The Detection and Density Fluctuation of Mulberry Dwarf Phytoplasma using Nested-PCR and Competitive-PCR Methods

• Published in: Journal of Korean Forestry Society Vol. 100; no. 4
• Main Authors: Chae, S.M., Chonbuk National University, Jeonju, Republic of Korea, Lee, S., Chonbuk National University, Jeonju, Republic of Korea, Cha, B.J., Chungbuk National University, Cheongju, Republic of Korea, Lee, H.I., National Plant Quarantine Service, Cheongju, Republic of Korea, Han, S.S., Chonbuk National University, Jeonju, Republic of Korea
• Format: Journal Article
• Language: Korean
• Published: 01.12.2011
• Subjects: Competitive PCR; FITOPLASMAS; mulberry dwarf; Nested-PCR; PHYTOPLASMAS; PHYTOPLASME
• ISSN: 0445-4650

The detectable levels and population fluctuations of phytoplasmas infecting dwarf mulberry trees were investigated using nested-PCR and competitive-PCR methods. Samples of five different types were studied : A. petiole of a leaf that displays dwarf symptoms, B. petiole from apparently healthy leaf residing on a branch also supports a leaf with dwarf symptoms, C. the branch portion that supports a leaf with dwarf symptoms, D. the leaf petiole from healthy appearing leaves on branch with no dwarf symptoms, and branch portion of branch with no dwarf symptoms, E. the rootlets of trees with dwarf symptoms. These 5-parts were collected from each tree during June - April, once in every two months. The phytoplasma was detected from all parts of collected mulberry samples during all seasons using nested-PCR with AS-1/AS-2 primer pairs. The phytoplasma was detected until 10⁴ dilution using direct-PCR method, but it was detected until 10∨13 dilution by the nested-PCR method. The density of pytoplasma was found to be 7.94×10∨18-10∨12 copies/μL in mulberry trees. The density of phytoplasma was observed throughout the year in all samples of mulberry trees. The highest rates of phytoplasma was found in the samples B and C during the early growing season followed by the sample A and D during the dormant season. Samples C and E displayed the highest phytoplasma density followed sample D. The density of phytoplasma appeared stable during all the seasons for samples C and A. The result of the present study demonstrates the utility of nested-PCR and competitive-PCR for detection and determination of population fluctuations of phytoplasmas in plant tissues.