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Kim, HyunJung,Jeong, Eung Gi,Ahn, Sang-Nag,Doyle, Jeffrey,Singh, Namrata,Greenberg, Anthony J,Won, Yong Jae,McCouch, Susan R Springer 2014 Rice Vol.7 No.-
<P><B>Background</B></P><P>Rice 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.</P><P><B>Results</B></P><P>We evaluated 80 <I>O. sativa</I> 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: <I>Group 1</I> corresponds to the <I>temperate japonica</I> subpopulation and represents 78.75% of the accessions, while <I>Group 2</I> shares recent ancestry with <I>indica</I> varieties. Interestingly, members of <I>Group 1</I> are less diverse than <I>Group 2</I> at the nuclear level, but are more diverse at the chloroplast level. All <I>Group 2</I> varieties share a single <I>Japonica</I> maternal-haplotype, while <I>Group 1</I> varieties trace maternal ancestry to both <I>Japonica</I> and <I>Indica</I>. Phenotypically, members of <I>Group 1</I> have shorter grains than <I>Group 2,</I> and varieties from breeding programs have thicker and wider grains than landraces. Improved varieties in <I>Group</I> 1 also show similar and/or better levels of cold tolerance for most traits, except for <I>spikelet number per panicle</I>. 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.</P><P><B>Conclusions</B></P><P>Diversity 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.</P>