A new disease of Trachyspermum ammi, commonly known as Ajwain in India, was observed in Lucknow, ... more A new disease of Trachyspermum ammi, commonly known as Ajwain in India, was observed in Lucknow, India. The symptoms included small chlorotic leaves, highly proliferating shoots, witches’ broom appearance, shortened internodes and an overall stunted growth. Poor flower heads and fruit setting caused considerable yield losses for farmers. In transmission electron microscopy, pleomorphic bodies were detected in the phloem cells of diseased plants but not in those of healthy plants. The disease etiology was investigated using direct and nested polymerase chain reaction with phytoplasma-specific primers, DNA sequencing, and phylogenetic analysis. Phylogenetic analysis indicated that this phytoplasma clustered in the 16SrVI group. A 1,249 bp sequence (FJ970035) of the 16S rRNA gene from the phytoplasma showed 99% homology with the 16S rRNA gene, (FJ427295) of Ca. Phytoplasma trifolii strain A6 belonging to the phytoplasma group VI (reported from Iran). This is the first report of phytoplasma infection affecting Ajwain (T. ammi).
Alterations in essential oil gland number, distribution and fine structure, and the oil content i... more Alterations in essential oil gland number, distribution and fine structure, and the oil content in the leaf of Mentha arvensis L. were examined during its growth and senescence. Accumulation of essential oil occurred predominantly during the rapid leaf expansion phase followed by a similar decline. The oil gland (trichome) number increased upto leaf maturation and declined thereafter. Initially, cuticle remains tightly apposed to the secretory head of oil glands but progressively a sub-cuticular space appears to be created for the oil. Considerable enlargement of vacuole with ageing is witnessed, whereas cytoplasm gradually decreases to a thin peripheral layer. Some secretory cells from senescing leaf were found almost empty, having only a few remnant oil droplets.
Archives of Phytopathology and Plant Protection, 2011
A new severe little leaf disease was observed on P. grandiflora, popular as Moss-rose Purslane, w... more A new severe little leaf disease was observed on P. grandiflora, popular as Moss-rose Purslane, widely grown in temperate zones. Characteristic symptoms, ultrastructural studies, antibiotic response and amplification of 16S ribosomal DNA fragments (about 1.5 kb) by polymerase chain reaction (PCR) from infected samples, suspect the involvement of phytoplasma as a pathogen. Nested PCR product, 1.2 kb, with primer pairs R16F2n/R16R2 used for cloning and sequencing. Comparision of the 16S rRNA gene sequences showed that the causal, PLL phytoplasma, is very close (98%) to Indian brinjal little leaf (EF186820) and “Candidatus Phytoplasma trifolii” (AY390261), 16SrVI group phytoplasmas, previously reported from India and Canada respectively. Here, the status of PLL (EF651786) is verified by computer-simulated restriction fragment length polymorphism analysis of 16S rRNA genes of the F2n/R2 sequences of closely related strains of the 16SrVI group using 17 restriction enzymes.
Acta Phytopathologica Et Entomologica Hungarica, 2004
... disturbances, jaundice, gonorrhea, leprosy, inflammation, piles, intestinal infections, diabe... more ... disturbances, jaundice, gonorrhea, leprosy, inflammation, piles, intestinal infections, diabetes and hepatitis viruses A and B (Ahmed, 1998). Extract of P. amarus have also shown positive antibacterial, antifungal, antitumour and antimalarial activity (Farooqi et al., 2000; Tona et al ...
During the winter season of 1996–1997, little leaf disease of psyllium (Plantago ovata) appeared ... more During the winter season of 1996–1997, little leaf disease of psyllium (Plantago ovata) appeared for the first time in the experimental fields of CIMAP at Lucknow. Disease incidence ranged from 15 to 20 percent in severely infected fields with infected plants showing chlorosis, stunted growth, tiny leaves, excessive branching, and reduction in inflorescences. Electron microscopic studies revealed that infected leaf tissues contain numerous pleomorphic bodies that varied considerably in size (80–750 nm), shape (spherical, oval, some with budding) and electron opacity, and that were bounded by a smooth trilaminar membrane and contained ribosomes-like granules and DNA-like strands. Disease symptoms in infected plants showed remission if treated with tetracycline-HCL. The pathogen, not observed in healthy plants, appears to be a new type of phytoplasma.
This paper reports Portulaca grandiflora as a new host of a Candidatus phytoplasma and demonstrat... more This paper reports Portulaca grandiflora as a new host of a Candidatus phytoplasma and demonstrates its association with the little leaf disease on P. grandiflora. Plants exhibited typical visual symptoms of a phytoplasma, with reduced leaf size. Pleomorphic bodies, observed by transmission electron microscopy, were restricted to the phloem of symptomatic tissue. However, no bacteria, fungi or viruses were observed under transmission electron microscopy. Products of the expected size were amplified by PCR using nested, phytoplasma-specific primer pairs. In addition, plants temporarily showed amelioration of phytoplasma symptoms following treatment with the antibiotic tetracycline.
