Tummala P. Reddy

Molecular characterization, physicochemical properties, known and potential applications of phytases: An overview

Phytases (myo-inositol hexakisphosphate phosphohydrolases) hydrolyze the phosphate ester bonds of phytate-releasing phosphate and lower myo-inositol phosphates and/or myo-inositol. Phytases, in general, are known to enhance phosphate and mineral uptake in monogastric animals such as poultry, swine, and fish, which cannot metabolize phytate besides reducing environmental pollution significantly. In this study, the molecular, biophysical, and biochemical properties of phytases are reviewed in detail. Alterations in the molecular and catalytic properties of phytases, upon expression in heterologous hosts, are discussed. Diverse applications of phytases as feed additives, as soil amendment, in aquaculture, development of transgenic organisms, and as nutraceuticals in the human diet also are dealt with. Furthermore, phytases are envisaged to serve as potential enzymes that can produce versatile lower myo-inositol phosphates of pharmaceutical importance. Development of phytases with improved attributes is an important area being explored through genetic and protein engineering approaches, as no known phytase can fulfill all the properties of an ideal feed additive.

Current status of genetic engineering in cotton (Gossypium hirsutum L): an assessment.

Abstract Cotton is considered as the foremost commercially important fiber crop and is deemed as the backbone of the textile industry. The productivity of cotton crop, worldwide, is severely hampered by the occurrence of pests, weeds, pathogens apart from various environmental factors. Several beneficial agronomic traits, viz., early maturity, improved fiber quality, heat tolerance, etc. have been successfully incorporated into cotton varieties employing conventional hybridization and mutation breeding. Crop losses, due to biotic factors, are substantial and may be reduced through certain crop protection strategies. In recent years, pioneering success has been achieved through the adoption of modern biotechnological approaches. Genetically engineered cotton varieties, expressing Bacillus thuringiensis cry genes, proved to be highly successful in controlling the bollworm complex. Various other candidate genes responsible for resistance to insect pests and pathogens, tolerance to major abiotic stress factors such as temperature, drought and salinity, have been introduced into cotton via genetic engineering methods to enhance the agronomic performance of cotton cultivars. Furthermore, genes for improving the seed oil quality and fiber characteristics have been identified and introduced into cotton cultivars. This review provides a brief overview of the various advancements made in cotton through genetic engineering approaches.

Synergistic interaction of gamma rays and some metallic salts in the induction of chlorophyll mutations in rice

Abstract In this study the mutagenic activity of 9 metallic salts was tested in comparison and conjunction with gamma rays on rice seed. In M 2 , barium and cadmium produced chlorophyll mutation and mutant frequencies on a par with those of 20 kR gamma rays. Similarly, copper and mercury induced moderately high mutation and mutant frequencies. Salts of strontium, iron and lead showed rather weak mutagenic effects. On the other hand, two metals — manganese and calcium — failed to provoke chlorophyll mutations in rice seed. Sequential treatments of gamma rays + 5 metals, namely Sr, Cd, Hg, Pb and Cu, produced synergistic yields of chlorophyll mutants in the M 2 generation. Two genetically active metals, Ba and Fe, showed less than additive effects when post-treated after gamma irradiation. Manganese, which failed to induce chlorophyll mutations in independent treatment, potentiated the mutagenic activity of gamma radiation in sequential treatment. On the other hand, sequential treatment with calcium seemed to confer a substantial protection against gamma-ray-induced genetic lesions. The probable mechanisms of synergistic interaction, mutagenic potentiation and protection, observed in sequential treatments, are discussed.

Interaction of certain base-specific chemicals and diethylsulphate in the induction of chlorophyll mutations in Oryza sativa L.

Abstract The presoaked seeds of a rice cultivar, Tellakattera, were treated with three different concentrations of hydrazine (HZ) or hydroxylamine (HA) in combination with diethylsulphate (dES) (0.05%). In the M 1 generation more than additive effects were observed for increase in chlorophyll chimeras and decrease in seed fertility. A synergistic effect was also observed for both chlorophyll mutation and mutant frequencies, in the M 2 generation, in sequential treatments. However, the degree of synergism, based on M 2 chlorophyll mutant frequency, was greater in dES posttreatment combinations with HA or HZ, compared with dES pretreatments. These differences in reciprocal treatments may be due to more efficient fixation of premutational events by dES than HZ or HA.

Enhancement of gamma ray-induced mutation frequency in rice by post-treatment with chloral hydrate, methanol and their mixtures with ethanol

Abstract This study is an evaluation of the mutagenic activity of ethanol, chloral hydrate (CH) and methanol on rice seed. In independent treatments with ethanol, methanol, CH and four aqueous mixtures of these chemicals chlorophyll-deficient mutants were not recovered in the M 2 generation. However, in sequential treatments with gamma rays + CH, gamma rays + methanol and gamma rays + aqueous mixtures of these chemicals, significant increases in the yields of chlorophyll mutations were observed as compared to that of a 30 kR gamma ray treatment. In contrast, post-irradiation treatment with ethanol failed to provoke any increase in the frequency of chlorophyll mutants in the M 2 generation. The results indicate that CH and methanol alone and mixed with ethanol can potentiate gamma ray-induced genetic lesions in rice seed.

Mutagenic effect of argemone oil in Oryza sativa L.

In view of the large scale adulteration of edible oils with Argemone oil, a study was undertaken to test its mutagenicity on rice seed. In treatment with screw-pressed oil a marked reduction in seed germination and high chlorophyll mutation and mutant frequencies were observed. In sequential treatments between gamma rays and Argemone oil both mutation and mutant frequencies were significantly higher than that of individual treatments. This study clearly indicates that Argemone oil is a potent mutagen with serious implications for the genetic hygiene of human beings.

Genetic Affinities of Jatropha with Other Euphorbiaceous Taxa

The genetic relatedness of Jatropha with other economically important members of the family Euphorbiaceae has been studied. Keeping in view the morphological resemblances of different species of the genus Jatropha, particularly with Ricinus, attempts were made at intergeneric hybridization between the two genera. Protein and molecular profiles showed that Ricinus is genetically distant to Jatropha. Intergeneric crosses and pollen-pistil interactions revealed that the sexual crossability between members of these two genera is limited by incongruity rather than a genetically-controlled incompatibility mechanism. Genome sequencing and molecular phylogenetic studies of different Euphorbiaceous genera indicated the relatedness of Jatropha with cassava (Manihot esculenta). In the recent past, molecular markers and microsatellite markers viz., genic and genomic SSRs developed for Hevea, Manihot, Ricinus and Jatropha are being tested for cross-taxa transferability to facilitate marker-assisted breeding programmes. Likewise, with the draft genomes in place for castor and jatropha – besides the framework linkage maps of Hevea and cassava – it should be feasible to analyze and unravel the various regulatory mechanisms through structural and functional genomics.