First Report of Association of ‘Candidatus Phytoplasma asteris’ with Moringa oleifera Leaf Yellowing and Stunting Disease in India
- S. K. Singh1
- K. Vemana2
- M. Gurivi Reddy3
- K. Rawat4
- N. K. Sharma5
- J. K. Yadav6
- G. P. Rao4 †
- 1Department of Plant Pathology, Acharya Narendra Dev University of Agriculture & Technology, Kumarganj 224229, Uttar Pradesh, India
- 2Agricultural Research Station, Acharya NG Ranga Agricultural University, Andhra Pradesh, Kadiri 515591, India
- 3Department of Plant Pathology, Sri Venkateswara Agricultural College, Acharya N. G. Ranga Agricultural University, Tirupati 517502, Andhra Pradesh, India
- 4Division of Plant Pathology, ICAR-Indian Agricultural Research Institute, New Delhi 1100012, India
- 5ICAR-Krishi Vigyan Kendra, Kaushambi, Uttar Pradesh, India
- 6ICAR-Krishi Vigyan Kendra, Unnao, Uttar Pradesh, India
Moringa oleifera (family Moringaceae), also known as the “drumstick tree,” is a significant nutritious and medicinal plant that is commonly grown in India and contains a variety of vital phytochemicals. M. oleifera is used in several Indian herbal medicine formulations to treat a variety of illnesses (Kumar and Rao 2021). Typical phytoplasma symptoms of leaf yellowing and stunting were observed in M. oleifera trees at up to 10% incidence at Acharya Narendra Dev University of Agriculture & Technology, Ayodhya, Uttar Pradesh, India, in November 2021 and stunting with reduced fruit bearing symptoms with 8% incidence in October 2021 at Jonnalakothapalle village of Mudigubba mandal of Ananthapuramu district in Andhra Pradesh, India. To investigate the possibility of a phytoplasma association with the symptoms, total DNA was isolated from the leaf samples collected from two diseased and two healthy plants from both the locations using the CTAB method. The isolated DNA was analyzed by nested polymerase chain reaction (PCR) with universal phytoplasma primer pairs P1/P7 and R16F2n/R16R2 for the 16S rRNA gene (Deng and Hiruki 1991; Gundersen and Lee 1996) and secAfor1/sArev3 and SecAfor2/ SecArev3 for the secA gene (Hodgetts et al. 2008). Amplicons of the expected size (∼1.25 kb from 16S rRNA gene and ∼480 bp from secA gene) were obtained from symptomatic plants only. The nested PCR products were cloned (pGEM-T Easy Vector, Promega) and sequenced (ABA Biotech, India), and the sequences were deposited in GenBank with accession numbers OP358449, OP358450, OP358451, and OP358452 for the 16SrRNA gene (∼1.25 kb) and OP358443, OP358444, OP358445, and OP358446 for the secA gene (∼480 bp). BLASTn analysis revealed that the partial 16S rRNA gene sequences of M. oleifera phytoplasma isolate shared up to 99.9% sequence identity with the strain ‘Candidatus Phytoplasma asteris’ (accession nos. MN909051 and MN909047), and secA gene sequences shared up to 100% sequence identity with ‘Ca. P. asteris’ (accession nos. KJ434315 and KJ462009) belonging to 16SrI group. The 16S rRNA and secA genes sequence-based phylogenetic analysis showed that the phytoplasma strain associated with M. oleifera leaf yellowing and stunting clustered within the 16SrI phytoplasma group closest to 16SrI-B (‘Ca. P. asteris՚) subgroup strains. Furthermore, the virtual restriction fragment length polymorphism pattern derived from the query 16S rDNA F2nR2 fragment is identical (similarity coefficient 1.00) to the reference pattern of 16Sr group I, subgroup B (GenBank accession AP006628). To the best of our knowledge, this is the first report of the 16SrI-B subgroup of the phytoplasma strains with M. oleifera in the world. ‘Ca. P. asteris’ (16SrI-B subgroup) strains have been reported from several other commercial crops and weed hosts in India, and efficient leafhopper vectors have been identified (Rao 2021; Reddy et al. 2021). This indicates that the ‘Ca. P. asteris’-related strains (16SrI-B) are widespread and infecting several plant species in India. The increasing incidence of the 16SrI-B strain and its wide host range in India strongly suggest further research into the epidemiology involved in the dynamic spread of the disease in order to recommend a suitable management approach.
The author(s) declare no conflict of interest.
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