Genotyping and Molecular Identification of Date Palm Cultivars Using Inter-Simple Sequence Repeat (ISSR) Markers

Molecular markers are credible for the discrimination of genotypes and estimation of the extent of genetic diversity and relatedness in a set of genotypes. Inter-simple sequence repeat (ISSR) markers rapidly reveal high polymorphic fingerprints and have been used frequently to determine the genetic diversity among date palm cultivars. This chapter describes the application of ISSR markers for genotyping of date palm cultivars. The application involves extraction of genomic DNA from the target cultivars with reliable quality and quantity. Subsequently the extracted DNA serves as a template for amplification of genomic regions flanked by inverted simple sequence repeats using a single primer. The similarity of each pair of samples is measured by calculating the number of mono- and polymorphic bands revealed by gel electrophoresis. Matrices constructed for similarity and genetic distance are used to build a phylogenetic tree and cluster analysis, to determine the molecular relatedness of cultivars. The protocol describes 3 out of 9 tested primers consistently amplified 31 loci in 6 date palm cultivars, with 28 polymorphic loci.