Chromium-induced accumulation of peroxide content, stimulation of antioxidative enzymes and lipid peroxidation in green gram (Vigna radiata L. cv. Wilczek) leaves

Chromium (Cr)-induced oxidative damage and changes in contents of chlorophyll, protein, peroxide and malondialdehyde (MDA) and activities of enzymatic antioxidants were investigated in 4-day-old green gram (Vigna radiata L. cv. Wilczek) seedlings. Cr increased the contents of peroxide and MDA but decreased the contents of chlorophyll and proteins. Cr reduced the activities of catalase (CAT) and glutathione reductase (GR), but increased the activity of superoxide dismutase (SOD) in green gramleaves. Lipid peroxidation is considered to be an important mechanism of Cr-induced oxidative damage in green gram leaves. The peroxidation of lipids can be initiated by free radicals. The effects of Crinducedoxidative damage and increase in the contents of peroxide and MDA in green gram leaves can be minimized by pretreatment with ascorbic acid (AA) and reduced glutathione (GSH) or both

Genetic diversity in green gram [Vigna radiata (L.)] landraces analyzed by using random amplified polymorphic DNA (RAPD)

Green gram [Vigna radiata (L.)] landraces were collected from various localities of Southern Tamil Nadu, India, to determine the extent of genetic diversity at DNA level by random amplified polymorphic DNA (RAPD) analysis using 20 decamer primers. All the primers produced polymorphic amplificationproducts with some extent of variation. A total of 200 bands were generated with an average of 10 per primer and exhibited 83.0% polymorphism. Jaccard’s similarity coefficient ranged from 0.64 to 0.93 and concentrated mostly between 0.76 to 0.93. This indicated a rather narrow genetic base of tested green gram landraces. Clustering of green gram landraces into two groups showed reasonable variability that may be exploited for selecting parents for breeding purposes. Generally distinct phenotypes identifiedusing RAPD markers could be potential sources of germplasm for green gram improvemen

Insight into the Molecular Evolution of Non-Specific Lipid Transfer Proteins via Comparative Analysis Between Rice and Sorghum

Phylogenetic analysis was conducted on 9 kDa non-specific lipid transfer protein (nsLTP) genes from nine plant species. Each of the five classified types in angiosperms exhibited eight conserved cysteine patterns. The most abundant nsLTP genes fell into the type I category, which was particularly enriched in a grass-specific lineage of clade I.1. Six pairs of tandem copies of nsLTP genes on the distal region of rice chromosomes 11 and 12 were well-preserved under concerted evolution, which was not observed in sorghum. The transgenic promoter–reporter assay revealed that both rice and sorghum nsLTP genes of type I displayed a relatively conserved expression feature in the epidermis of growing tissue, supporting its functional roles in cutin synthesis or defence against phytopathogens. For type I, the frequent expression in the stigma and seed are indicative of functional involvement in pistil–pollen interactions and seed development. By way of contrast, several type V genes were observed, mainly in the vascular bundle of the rosette as well as the young shoots, which might be related with vascular tissue differentiation or defence signalling. Compared with sorghum, the highly redundant tissue-specific expression pattern among members of rice nsLTP genes in clade I.1 suggests that concerted evolution via gene conversion favours the preservation of crucial expression motifs via the homogenization of proximal promoter sequences under high selection constraints. However, extensive regulatory subfunctionalization might also have occurred under relative low selection constraints, resulting in functional divergence at the expression level

Biotechnological Perspective of Reactive Oxygen Species (ROS)-Mediated Stress Tolerance in Plants

All environmental cues lead to develop secondary stress conditions like osmotic and oxidative stress conditions that reduces average crop yields by more than 50% every year. The univalent reduction of molecular oxygen (O2) in metabolic reactions consequently produces superoxide anions (O2•−) and other reactive oxygen species (ROS) ubiquitously in all compartments of the cell that disturbs redox potential and causes threat to cellular organelles. The production of ROS further increases under stress conditions and especially in combination with high light intensity. Plants have evolved different strategies to minimize the accumulation of excess ROS like avoidance mechanisms such as physiological adaptation, efficient photosystems such as C4 or CAM metabolism and scavenging mechanisms through production of antioxidants and antioxidative enzymes. Ascorbate-glutathione pathway plays an important role in detoxifying excess ROS in plant cells, which includes superoxide dismutase (SOD) and ascorbate peroxidase (APX) in detoxifying O2•−radical and hydrogen peroxide (H2O2) respectively, monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) involved in recycling of reduced substrates such as ascorbate and glutathione. Efficient ROS management is one of the strategies used by tolerant plants to survive and perform cellular activities under stress conditions. The present chapter describes different sites of ROS generation and and their consequences under abiotic stress conditions and also described the approaches to overcome oxidative stress through genomics and genetic engineering

A preliminary study on the environmental condition of the coral reef habitat

The present investigation was carried in coral reef areas of Palk Bay, Madapam. Palk Bay corals were found disturbed by human beings due to oil pollution, waste discharge from processing units and discharge of domestic household wastes from the nearby Mandapam town. Environmental conditions of the coral reef habitat in the Palk Bay, Mandapam was analyzed for a period of six months at fortnightly intervals for March to August 2001 on the coral reef areas. Temperature, pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD) and Total Organic Carbon (TOC) were analyzed at five different stations of Palk Bay, Madapam. The maximum mean values of temperature, pH, DO, BOD and TOC for the four experimental and control stations were 32.6°C, 8.7, 7.02ppm, 8.29ppm and 2.13% and 31.5°C, 8.3, 7.98ppm, 5.71ppm and 0.48% respectively. The sampling stations were selected on the basis of their importance