Journal of Phytology 2011, 3(8): 53-61 ISSN: 2075-6240 www.scholarjournals.org www.journal-phytology.com 53 Elucidation of Diversity among Psidium Species using Morphological and SPAR methods Abin Mani * , Rachana Mishra and George Thomas Allahabad Agriculture Institute –Deemed University, Allahabad, U.P., 211007, India C.S.R.D., People’s Group, Bhanpur, Bhopal, Madhya Pradesh, India, 462037 Article Info Summary Article History Molecular marker assisted characterization is lacking in Psidium genus. This study focuses on the genetic variability among eleven Psidium species by employing morphological and SPAR (RAPD and ISSR) methods. Morphological characterization was done based on parameters such as size, shape, foliage characters and habit of the plant specimens. In SPAR methods, 16 RAPD and 31 ISSR primers were used to distinguish the genetic variability. 3 RAPD and 4 ISSR primers showed 100% polymorphism, while average polymorphism in both marker systems was 77% and 81.6% respectively and the cluster analysis showed a more or less similar pattern. Dendrograms revealed two main clusters, separating the genus, F. sellowiana and Psidium sp. with a genetic distance of 0.86. Received : 19-06-2011 Revised : 01-08-2011 Accepted : 01-08-2011 *Corresponding Author Tel : 08982000810 Fax : 07554005226 Email: abinmani@gmail.com ©ScholarJournals, SSR Key Words: Psidium species, Morphological characterization, RAPD, ISSR. Introduction The genus Psidium belongs to the family Myrtaceae, which originated in tropical South America. Now it is naturalized in tropical and subtropical countries. In early 17 th century, Portuguese introduced guava to India (Menzel, 1985) which spreaded throughout the tropical and sub tropical Asian countries. It is believed that most of the guava introductions to India were first made at Basti in Uttar Pradesh (Prakash et al., 2002). The genus Psidium comprises approximately 150 species of small trees and shrubs in which only 20 species produce edible fruits and the rest are wild with inferior quality of fruits. Most commonly cultivated is the common guava, (Psidium guajava L.) and the other cultivated species include the Cattely guava or Strawberry guava (P. cattleianum Sabine), the Brazilian guava (P. guineense Sw.) and Costa Rician guava or Chinese guava (P. friedrichsthalianum Ndz.). The other species of Psidium are utilized for regulation of vigour, bearing programme, fruit quality improvement and resistance to pest and diseases (Morton, 1987). The chromosomal number of this genus is 2n = 22 (Nakasone and Paull, 1998) and all these species might share a common gene pool (Prakash et al., 2002). The SPAR (Single Primer Amplification Reaction) method offers a simple and economical means of genotype characterization. Many horticulturally important fruit crops including some guava varieties (Prakash et al., 2002; Dahiya et al., 2002; Rueda et al., 2006; Chen et al., 2007, Feria-Romero et al. 2009), its few species (Prakash et al., 2002; Sharma et al., 2007) and its related species Feijoa sellowiana (Dettori and Polambi, 2000) have been characterized using RAPD markers. The ISSRs help to identify closely related cultivars and to study evolutionary processes and phylogenetic studies (Prevost and Wilkinson, 1999; Raina et al., 2001). This marker system provides reproducible results that generate abundant polymorphism (Tsumura et al., 1996). Lot of confusion exists within Psidium species, as the different literatures arrange them in different order and the synonyms used in the nomenclature makes it more confusing, therefore, molecular marker assessed identification of duplicates in the germplasm is essential for the maintenance, commercialization and conservation of this genus. The plant genetic resource is one of the most valuable assets available to the mankind, their protection and conservation is of great importance for the future generation. This study focuses on assessing the genetic variability among the Psidium species and establishment of the genetic relationships between them. Material and Methods Morphological characterization of plant samples Two trees of each species, which received similar cultural treatments and matured trees, were selected for the field study and sample collection. Four uniform, healthy branches were tagged in all the four directions from each selected trees. The important parameters like height of the plant, mode of branching, stem form and shape; leaf arrangement, shape, size, colour and venation, the colour and morphology of the young shoots and leaves were compared within the samples as suggested by Melvilles (1960). Identification of the samples was done with the help of taxonomic literatures and herbarium and inter comparison was done within the samples, from different sites for clarification of species. The collected samples are listed in Table 1.