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21 results on '"Prabavathy, V. R."'

11. Acyl Homoserine Lactone-Producing Rhizobacteria Elicit Systemic Resistance in Plants

Author

Prabavathy V. R, Jegan Sekar, and Ganga Viswanath

Subjects
0301 basic medicine, Rhizosphere, biology, fungi, 030106 microbiology, Homoserine, Defence mechanisms, food and beverages, biochemical phenomena, metabolism, and nutrition, Plant cell, Rhizobacteria, biology.organism_classification, Microbiology, 03 medical and health sciences, chemistry.chemical_compound, Quorum sensing, 030104 developmental biology, chemistry, Biochemistry, Gene, Bacteria
Abstract

N-acyl homoserine lactone (AHLs) produced by bacteria play a unique role in altering the expression of plant defence genes. AHL signals are constitutively produced by the vast majority of the rhizosphere and other groups of bacteria; and also varied levels of plant response are elicited through different types of AHL signals. Moreover, the defence mechanism of AHL-induced ISR is distinct from other bacterial compound-mediated plant response. It was also evident that the response of plants to bacterial AHLs may depend on plant species and chemical structure of AHLs. However, the question of how plants perceive the AHLs and distinguish between those molecules remains open. To date, no information is available either about plant AHL receptors or how plant cells can incorporate AHL signal molecules. Even though plants produce compounds similar to AHL signals, the precise source, structure and biological significance of these AHL mimics from plants are currently unknown. The specificity of plant mimics to stimulate or inhibit different types of AHL signals needs to be addressed. A thorough understanding of how plants perceive and respond to AHLs needs to be investigated. Copious questions remain to be addressed for the better understanding of quorum sensing of bacteria and trans-kingdom interactions of AHLs with plant cells.

Published
2016
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18. The Effect of Fungal Secondary Metabolites on Bacterial and Fungal Pathogens.

Author

Varma, Ajit, Karlovsky, Petr, Mathivanan, N., Prabavathy, V. R., and Vijayanandraj, V. R.

Abstract

Fungi are an extremely diverse group of organisms, with about 230,000 species distributed widely essentially in every ecosystem. Among them, only limited species are considered to be effective biocontrol agents. The fungal antagonists restrict the growth of plant pathogens by the three suggested mechanisms: antibiosis, competition and parasitism. Besides, they also induce the defense responses in host plants, termed "induced systemic resistance" (van Loon et al. 1998). Among the abovementioned mechanisms, antibiosis is considered the most important, in which the antagonists produce an array of secondary metabolites such as antibiotics and toxin, which contribute to the antagonistic activity of fungal biocontrol agents against plant pathogens. Antagonistic strains belonging to the Trichoderma and Fusarium genera were able to produce various secondary metabolites which can play a role in the mechanism of their biological activity (http://www.item.ba.cnr.it/biopesti.htm). Production of antimicrobial secondary metabolites has been reported in many fungal biocontrol agents (Gottlieb and Shaw 1970; Fries 1973; Hutchinson 1973; Sivasithamparam and Ghisalberti 1998; Vyas and Mathur 2002). In this review, we highlight the secondary metabolites of selected fungal biocontrol agents and their involvement in the control of plant pathogens. [ABSTRACT FROM AUTHOR]

Published
2008
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19. Symbiotic effect of Bradyrhizobium yuanmingense isolates over Bradyrhizobium japonicum with soybean.

Author

Appunu, C., Kumar, Ravinder, Sreenivasa, V., Manjunatha, T., Mahadevaiah, C., Sasirekha, N., Prabavathy, V. R., and Nair, Sudha

Subjects
BRADYRHIZOBIUM, BRADYRHIZOBIUM japonicum, SOYBEAN, CROP yields, INOCULATION (Founding)
Abstract

Symbiotic effect of twenty one indigenous Bradyrhizobium yuanmingense strains obtained from nodules of soybean cultivated in India was comparatively evaluated with B. japonicum ASR011 on soybean cv. JS335 for improved nodulation and plant growth performance under greenhouse conditions. Significant variation in symbiotic potential among native B. yuanmingense strains was observed and few of them exhibited significantly superior symbiotic performance i.e. improved the shoot and root dry weights and shoot N content compared to non-inoculated plants and over B. japonicum inoculated plants. The symbiotically efficient B. yuanmingense strains may have applications in the formulation of appropriate inocula to improve soybean crop yield on Indian soils. [ABSTRACT FROM AUTHOR]

Published
2015
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20. Antimicrobial properties of Cipadessa baccifera and Melia dubia against hum pathogens.

Author

Malarvannan, S., Lavanya, M., Prabavathy, V. R., and Nair, Sudha

Subjects
*ANTI-infective agents, *MEDICINAL plants, *PATHOGENIC microorganisms, *SOLVENT extraction, *COMMUNICABLE diseases
Abstract

Cipadessa baccifera Miq., and Melia dubia (Cav.) (Meliaceae) are common medicinal plants found in Western Ghats and are used traditionally for various purposes. The solvent extracts of the leaves and primary fractions of the tested plants were used for their anti-microbial properties following the disc diffusion method against human pathogens. The chloroform extract of C. baccifera and petroleum ether extract of M. dubia were the most effective. Cipadessa chloroform fraction 4 and Melia petroleum ether fraction 2 exhibited maximum zone of inhibition for almost all the pathogens tested. [ABSTRACT FROM AUTHOR]

Published
2009

21. Self-fusion of protoplasts enhances chitinase production and biocontrol activity in Trichoderma harzianum.

Author

Prabavathy VR, Mathivanan N, Sagadevan E, Murugesan K, and Lalithakumari D

Subjects
Plant Diseases, Rhizoctonia, Trichoderma physiology, Chitinases biosynthesis, Protoplasts physiology, Trichoderma metabolism
Abstract

Protoplasts were isolated from Trichoderma harzianum strain PTh18 using lysing enzymes and self-fusion of T. harzianum protoplasts was carried out using polyethylene glycol in STC buffer. The fused protoplasts of T. harzianum were regenerated and 15 self-fusants were selected to study the chitinase production and biocontrol activity. High chitinase activity was measured in the culture filtrates of most of the self-fusants (87%) than the parent. Among the fusants, the strain SFTh8 produced maximum chitinase with a two-fold increase as compared to the parent strain. All the self-fusants exhibited increased antagonistic activity against Rhizoctonia solani than the parent. The crude chitinase preparation of SFTh8 lysed the mycelia of T. harzianum, Trichoderma viride and Trichoderma reesei and released the protoplasts in higher number than the crude chitinase preparation of parent strain PTh18.

Published
2006
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