Isolation and Identification of Xylella fastidiosa that Cause Oleander Leaf Scorch

Abstract

During spring of 2022, leaf scorch symptom was observed in Nerium oleander plant in Erbil city. Surveys were carried out in three main Erbil streets (60-meter, 120 meter and Qasmlo) to determine the occurrence and distribution of oleander leaf scorch. Oleander leaf scorch (OLS) is a disease caused by xylem limited bacterium Xylella fastidiosa . The percentage of plants with Oleander leaf scorch infection ranged usually between 23-91%, and the disease was assessed the highest disease rate based on disease rating scale was recorded in 60-meter street is 91.95%, Qasmlo street is 89.07% and the lowest disease rate was observed in 120-meter street is 23.17%. In this study the bacterium was detected after isolated in laboratory as Gram stain test was performed and the isolated bacterium was Gram negative, rod shaped, non-flagellate and non-motile also identified by PCR were performed with two primers forward primer 16S (AGAG TTTG ATCC TGGC TCAG) and reverse primer 16S (GGCT ACCT TGTT ACGA CTT), amplified a 1200 bp fragment from the isolated OLS. The Analysis of BLAST revealed that the highest identity number query sequences were (100%) identified and submitted in GenBank and have taken accession number Xylella fastidiosa subsp. Sandyi (ON131099) and Xylella fastidiosa subsp. Sandyi (ON131100) also the phylogenetic results show the each identified bacteria are grouped in one clade with other sequences were stored in NCBI GenBank. This is a first report of a „ Xylella fastidiosa .in Erbil city.