Phytoplasma-associated Shoot Proliferation and Leaf Yellowing in Lettuce

Chung, Bong Nam; Kim, Jeong Soo; Cheong, Seung Ryong

doi:2007.23.3.151

Plant Pathol J > Volume 23(3); 2007 > Article

The Plant Pathology Journal 2007;23(3):151-154.
DOI: https://doi.org/10.5423/PPJ.2007.23.3.151 Published online September 30, 2007.

Phytoplasma-associated Shoot Proliferation and Leaf Yellowing in Lettuce

Bong Nam Chung, Jeong Soo Kim, Seung Ryong Cheong

Abstract

Phytoplasma was identified from leaf lettuce (Lactuca sativa) cultivated in commercial green-house in Korea. Diseased leaf lettuce revealed proliferation of shoots, and yellowing and shrinking of leaves (lettuce proliferation- K). Polymerase chain reaction (PCR) with universal primer pair P1/P6, and aster yellows (AY) specific primer pair R16F1/R1 amplified 1.5 kb and 1.1 kb length of DNA fragments, respectively. Nucleotide sequences of 16S rRNA gene were determined (Gen- Bank accession no EF489024). Phylogenetic analysis of 16S rDNA showed the closest relationship with AY phytoplasma (GenBank accession no. AY389822 and AY389826), indicating that lettuce proliferation-K is a member of AY. Phytoplasma bodies were detected in phloem sieve tubes of diseased lettuce by transmission electron microscopy. The structures had round or pleomorphic shapes with a diameter of 130-300 nm. Phylogenetic analysis of 16S rRNA gene, microscopic observation of phytoplasma bodies and symptomatology indicated that lettuce proliferation-K is caused by phytoplasma in the AY group. This is the first report of phytoplasma disease in lettuce in Korea.

Key Words: Lactuca sativa, phytoplasma, shoot proliferation, yellowing