ASSESSMENT OF GUAVA-DERIVED SSR MARKERS FOR THE MOLECULAR CHARACTERIZATION OF MYRTACEAE FROM DIFFERENT ECOSYSTEMS IN VENEZUELA

Abstract

Simple sequence repeat (SSR) markers have proven to be a very powerful tool to analyze genetic variability and relatedness at different hierarchical levels, for genetic map generation and validation as well as for many other applications. However, despite the fact that the development of species-specific SSR markers involves a laborious and costly task, there is also a lot of information concerning the successful use of SSR markers derived from one species and employed with other closely related taxa. In this research we report on the use of SSR developed for Psidium guajava, for the characterization of individuals belonging to the same genus and to the same family (Myrtaceae). The plant samples used in this work were collected in two Venezuelan sharply different and geographically isolated ecosystems. One of these ecosystems is a mountainous region in the Venezuelan Andes, in the state of Merida, and the other, is located south to the Orinoco River, situated in the state of Amazonas and characterized by typical rain forest vegetation. Both regions are ecosystems rich in Myrtaceae species, some of which are shared by both regions, whilst others are exclusive of one of these. Besides the morphological observations, an analysis with more than 16 pairs of guava-derived SSR primers was carried out. All primer combinations were assessed in terms of efficiency of amplification, number of loci, size of the amplification products, and degree of polymorphism. Due to the geographical distance between the sampled regions and our research lab, particularly those proceeding from Amazonas, and the low germination efficiency of most of the collected seeds, dry leaf sampled were used as a source of DNA. Successful amplifications of informative loci validate the transfer of most of the guava-derived SSR primers to other Myrtaceae species.