Association of ‘Candidatus Phytoplasma asteris’ (16SrI group) with yellows of Achyranthes aspera in India

Abstract

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. 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 isolates using MEGA 4·0 tool showed close relationships with isolates of aster yellows ‘Ca. P. asteris’ (16SrI) group indicating the phytoplasma in A. aspera is an isolate of ‘Ca. P. asteris’. Achyranthes 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). Previously, ‘Ca. P. asteris’ has been reported in India on Cannabis sativa and Parthenium hysterophorus, but this is a first report of a ‘Ca. P. asteris’ associated with yellows on A. aspera worldwide.