Detection of Spiroplasma citri from citrus trees in Turkey by molecular techniques

Abstract

Spiroplasma citri is the causal agent of Citrus Stubborn Disease (CSD) on cultivated citrus in the arid and semi-arid climate. Detection and characterization of this agent at the early stage of infection in citrus orchard and young citrus saplings in the nursery is of utmost importance to prevent the introduction and spread of the disease in Spiroplasma citri free areas. The current study was conducted in order to investigate the possible existence of different Spiroplasma citri strains in Turkey. Leaf and fruit samples were collected from ten years old citrus trees showing mostly short internodes, upright and mottled leaves, off-season blossoming and typical small and acorn-shaped fruits symptoms associated with citrus stubborn diseases in different villages of Kozan town of Adana province in Turkey. Polymerase chain reaction (PCR) was performed using Spiralin-f/r, P89-r/f and P58-6f/4r primer couples for the detection and characterization of the Turkish isolates. No positive sample was detected with the primers Spiralin-f/r. On the contrary, all samples reacted positively to the P89-r/f and P58-6f/4r primer couples. The obtained amplicon from the P89-r/f primers pair was sequenced and the phylogenetic tree was constructed. Phylogenetic tree showed that the Turkish Spiroplasma citri isolates are closely related to the Mexican, Spanish, Algerian, and Italian than those isolated from Morocco, Egypt and USA.