New Disease Reports
New Disease Reports (2020) 41, 15. [http://dx.doi.org/10.5197/j.2044-0588.2020.041.015]
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First report of a 'Candidatus Phytoplasma asteris'-related strain associated with Melia azedarach phyllody in India

S. Tripathi, A. Verma, R. Verma*, S.S. Kushwah and G.K. Mahapatro

*rajverma0762@gmail.com

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Received: 17 Dec 2019; Published: 06 Feb 2020

Keywords: bead tree, chinaberry, Meliaceae, 16SrI

Chinaberry tree (Melia azedarach), also known as bead tree and belonging to the family Meliaceae, is an important ethnomedicinal tree with a wide natural distribution (Ntalli et al., 2010).  Its roots, stem and leaves possess various medicinal properties and have applications in various types of medicine.

Chinaberry trees showing phyllody-like symptoms and virescent flowers were observed in Narayangoan (Pune), Maharashtra, in April 2018. Samples of four plants with symptoms and four without symptoms (Figs. 1-2) were collected and tested to detect the presence of phytoplasmas and for further molecular characterisation. Total genomic DNA was isolated from petioles of both healthy and infected plants using a DNeasy Plant Mini Kit (Qiagen, Germany). PCR was performed using P1/P7 phytoplasma-specific universal primers followed by nested PCR with R16F2n/R16R2 primers (Deng & Hiruki, 1991; Schneider et al., 1995; Gundersen & Lee, 1996). Bands of the expected size (c. 1.8 and 1.2 kb, respectively) were obtained in samples from all symptom-bearing plants but not in the symptomless ones. The 16Sr DNA sequence amplified from a representative sample from a symptomatic plant was deposited in GenBank (Accession No. MN830223). Sequence comparison by BLAST analysis showed the highest sequence identity with members of the 16SrI phytoplasma group (aster yellows), such as Cocos nucifera lethal wilt phytoplasma (KY814724), Sandal spike phytoplasma (MK627541), Phyllanthus emblica witches' broom phytoplasma (MK627538), Sugarcane white leaf phytoplasma (MK627531) and Santalum album phytoplasma (MG865436). Phylogenetic analysis (Fig. 3) using the neighbour-joining method (MEGA X software) showed that the Melia azedarach phytoplasma sequence clustered within group 16SrI, subgroup B. Virtual RFLP analysis using iPhyClassifier (Zhao et al., 2009) further confirmed that the Melia azedarach phytoplasma sequence shares 99.8% identity with that of 'Candidatus Phytoplasma asteris' reference strain (M30790), and that the phytoplasma is a 'Candidatus Phytoplasma asteris'-related strain, belonging to the 16Sr group I, subgroup B.

To our knowledge, this is the first report of 'Candidatus Phytoplasma asteris' (16SrI-B) affecting M. azedarach in India. This finding holds significant importance for future epidemiological studies since M. azedarach could be an alternate host for phytoplasma (16SrI-B group) which infects several important vegetable crops cultivated in the country.

Figure1+
Figure 1: Infected plant of Melia azedarach showing phyllody-like symptoms and virescent flowers.
Figure 1: Infected plant of Melia azedarach showing phyllody-like symptoms and virescent flowers.
Figure2+
Figure 2: Healthy flowers and leaf of Melia azedarach.
Figure 2: Healthy flowers and leaf of Melia azedarach.
Figure3+
Figure 3: Phylogenetic analysis of Melia phytoplasma (MN830223) with other phytoplasma groups. Tree constructed using neighbour-joining method (Mega X software) and bootstrap values obtained for 1000 replicates. Diamond indicates Melia phytoplasma in the present study. Bar represents two substitutions in 100 positions.
Figure 3: Phylogenetic analysis of Melia phytoplasma (MN830223) with other phytoplasma groups. Tree constructed using neighbour-joining method (Mega X software) and bootstrap values obtained for 1000 replicates. Diamond indicates Melia phytoplasma in the present study. Bar represents two substitutions in 100 positions.

References

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  2. Gundersen DE, Lee IM, 1996. Ultrasensitive detection of phytoplasmas by nested-PCR assays using two universal primer sets. Phytopathologia Mediterranea 35, 144-151.
  3. Ntalli NG, Cottiglia F, Bueno CA, Alché LE, Leonti M, Vargiu S, Bifulco E, Menkissoglu-Spiroudi U, Caboni P, 2010. Cytotoxic tirucallane triterpenoids from Melia azedarach fruits. Molecules 15, 5866-5877. [http://dx.doi.org/10.3390/molecules15095866]
  4. Schneider B, Seemüller E, Smart CD, Kirkpatrick BC, 1995. Phylogenetic classification of plant pathogenic mycoplasma-like organisms or phytoplasmas. In: Razin S, Tully JG eds. Molecular and Diagnostic Procedures in Mycoplasmology. New York, USA: Academic Press, 369-380. [http://dx.doi.org/10.1016/B978-012583805-4/50040-6]
  5. Zhao Y, Wei W, Lee I-M, Shao J, Suo X, Davis RE, 2009. Construction of an interactive online phytoplasma classification tool, iPhyClassifier, and its application in analysis of the peach X-disease phytoplasma group (16SrIII). International Journal of Systematic and Evolutionary Microbiology 59, 2582-2593. [http://dx.doi.org/10.1099/ijs.0.010249-0]
To cite this report: Tripathi S, Verma A, Verma R, Kushwah SS, Mahapatro GK, 2020. First report of a 'Candidatus Phytoplasma asteris'-related strain associated with Melia azedarach phyllody in India. New Disease Reports 41, 15. [http://dx.doi.org/10.5197/j.2044-0588.2020.041.015]

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