Rajaram Panneerselvam

Antioxidant defense responses: physiological plasticity in higher plants under abiotic constraints.

Environmental stresses (salinity, drought, heat/cold, light and other hostile conditions) may trigger in plants oxidative stress, generating the formation of reactive oxygen species (ROS). These species are partially reduced or activated derivatives of oxygen, comprising both free radical

Differential responses in water use efficiency in two varieties of Catharanthus roseus under drought stress

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ROS Scavenging System, Osmotic Maintenance, Pigment and Growth Status of Panicum sumatrense Roth. Under Drought Stress

and non-radical (H2O2) forms, leading to cellular damage, metabolic disorders and senescence processes. In order to overcome oxidative stress, plants have developed two main antioxidants defense mechanisms that can be classified as non-enzymatic and enzymatic systems. The first class (non-enzymatic) consists of small molecules such as vitamin (A, C and E), glutathione, carotenoids and phenolics that can react directly with the ROS by scavenging them. Second class is represented by enzymes among them superoxide dismutase, peroxidase and catalase which have the capacity to eliminate superoxide and hydrogen peroxide. In this review, we have tried to explore the related works, which have revealed the changes in the basic antioxidant metabolism of plants under various abiotic constraints.

Endogenous hormonal and enzymatic responses of Catharanthus roseus with triadimefon application under water deficits.

Water is vital for plant growth, development and productivity. Permanent or temporary water deficit stress limits the growth and distribution of natural and artificial vegetation and the performance of cultivated plants (crops) more than any other environmental factor. Productive and sustainable agriculture necessitates growing plants (crops) in arid and semiarid regions with less input of precious resources such as fresh water. For a better understanding and rapid improvement of soil–water stress tolerance in these regions, especially in the water-wind eroded crossing region, it is very important to link physiological and biochemical studies to molecular work in genetically tractable model plants and important native plants, and further extending them to practical ecological restoration and efficient crop production. Although basic studies and practices aimed at improving soil water stress resistance and plant water use efficiency have been carried out for many years, the mechanisms involved at different scales are still not clear. Further understanding and manipulating soil–plant water relationships and soil–water stress tolerance at the scales of ecology, physiology and molecular biology can significantly improve plant productivity and environmental quality. Currently, post-genomics and metabolomics are very important in exploring anti-drought gene resources in various life forms, but modern agriculturally sustainable development must be combined with plant physiological measures in the field, on the basis of which post-genomics and metabolomics have further practical prospects. In this review, we discuss physiological and molecular insights and effects in basic plant metabolism, drought tolerance strategies under drought conditions in higher plants for sustainable agriculture and ecoenvironments in arid and semiarid areas of the world. We conclude that biological measures are the bases for the solutions to the issues relating to the different types of sustainable development.

Preliminary study on the antimicrobial activity of Enicostemma littorale using different solvents.

Two varieties, rosea and alba, of Catharanthus roseus (L.) G. Don. were screened for their water use efficiency under two watering regimes, viz. 60 and 100% filed capacity in the present study. Drought stress was imposed at 60% filed capacity from 30 to 70 days after sowing, while the control pots were maintained at 100% filed capacity throughout the entire growth period. Leaf area duration, cumulative water transpired, water use efficiency, net assimilation rate, mean transpiration rate, harvest index, biomass and yield under the water deficit level were measured from both stressed and well-watered control plants. Water use efficiency significantly increased in both varieties under water stress. Drought stress decreased leaf area duration, cumulative water transpired, net assimilation rate, mean transpiration rate, harvest index, and biomass yield in both varieties studied. Among the varieties, rosea variety showed the best results.

Assessment of diversity among populations of Rauvolfia serpentina Benth. Ex. Kurtz. from Southern Western Ghats of India, based on chemical profiling, horticultural traits and RAPD analysis.

Triadimefon, potential fungicide cum plant-growth retardant was used in this study to investigate its effect on the growth and the photosynthetic pigment contents of two varieties of Catharanthus roseus (L.) G. Don. The plants of both varieties were subjected to 15 mg l(-1) triadimefon treatment by soil drenching 30, 45, 60, and 75 days after planting (DAP). Plants were uprooted on 90 DAP, and morphological parameters, like plant height, number of leaves, leaf area, root length and fresh and dry weights were determined. The photosynthetic pigments, like chlorophylls a and b, total chlorophyll, carotenoids, floral pigment, anthocyanin, were extracted and estimated. It was observed that plant height, number of leaves and leaf area were decreased and that root length, fresh and dry weights were increased under triadimefon treatment. The photosynthetic and floral pigments were increased under triadimefon treatment in both varieties. The results suggest that the application of this plant-growth retardant (triadimefon) has favourable effects on the reduction of plant height; it can thus be used for replacing manual hand pruning and for improving floral and vegetation colour in bedding plants like C. roseus.

In vitro propagation and antibacterial activity of Clitoria ternatea Linn.

Drought stress is one of the abiotic stresses and it may alter plant growth, metabolism and yield. The present study aims to analyze the growth, chlorophyll pigments, osmotic adjustment and antioxidative enzymes activity in Panicum sumatrense under drought stress. The control was irrigated daily and treated plants were irrigated at 4-, 7-, 10-, 13-day intervals. Later, they were irrigated at 3-day interval up to 70 DAS. The root and leaf samples were collected on 30 DAS, 50 DAS and 70 DAS and used for analysis. The root length increased gradually in all drought treatments at all growth stages of P. sumatrense. The chlorophyll pigments and plant height showed a reduction in 13 DID treatment when compared to all treatment. Compatible solutes like proline, glycine betaine and free amino acid increased in all drought treatment when compared to control at 70 DAS. Furthermore, stress treatment caused an increase in activity of antioxidant enzymes like superoxide dismutase, catalase and peroxidase. Panicum sumatrense possess many growth and physiological drought tolerance characters which can be used in future breeding program.

Micropropagation and Phenolic exudation protocol for Excoecaria agallocha-an important mangrove

The effect of triadimefon was investigated in a medicinal plant, Catharanthus roseus subjected to water deficit stress. The abscisic acid (ABA) level, DNA and RNA contents and activities of ATPase and protease were found varying in different parts of the plants under treatment. Drought treatment increased the ABA level more than twofold in all parts of the plants. TDM treatment to the drought stressed plants showed highest contents. In roots, stem and leaves, drought stress caused a decrease in the DNA and RNA contents when compared with control and other treatments. TDM treatment with drought increased the nucleic acid contents to the level of the control roots. The activity of ATPase and protease were increased under drought treatment and lowered due to TDM applications. This information could be useful in the field of soil water deficits reclamation efforts by using plant growth regulators.