E-mail: nasushu@kais.kyoto-u.ac.jp

Key words: wheat, DNA marker, polymorphism, core-collection

The main aim of National Bioresources Project-Wheat (NBRP-Wheat) is to collect, store and supply wild species, landraces, and experimental strains of wheat and related species.  The registered plant materials we currently store are summed up to 13,000 accessions. Of them, 1,500 are genetic stocks mainly composed of aneuploids. The rest 11,000 are the wild species, landraces and historic cultivars. The collections of wild species and landraces derive from several expeditions since Dr. Kihara’s first expedition in 1955, and hardly can be collected at the sites today. These accessions have been widely used in evolutionary and diversity studies worldwide, which won high reputation by their sure taxonomic identification and the purity guaranteed by successive self-pollination. Although the data on collection site and pedigree are well documented at the Laboratory of Crop Evolution (the former Plant Germplasm Institute), Graduate School of Agriculture, Kyoto University, the genetic diversity and phenotypic variation are scarcely recorded. In the emerging genomics era, our stocks will be more important than before in search for valuable phenotypic traits. We are surely going to be able to evaluate and utilize the genetic diversity ex site conserved in the accessions. 

Establishment of a subset of the accessions that represent the total genetic diversity in the collection is desired, which is often referred as core-collection. A number of research papers have been published that deals with establishment of core-collections, large-scale genotyping, and finding marker-trait associations in wheat.

In the third term of NBRP-Wheat, we decided to establish core collections of hexaploid wheat including Triticum aestivum and exotic hexaploid wheat, tetraploid wheat (both wild and cultivated, AABB and AAGG species), and diploid wheat (T. monococcum, T. urartu, and T. boeoticum). Here we report the progress made in the fiscal year 2012.

Hexaploid wheat core-collection

We first planned to genotype whole collection of AABBDD species (about 3,500 accessions) by a DArT system. After consideration of seed propagation schedule, we decided not to genotype whole collection at a time, but instead extract DNA samples from around 200-400 plants annually propagated. The first version of core-collection, designated as NBRP-Wheat hexaploid wheat core-collection Ver. 1, was selected based on the collection location, taxonomic classification and importance in Japanese breeding program. The 190 accessions were already genotyped by SSR markers and their basic agronomic characters (20 phenotypes: anthocyanin pigmentation in coleoptile and cotyledon, growth habit, heading date, wax (leaf sheath), wax (spike), wax (column), flowering date, maturation date, number of effective tillers, plant height, spike length, column length, number of spikelet/spike, awnedness, spike color, grain color, glume hair, spike morphology, and 100 kernel weight) year 2011. We asked 12 domestic wheat researchers to test phenotype of their expertise. We obtained genotype data for 186 of 190 accessions based on the DNA microarray technology provided by DArT. The genotype data is analyzed and will be published elsewhere. We had a meeting on the core-collection on December 20th 2012 at Kyoto University to report the progress of core-collection project, and to discuss future plans.

Tetraploid wheat core-collection

We finished isolation of the DNA samples from 2,008 AABB species and 401 AAGG species. The collection site data of these lines are in our hands. We are adjusting the DNA concentration for the genotyping with small number of markers in DArT array format.

Diploid wheat core-collection

We finished DNA preparation for the 284 AA genome species.