تشخيص عوامل بيماري انگومك پسته با واكنش زنجيره اي پلي مراز PCR

DETECTION OF THE CAUSAL AGENTS OF PISTACHIO GUMMOSIS BY THE POLYMERASE CHAIN REACTION

Pistachio nut (Pistacia vera) is a major nut crop in Iran and gummosis is one of the crpʹs most serious diseases, diseased trees exuding gum from the crown and lower parts of the trunks of affected trees often die from root and crown rot. Several species of Phytophthora have been isolated from affected trees, but the principal causes of gummosis in Kerman province, the mjor pistachio-producing region in Iran, are two non-papillate species. To date one has been described as P. megasperma and the other as P. drechsleri based on their morphological and physiological factros. A technique based on the polymerase chain reaction (PCR) for the specific detection of the two main gummosis-causing Phytophthora species was developed using the nucleotide sequence of ITS1 and 1TS2 (internally transcribed spacer regions) of their genomic ribosomal RNA gene repeat (rDNA). DNA sequence from the ITS regions of the pistachio P. megasperma isolates were used to develop a pair of oligonucleotide primers, pisl fwd and pisl rev. These amplified a specific fragment within ITSI and ITS2 of the all 24 isolates of P. megasperma from pistachio. In further tests of specificity, the primers also generated an amplicon of the same size wiht DNA of Phytophthora sojae, P. melonis,