Publications by authors named "Venkatesan Radhika"

The pervasive application of chemical pesticides is globally recognised for its effectiveness and cost-efficiency in controlling pest populations. However, this approach has inadvertently impacted a diverse array of organisms, including humans and beneficial insects, notably those that naturally regulate pest populations. This review synthesises current research on both the direct and indirect effects of pesticides on parasitoid wasps.

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Plants, being sessile, are prone to genotoxin-induced macromolecule damage. Among the inevitable damaging agents are reactive carbonyls that induce glycation of DNA, RNA and proteins to result in the build-up of advanced glycated end-products. However, it is unclear how plants repair glycated macromolecules.

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Insect herbivores frequently must balance host plant quality and the risk of attack by their natural enemies when making oviposition decisions. Yet, which factor is more important remains unresolved in plant-insect ecology. Here, we report the oviposition preference and larval performance of the brassicaceous specialist Plutella xylostella, in the context of plant quality (cabbage Brassica oleracea vs.

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Cyclotides, a class of macrocyclic plant peptides, characterized by a cyclic backbone and three inter-locking disulfide bonds, may be divided into two major structural subfamilies, Möbius and Bracelet, based on the presence or absence of a specific proline residue. The present study describes the suite of cyclotides obtained from Clitoria ternatea, characterized by LC-MS and MS/MS techniques. Notable variations in product ion distributions were observed in cyclotides belonging to different structural subfamilies based on the number and positions of proline residues.

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Animals possess conserved mechanisms to detect pathogens and to improve survival in their presence by altering their own behavior and physiology. Here, we utilize Caenorhabditis elegans as a model host to ask whether bacterial volatiles constitute microbe-associated molecular patterns. Using gas chromatography-mass spectrometry, we identify six prominent volatiles released by the bacterium Pseudomonas aeruginosa.

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Neurotoxic aggregation of β-amyloid (Aβ) peptides is a hallmark of Alzheimer's disease and increased reactive oxygen species (ROS) is an associated process. In the present study, we report the neuroprotective effects of disulfide-rich, circular peptides from () (butterfly pea) on Aβ-induced toxicity in transgenic . Cyclotides (∼30 amino acids long) are a special class of cyclic cysteine knot peptides.

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Clitoria ternatea a perennial climber of the Fabaceae family, is well known for its agricultural and medical applications. It is also currently the only known member of the Fabaceae family that produces abundant amounts of the ultra-stable macrocyclic peptides, cyclotides, across all tissues. Cyclotides are a class of gene-encoded, disulphide-rich, macrocyclic peptides (26-37 residues) acting as defensive metabolites in several plant species.

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The ecology and distribution of many bacteria is strongly associated with specific eukaryotic hosts. However, the impact of such host association on bacterial ecology and evolution is not well understood. Bacteria from the genus Methylobacterium consume plant-derived methanol, and are some of the most abundant and widespread plant-associated bacteria.

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Plants emit a specific blend of volatiles in response to herbivory and these volatiles, which often attract predators and parasitoids function as an indirect plant defense. The impact of plant volatiles in shaping herbivore defenses is unclear. Here, we report that specific plant volatiles induce immune responses in the polyphagous herbivore, Spodoptera litura.

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Cytokinins (CKs), a class of phytohormones that regulate plant growth and development, are also synthesized by some phytopathogens to disrupt the hormonal balance and to facilitate niche establishment in their hosts. Rhodococcus fascians harbors the fasciation (fas) locus, an operon encoding several genes homologous to CK biosynthesis and metabolism. This pathogen causes unique leafy gall symptoms reminiscent of CK overproduction; however, bacterial CKs have not been clearly correlated with the severe symptoms, and no virulence-associated unique CKs or analogs have been identified.

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Jasmonate-mediated regulation of VOC emission has been extensively investigated in higher plants, however, only little is known about VOC production and its regulation in ferns. Here, we investigate whether the emission of VOCs from bracken fern Pteridium aquilinum is triggered by herbivory and if so - whether it is regulated by the octadecanoid signaling pathway. Interestingly, feeding of both generalist (Spodoptera littoralis) and specialist (Strongylogaster multifasciata) herbivores as well as application of singular and continuous mechanical wounding of fronds induced only very low levels of VOC emission.

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Ant-plant interactions often are mediated by extrafloral nectar (EFN) composition that may influence plant visitation by ants. Over a 300 km range in the Indian Western Ghats, we investigated the correlation between the EFN composition of the myrmecophytic ant-plant Humboldtia brunonis (Fabaceae) and the number and species of ants visiting EFN. EFN composition varied among H.

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To maximize fitness, plants need to perceive changes in their light environment and adjust their physiological responses accordingly. Whether and how such changes also affect the regulation of their defense responses against herbivores remains largely unclear. We addressed this issue by studying the secretion of extrafloral nectar (EFN) in lima bean (Phaseolus lunatus), which is known to be activated by the phytohormone jasmonic acid (JA) and functions as an indirect defense mechanism against herbivores.

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Nectar is a rich source of sugars that serves the attraction of pollinators (floral nectar) or predatory arthropods (extrafloral nectar). We just begin to understand the similarities and differences that underlie the secretory control of these two important types of plant secretions. Jasmonates are phytohormones, which are well documented to be involved in plant developmental processes and plant defence responses against herbivores, including the secretion of extrafloral nectar.

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Plants produce nectar in their flowers as a reward for their pollinators and most of our crops depend on insect pollination, but little is known on the physiological control of nectar secretion. Jasmonates are well-known for their effects on senescence, the development and opening of flowers and on plant defences such as extrafloral nectar. Their role in floral nectar secretion has, however, not been explored so far.

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Many plants respond to herbivory with an increased production of extrafloral nectar (EFN) and/or volatile organic compounds (VOCs) to attract predatory arthropods as an indirect defensive strategy. In this study, we tested whether these two indirect defences fit the optimal defence hypothesis (ODH), which predicts the within-plant allocation of anti-herbivore defences according to trade-offs between growth and defence. Using jasmonic acid-induced plants of Phaseolus lunatus and Ricinus communis, we tested whether the within-plant distribution pattern of these two indirect defences reflects the fitness value of the respective plant parts.

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