Genetic variability in a representative 'Kerman' x 'Peters' population of pistachio (Pistacia vera L.) orchard

In 2013 there were approximately 250,000 acres of pistachios (Pistacia vera L.) grown in 22 counties throughout California. Many of these orchards are planted primarily with male P. vera ?Peters?, and female ?Kerman? trees. In recent years, growers have observed spatial and temporal variation in growth and fruiting density in these orchards. Field analyses of Fresno State?s pistachio orchard confirmed the presence of such phenotypic variations. These may be due to the prevailing environmental conditions, rootstock variability, or perhaps random mutagenesis that occurred during scion clonal propagation over the past 50 years. The objective of this study was to examine the latter possibility as the presence of superior/inferior ?Kerman? trees is not well documented. Total genomic DNA were isolated using either the CTAB method or QIAGEN DNeasy ? Plant Mini Kit and compared. The concentration and purity of isolated DNA products were analyzed using Nanodrop 2000 spectrophotometer. The method of Williams et al. (1990) was used for RAPD-PCR reactions with minor modifications. PCR products were stained with the novel nucleic acid stain GelRed. The advantages of the Kit over CTAB method were observed through the purity index ratio (A260/A280). The purity index ratio for DNA products isolated using either method were significant (P? 0.05). Three out of the seven RAPD primers that were screened revealed strong reproducible polymorphic fingerprints. A total of 72 scorable bands were produced, with an average of 24 bands per primer, of which 40 bands (53.7%) were polymorphic.