New Disease Reports
New Disease Reports (2008) 18, 12.
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Association of ‘Candidatus Phytoplasma asteris’ (16SrI group) with yellows of Achyranthes aspera in India

S.K. Raj*, S. K. Snehi, S. Kumar, D. Pratap and M.S. Khan

*skraj2@rediffmail.com

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Accepted: 19 Sep 2008

Achyranthes aspera (family Amaranthaceae), commonly known as "Latjeera", is an annual herb that grows wild throughout India. It is an indigenous medicinal plant of Asia and is commonly used by traditional healers for the treatment of malarial fever, dysentery, asthma, hypertension and diabetes (Girach & Khan, 1992). A root extract is also used to treat scorpion and snake bites by Indian tribes. A yellows disease was noticed on a number of A. aspera plants growing as weeds beside a road between Sitapur and Lucknow, U. P., India during February, 2008. The diseased plants showed typical yellows and small leaves symptoms as compared to healthy ones (Fig. 1).

Samples from plants with symptoms were collected and total DNA was extracted from ~100 mg of leaf tissues employing a phytoplasma enrichment procedure (Ahrens & Seemüller, 1992). Amplicons of ~1.5 kb and ~1.2 kb were produced respectively by direct polymerase chain reaction (PCR) using primers P1/P6 (Deng & Hiruki 1991) followed by nested PCR using 1:10 diluted first stage products and primers R16F2n/R16R2 (Gundersen & Lee 1996). Three amplicons of ~1.2 kb were sequenced and consensus sequence data deposited in GenBank (Accession No. EU573926). BLAST search analysis showed 99% sequence similarities with the members of ‘Candidatus phytoplasma asteris’ (16SrI group phytoplasma): sugarcane yellows (EU423900); periwinkle little leaf (EU375834, DQ381535); onion yellows (AP006628, D12569); carrot phytoplasma (EU215426, EU215425) and aster yellows phytoplasma (EF489024, AY665676). Phylogenetic analysis of the phytoplasma isolate using MEGA 4.0 tool showed close relationships with isolates of aster yellows ‘Ca. P. asteris’ (16SrI) group (Fig 2). Therefore, the phytoplasma in A. aspera has been identified as an isolate of ‘Ca. P. asteris’.

A. aspera has been reported as a host of witches'-broom disease of lime caused by ‘Candidatus Phytoplasma aurantifolia’ in the Sultanate of Oman (Moghal et al, 1998). ‘Ca. P. asteris’ has been reported in India on Cannabis sativa and Parthenium hysterophorus, but to our knowledge this is a first report of a ‘Ca. P. asteris’ associated with yellows on A. aspera anywhere in the world including India.

Figure1+
Figure 1: Yellows and small leaves symptoms on naturally infected A. aspera (left) as compared with healthy plant (right).
Figure 1: Yellows and small leaves symptoms on naturally infected A. aspera (left) as compared with healthy plant (right).
Figure2+
Figure 2: Phylogenetic analysis of the phytoplasma isolate of A. aspera: EU573926 (highlighted by grey) using sequences of phytoplasma isolates of various groups available in GenBank database. Phylogenetic tree (generated by MEGA 4.0 tool with 100 bootstrap values) showing close relationships of A. aspera phytoplasma with isolates of aster yellows ‘Ca. P. asteris’ (16SrI group phytoplasma).
Figure 2: Phylogenetic analysis of the phytoplasma isolate of A. aspera: EU573926 (highlighted by grey) using sequences of phytoplasma isolates of various groups available in GenBank database. Phylogenetic tree (generated by MEGA 4.0 tool with 100 bootstrap values) showing close relationships of A. aspera phytoplasma with isolates of aster yellows ‘Ca. P. asteris’ (16SrI group phytoplasma).

References

  1. Ahrens U, Seemüller E, 1992. Detection of DNA of plant pathogenic mycoplasma-like organism by a polymerase chain reaction that amplifies a sequence of the 16S rRNA gene. Phytopathology 82, 828-32.
  2. Deng S, Hiruki C, 1991. Amplification of 16S rRNA genes from culturable and nonculturable mollicutes. Journal of Microbiological Methods 14, 53-61.
  3. Girach RD, Khan ASA, 1992. Ethananomedicinal uses of Achyranthes apera leaves in Orissa (India). International Journal of Pharmacognosy 30, 113-115.
  4. Gundersen DE, Lee IM, 1996. Ultrasensitive detection of phytoplasmas by nested-PCR assays using two universal primer pairs. Phytopathologia Mediterranea 35, 144-151.
  5. Moghal SM, Zidgali AD, Moustafa SS, 1998. Natural host range and reactions of citrus species to witches' broom disease of lime (WBDL) in Oman. In: Proceedings of the IPM Conference, Sultan Qaboos University, Muscat, pp 143-152.
This report was formally published in Plant Pathology

©2008 The Authors