African Journal of Biotechnology Vol. 10(8), pp. 1290-1298, 21 February, 2011 Available online at http://www.academicjournals.org/AJB ISSN 1684–5315 © 2011 Academic Journals Full Length Research Paper Genetic diversity of Myanmar rice and their implementation on management methods Shinsuke Yamanaka 1,6 , Shakeel Ahmad Jatoi 1,2 *, San-San-Yi 3 , Shankar L. Kothari 4 , Tin-Htut 5 and Kazuo N. Watanabe 1 1 Gene Research Center, Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan. 2 Plant Genetic Resources Program, National Agricultural Research Center, Park Road, Islamabad-45500, Pakistan. 3 Vegetables and Fruits Research and Development Center, Myanmar Agriculture Service, Ministry of Agriculture and Irrigation, Myanmar. 4 Department of Botany, University of Rajasthan, Jaipur 302 004, India. 5 Department of Agricultural Research, Yezin, Ministry of Agriculture and Irrigation, Myanmar. 6 National Institute of Biological Sciences, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan. Accepted 13 December, 2010 Myanmar has diverse agronomic landscape and potentially preserves high level of genetic resources for important crop species. However, little study on rice landrace diversity in Myanmar has been done. Genetic and phenotypic variation to characterize rice genetic resource in Myanmar was analyzed using molecular markers as well as common garden experiments. Two populations of rice landraces, a seed- bank population maintained by seed-propagation in a genebank for several generations and an “on- farm” population collected from agricultural lands were used. A functional (cytochrome P450 related PBA) and neutral (SSR) markers were used in this study. Phenotypic characteristics of representative agronomic traits in rice, such as culm length, panicle length, number of tillers and days to heading, were measured in both populations. Multivariate analysis suggested that the seed-bank and on-farm population had different genetic bases with both functional and neutral markers. There was no significant relationship between the functional and neutral markers based on Mantel test. In addition, PCA analyses of agronomic traits showed that a variation in the seed-bank population had narrower genetic bases than the on-farm population. Genetic bias caused by ‘unconscious selection’ during the genebank management processes may have occurred in the landraces. The importance of the conservation on on-farm landraces of Oryza sativa and its wild relatives was proposed in order to ensure the genetic resources for further breeding and conserve biological diversity. Key words: Oryza sativa, rice, landrace, on-farm, diversity, conservation. INTRODUCTION The union of Myanmar has diverse landscapes and con- tains continuous geographic variation from the delta area of the Ayeyarwaddy River in the southern region, to the mountainous areas in the northern region. This landscape diversity resulted in the diverse agricultural system for examples, deep water fields in the delta areas, irrigated *Corresponding author. E-mail: sajatoi@gmail.com. Tel : +92- 51-9255203. and rain-fed paddy fields in plain areas and slash and burn fields in the mountain areas. Geographic and crop diversity, coupled with diverse traditional agricultural sys- tems, contributes to the diversity of crop genetic resources in Myanmar (Garcia et al., 2003; San San Yi et al., 2008). However, the rice genetic resources of Myanmar have so far been unexploited in terms of their genetic relationships among different landraces (Garcia et al., 2003). Information based on systematic observations and evaluations of these resources is still very limited. Both cultivated rice and their wild relatives, play an important