Nuclear and chloroplast diversity and phenotypic distribution of rice (Oryza sativa L.) germplasm from the democratic people's republic of Korea (DPRK; North Korea).

Yong Jae Won,Namrata Singh,Jeffrey Doyle,Sang-Nag Ahn,Eung Gi Jeong,Hyunjung Kim,Susan R Mccouch,Anthony J Greenberg

doi:10.1186/s12284-014-0007-4

Abstract

BackgroundRice accounts for 43% of staple food production in the Democratic People’s Republic of Korea (DPRK). The most widely planted rice varieties were developed from a limited number of ancestral lines that were repeatedly used as parents in breeding programs. However, detailed pedigrees are not publicly available and little is known about the genetic, phenotypic, and geographical variation of DPRK varieties.ResultsWe evaluated 80 O. sativa accessions from the DPRK, consisting of 67 improved varieties and 13 landraces. Based on nuclear SSR analysis, we divide the varieties into two genetic groups: Group 1 corresponds to the temperate japonica subpopulation and represents 78.75% of the accessions, while Group 2 shares recent ancestry with indica varieties. Interestingly, members of Group 1 are less diverse than Group 2 at the nuclear level, but are more diverse at the chloroplast level. All Group 2 varieties share a single Japonica maternal-haplotype, while Group 1 varieties trace maternal ancestry to both Japonica and Indica. Phenotypically, members of Group 1 have shorter grains than Group 2, and varieties from breeding programs have thicker and wider grains than landraces. Improved varieties in Group 1 also show similar and/or better levels of cold tolerance for most traits, except for spikelet number per panicle. Finally, geographic analysis demonstrates that the majority of genetic variation is located within regions that have the most intensive rice cultivation, including the Western territories near the capital city Pyungyang. This is consistent with the conscious and highly centralized role of human selection in determining local dispersion patterns of rice in the DPRK.ConclusionsDiversity studies of DPRK rice germplasm revealed two genetic groups. The most widely planted group has a narrow genetic base and would benefit from the introduction of new genetic variation from cold tolerant landraces, wild accessions, and/or cultivated gene pools to enhance yield potential and performance.

Highlights

Rice accounts for 43% of staple food production in the Democratic People’s Republic of Korea (DPRK)
Population structure in DPRK germplasm When 80 DPRK accessions (Figure 1, Additional file 1: Table S1) were evaluated using population structure analysis method based on 51 nuclear SSR loci, best fit was observed when the population was divided into two groups, K = 2 (Additional file 2: Figure S1A)
Among the three known varieties widely cultivated in DPRK, Pyeongyang 15 belonged to Group 1 while two other varieties, Pyeongyang 18 and Pyeongyang 21 belonged to Group 2

Summary

Introduction

Rice accounts for 43% of staple food production in the Democratic People’s Republic of Korea (DPRK). Unlike other major staple cereals, humans consume most rice directly as a whole grain, and only a small percentage (~7%) of rice is exported across sociopolitical borders (FAO 2012) This consumption pattern has profound consequences for the eco-regional forms of adaptation found within rice cultivars and drives the selection of locally preferred grain quality characteristics (Fitzgerald et al 2009). Within this manuscript, we focus on genetic and phenotypic variation found in rice from the Democratic People’s Republic of Korea (DPRK: North Korea). Knowledge of the genetic variability within rice from the DPRK could potentially benefit the serious food security issues that many of its citizens face

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