Nested-PCR New Method for Detection of Phytoplasma Causing Big Bud Disease on Tomato in Iraq
Mesopotamia Journal of Agriculture,
symptoms similar to those produced by the phytoplasma disease "Big bud" were observed on tomatoes (Solanum lycopersicum L.) grown in the field in Mosul city, Iraq. Diseased plants were characterized by twisting, corrugated, yellowing or reddening of leaves. The sepals of the flowers acquired hypertrophied form, were fused together and created a bell-shaped sterile bud (phyllody) of green or anthocyanin color. The stems of the plants were lignified, and phloem necrosis was observed on the stem. In mid-September 2020, samples of 30 diseased and 2 healthy (control) tomato plants were collected from the fields. Phytoplasmas were detected by PCR and Nested-PCR in 10 diseased samples, use universal and specific primers. The results of a phylogenetic tree consisting of 27 genetic sequences of the 16 S ribosomal RNA gene of Candidatus Phytoplasma trifolii, locally isolated from Iraq/Mosul, showed a sequence identity with a high percentage of genetic similarity of 99% with Candidatus Phytoplasma trifolii 16Sr member VI-A. Clover proliferation group (16Sr VI), with various isolates from around the world.
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