46 Food, Agriculture & Environment, Vol.1 (3&4), August-December 2003 Detection of genetic diversity in Parkia timoriana (DC.) Merr. using randomly amplified polymorphic DNA analysis Robert Thangjam*, Damayanti Maibam and Jitendra G. Sharma Department of Life Sciences, Manipur University, Imphal – 795003, India. *Present address: Department of Botany, Modern College, Porompat Imphal – 795010, India. e-mail: robth@rediffmail.com, robert_thangjam@yahoo.com Received 19 January 2003, accepted 30 August 2003 Abstract Genetic variation of eight genotypes of tree beans grown in Manipur, India was investigated at the DNA level using randomly amplified polymorphic DNA (RAPD) analysis. Of the 12 random primers used 8 were analysed and a total of 95 bands scored. The percentage of polymorphism ranged from 0 to 57.14 with an average of 42.10 per primer. Pair-wise comparisons were made for the RAPD profiles obtained. Similarity measurement using UPGMA followed by cluster analysis resulted in 3 major groups. The results of the dendrogram and principal co-ordinate analysis were in considerable agreement with the overall representation of relationships among the genotypes studied. It was also observed that the similarities between genotypes from the different geographical locations revealed considerable discrimination. The results indicated that RAPD could be effectively used for genetic diversity analysis in the closely related accessions of a species as it is reliable, rapid and superior to those based on pedigree information. Key words: RAPD, Parkia timoriana, genetic diversity, Manipur. Introduction Among the numerous non-conventional foods used by the local communities in north-east India is a tree legume, popularly known as tree bean (locally ‘yongchak’ in Manipuri) or Parkia timoriana (DC.) Merr. [Syn. Parkia roxburghii G. Don.]. It grows commonly in the backyard of houses and forests throughout the states of north- east India. P. timoriana belongs to the family Leguminosae, sub- family Mimosoidae. The tree can thrive in different agro-climatic regions from colder hilly regions to the hotter plains. However, the problems associating with the taxonomy of Parkia are caused by the confusion of names, aggravated by cultivation, paucity of illustrations, and incomplete or missing types. Another problem is the pattern of variation in the characters of leaves, capitula and fruits 1 . Local people in Manipur generally believe that narrow and uniform pods having light green colour are superior in flavour than the others, and accordingly thirteen cultivars were identified based on their morphological characters 2 . Similarly, nine varieties of tree beans were reported from different tree bean growing belts in Manipur based on their palatability and other eating qualities 3 . P. timoriana is distributed from north-east India to Irian Jaya. This is the most widespread species of Parkia in the Indo-Pacific region, and the only one to occur on both sides of Wallace’s line 1 . Knowledge of the level, structure and origin of genetic variation within and between plant populations is important for the effective utilisation and conservation of species 4 . Factors determining the level and structure of genetic variation within plant species include evolutionary history characteristics, population density, mating system, and mechanisms of gene flow 5,6 . Although morphological characters and agronomic traits have been used traditionally to characterise levels and patterns of diversity, these traits alone represent only a small portion of the plant genome and are also influenced by environmental factors, thereby limiting their utility in describing the potentially complex genetic structures which may exist within and between taxa 7 . To overcome these constraints, various molecular approaches for the detection of variation have been devised in many crops including the techniques based on polymerase chain reaction (PCR) 8-10 . These ‘markers’ of genetic variation are generally independent of environmental factors and more numerous than phenotypic characters, thereby providing a clearer indication of the underlying variation in the genome of an organism 11 . At present the most popular of the DNA-based marker system is the PCR-based DNA technique referred to as RAPD (Randomly Amplified Polymorphic DNA) 9 . The present investigation attempts to study the genetic diversity in the representatives of eight genotypes of tree bean grown in different locations of Manipur using RAPD method. Materials and Methods The experiments were carried out with eight tree bean genotypes collected from different sites in Manipur (Table 1). The genotypes WFL Publisher Science and Technology www.world-food.net Food, Agriculture & Environment Vol.1(3&4) : 46-49. 2003 Table 1. Details of the different genotypes of P. timoriana grown in Manipur chosen for the study. Sl. no Genotypes Site District Longitude Latitude Elevation (metres above sea level) 1 Jiri I & II Jiribam Imphal East 93.12ºE 24.80ºN 40 2 Kangchup I & II Kangchup Senapati 93.81ºE 24.86ºN 820 3 Narankonjin I & II Narankonjin Imphal West 93.93ºE 24.73ºN 780 4 Kangpokpi I & II Kangpokpi Senapati 93.97ºE 25.15ºN 1270