Nuclear and Chloroplast Diversity of Rice (Oryza sativa L.) Germplasm from the Democratic People's Republic of Korea (DPRK; North Korea)

Rice accounts for 43% of staple food production in the Democratic People’s Republic of Korea (DPRK) today.  It is grown mostly in irrigated paddies on cooperative farms run by the government’s Public Distribution System and is affected by the short duration of the growing season, the harsh, cold winters and erratic distribution of rainfall, coupled with the unpredictable availability of fertilizer. Many of the existing rice varieties were released during 1966-1988 and have very similar genetic backgrounds due to the repeated use of a limited number of ancestral lines as parents in the breeding program. Reports from 1998 suggest that three varieties, Pyeongyang 15, Pyeongyang 18 and Pyeongyang 21, were cultivated on as much as 80% of rice land in the DPRK; however, little is known about the genetic or phenotypic variation of these or other varieties, nor about the identity or pedigrees of the varieties grown in the DPRK.  In this study, we analyzed genotypic and phenotypic variation among 80 O. sativa accessions collected in the DPRK by South Korean researchers during 1991-1995. Simple sequence repeat (SSR) and sequence-derived markers were used to evaluate genetic diversity in both the nuclear and chloroplast genomes and to examine the population structure of DPRK rice varieties. We also analyzed the relationship between subpopulation structure and phenotypic variation for traits related to seed morphology and cold tolerance.