A new disease of Trachyspermum ammi, commonly known as Ajwain in India, was observed in Lucknow, ... more A new disease of Trachyspermum ammi, commonly known as Ajwain in India, was observed in Lucknow, India. The symptoms included small chlorotic leaves, highly proliferating shoots, witches’ broom appearance, shortened internodes and an overall stunted growth. Poor flower heads and fruit setting caused considerable yield losses for farmers. In transmission electron microscopy, pleomorphic bodies were detected in the phloem cells of diseased plants but not in those of healthy plants. The disease etiology was investigated using direct and nested polymerase chain reaction with phytoplasma-specific primers, DNA sequencing, and phylogenetic analysis. Phylogenetic analysis indicated that this phytoplasma clustered in the 16SrVI group. A 1,249 bp sequence (FJ970035) of the 16S rRNA gene from the phytoplasma showed 99% homology with the 16S rRNA gene, (FJ427295) of Ca. Phytoplasma trifolii strain A6 belonging to the phytoplasma group VI (reported from Iran). This is the first report of phytoplasma infection affecting Ajwain (T. ammi).
Alterations in essential oil gland number, distribution and fine structure, and the oil content i... more Alterations in essential oil gland number, distribution and fine structure, and the oil content in the leaf of Mentha arvensis L. were examined during its growth and senescence. Accumulation of essential oil occurred predominantly during the rapid leaf expansion phase followed by a similar decline. The oil gland (trichome) number increased upto leaf maturation and declined thereafter. Initially, cuticle remains tightly apposed to the secretory head of oil glands but progressively a sub-cuticular space appears to be created for the oil. Considerable enlargement of vacuole with ageing is witnessed, whereas cytoplasm gradually decreases to a thin peripheral layer. Some secretory cells from senescing leaf were found almost empty, having only a few remnant oil droplets.
Archives of Phytopathology and Plant Protection, 2011
A new severe little leaf disease was observed on P. grandiflora, popular as Moss-rose Purslane, w... more A new severe little leaf disease was observed on P. grandiflora, popular as Moss-rose Purslane, widely grown in temperate zones. Characteristic symptoms, ultrastructural studies, antibiotic response and amplification of 16S ribosomal DNA fragments (about 1.5 kb) by polymerase chain reaction (PCR) from infected samples, suspect the involvement of phytoplasma as a pathogen. Nested PCR product, 1.2 kb, with primer pairs R16F2n/R16R2 used for cloning and sequencing. Comparision of the 16S rRNA gene sequences showed that the causal, PLL phytoplasma, is very close (98%) to Indian brinjal little leaf (EF186820) and “Candidatus Phytoplasma trifolii” (AY390261), 16SrVI group phytoplasmas, previously reported from India and Canada respectively. Here, the status of PLL (EF651786) is verified by computer-simulated restriction fragment length polymorphism analysis of 16S rRNA genes of the F2n/R2 sequences of closely related strains of the 16SrVI group using 17 restriction enzymes.
Acta Phytopathologica Et Entomologica Hungarica, 2004
... disturbances, jaundice, gonorrhea, leprosy, inflammation, piles, intestinal infections, diabe... more ... disturbances, jaundice, gonorrhea, leprosy, inflammation, piles, intestinal infections, diabetes and hepatitis viruses A and B (Ahmed, 1998). Extract of P. amarus have also shown positive antibacterial, antifungal, antitumour and antimalarial activity (Farooqi et al., 2000; Tona et al ...
During the winter season of 1996–1997, little leaf disease of psyllium (Plantago ovata) appeared ... more During the winter season of 1996–1997, little leaf disease of psyllium (Plantago ovata) appeared for the first time in the experimental fields of CIMAP at Lucknow. Disease incidence ranged from 15 to 20 percent in severely infected fields with infected plants showing chlorosis, stunted growth, tiny leaves, excessive branching, and reduction in inflorescences. Electron microscopic studies revealed that infected leaf tissues contain numerous pleomorphic bodies that varied considerably in size (80–750 nm), shape (spherical, oval, some with budding) and electron opacity, and that were bounded by a smooth trilaminar membrane and contained ribosomes-like granules and DNA-like strands. Disease symptoms in infected plants showed remission if treated with tetracycline-HCL. The pathogen, not observed in healthy plants, appears to be a new type of phytoplasma.
This paper reports Portulaca grandiflora as a new host of a Candidatus phytoplasma and demonstrat... more This paper reports Portulaca grandiflora as a new host of a Candidatus phytoplasma and demonstrates its association with the little leaf disease on P. grandiflora. Plants exhibited typical visual symptoms of a phytoplasma, with reduced leaf size. Pleomorphic bodies, observed by transmission electron microscopy, were restricted to the phloem of symptomatic tissue. However, no bacteria, fungi or viruses were observed under transmission electron microscopy. Products of the expected size were amplified by PCR using nested, phytoplasma-specific primer pairs. In addition, plants temporarily showed amelioration of phytoplasma symptoms following treatment with the antibiotic tetracycline.
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Papers by Ajayakumar P V