Inhibition of Chlorophyll Synthesis and Enzymes of Nitrogen Assimilation by Selenite in Excised Maize Leaf Sefments during Greening

Supply of 0.1 mM sodium selenite (Na₂SeO₃ to excised maize leaf segments during greening reduced total chorophylls and inhibited in vivo nitrate reductase activity (NRA). Inhibition of chlorophyll formation by selenite was affected by ammonium but remained unaltered by nitrate. Selenite also inhibited NADH-glutamate dehydrogenase (NADH-GDH) and NADH-glutamate synthase (NADH-GOGAT) activities. Inclusion of ammonium enhanced the inhibition of NADH-GDH activity by selenite but decreased the inhibition of NADH-GOGAT activity by selenite. The results suggest the involvement of the glutamine synthetase/glutamate synthase (GS/GOGAT) pathway of ammonia assimilation in selenite toxicity during chlorophyll formation in greening maize leaf segments.     

Productivity and Cytogenetic Analysis of an Unbranched Mutant in Hyoscyamus niger L.

An unbranched mutant (Ub) with marginal arrangement of large leaves substantially altered floral and reproductive features in H. niger was isolated in M₂. It bred true for all mutant characteristics in M₂ generation. Appearance of restricted branching (Rb mutant) in some M₃ families seems 10 be a transient phase. Erect growth habit Coupled with non-overlapping leaf-disposition is useful for high crop density to obtain higher biomass field and, in turn, more crude drug production per unit area. Improvement in alkaloid content is an additional advantage augmenting its economic viability. Seed setting was, however. Poor due to pollen-polymorphism accruing from desynapsis and lack of organized alignment of chromosomes at Ml and subsequent abnormal disjunction at Al.     

Observations on experimental perineal exteriorisation of the bovine urinary bladder.

A new technique for perineal exteriorisation of the urinary bladder was evolved and successfully performed in 15 buffalo calves (Bubalus bubalis). Its merits are maximum visibility of the bladder for cystorrhaphy and easy digital accessibility to the bladder neck. An indwelling urethral catheter made of polyvinyl chloride tubing with an improvised wire stilette was well tolerated for up to 20 days.     

Effect of As on Chlorophyll and Protein Contents and enzymic Activities in Greening Maize Tissues

Arsenic is known to have several phytotoxic effects and one of them is the reduction in chlorophyll content. Determination of chlorophyll content is often accomplished to assess the impact of most environmental stresses, as the pigment content is linked to the visual symptoms and photosynthetic plant productivity. Hence, the present investigation was undertaken to study the effect of As on chlorophyll synthesis with a view to gain some insights into the possible mechanism. Supply of 0.01 to 1.00 mM Na arsenate to the greening maize leaf segments decreased the chlorophyll content as well as chlorophyllase activity, but decline in former was more pronounced than latter at high concentration of As. Supply of arsenate also reduced total RNA, protein and acid soluble thiol content of the tissue. The inhibitory effect of As was less pronounced in the beginning i.e. upto 4 h, but became substantial with increasing time periods. Nitrate reductase activity was inhibited more strongly than chlorophyll formation and was induced only slightly by the supply of inorganic nitrogen in the presence of As. Inclusion of KNO₃ had almost no effect on inhibitory effect of As on chlorophyll formation, while NH₄Cl and NH₄NO₃ substantiated it. Percent decrease in chlorophyll content was reduced by 2-Oxoglutarate, glutamine, glycine and Na succinate, but it was increased by MgCl₂ and remained unaltered by glutamate. Amongst the thio compounds tested, cysteine and 5,5′ dithio bis 2 nitro benzoic acid could overcome the toxic effect of As partially, while mercaptoethanol and dithiothreitol enhanced it and reduced glutathione had no effect. It is suggested that toxic effect of As on chlorophyll biosynthesis involves limited availability of δ-aminolevulinic acid and thiol modulation of proteins.     

In vitro induction and characterization of somaclonal variation for red rot and other agronomic traits in sugarcane

In the present investigation, optimal media compositions for enhancing the callus induction and subsequent plant regeneration were worked out in sugarcane (Saccharum spp. complex). The field grown somaclones were characterized for yield and quality contributing traits in comparison to donor variety CoJ 88. The MS + 2,4-D (4.0 mg/l) + kin (0.5 mg/l) + sucrose (30 g/l) was found to be the best for the callus induction among the nine media compositions used. The highest shoot regeneration was 34.65% on MS + BAP (0.5 mg/l) followed by 31.07% on MS + IAA (2.0 mg/l) + kin (0.5 mg/l) and the least 11.80% on MS + BAP (2.0 mg/l). The shoot elongation was optimum on MS + IBA (5.0 mg/l). The rooting was carried on MS + NAA (3.0 mg/l) + IBA (2.0 mg/l) + sucrose (70 g/l). The somaclones, on field evaluation, exhibited huge variability for characters viz., tiller number at 120 days of field transfer, number of millable canes, cane height, number of nodes and internodal length at time of harvest and also for HR Brix at 240 and 300 days after field transfer. In R₀ generation, the variations induced for the characters such as stalk height after 120 days, HR Brix after 240 and 300 days of field transfer were negatively skewed with most of somaclones having values higher than the population mean values thereby offering adequate scope for improvement cane and quality. Elite somaclones marked for each trait were reported. Out of 228 somaclones inoculated with Cf 08 pathotype of red rot in R₁, three were resistant, four were moderately resistant and 221 somaclones showed variable degree of susceptibility, whereas, to Cf 03 pathotype, fourteen were resistant, nineteen were moderately resistant and 195 showed variable degree of susceptibility. Three somaclones exhibited moderate resistance (MR) to both the pathotypes, whereas, donor variety CoJ 88 showed susceptible reaction. These somaclones will further enhance the germplasm for sugarcane breeding.     

Enhanced productivity of tropane alkaloids and fertility in artificial autotetraploids of Hyoscyamus niger L.

Summary Genetically stable artificial autotetraploids with over 90% seed set were obtained by colchicine treatment of the solanaceous species Hyoscyamus niger L. (2n=4x=68). The tetraploids were vigorous and yielded 22.5% more tropane alkaloid per individual than the source diploids.CIMAP Publication No. 35/90     

Evaluation of bacterial strains isolated from oil-contaminated soil for production of polyhydroxyalkanoic acids (PHA)

Samples of eight geographically distinct soils contaminated with crude oil were screened for polyhydroxyalkanoic acid (PHA) producing bacterial strains. Twenty three bacterial strains were able to accumulate PHA when sodium gluconate or sodium octanoate was used as the sole carbon source. Biochemical tests and 16S rRNA sequencing identified bacteria of the genera Pseudomonas, Acinetobacter, Sphingobacterium, Brochothrix, Caulobacter, Ralstonia, Burkholderia and Yokenella. Three of the bacterial strains have never been reported to produce PHA. The phylogenetic analysis of the PHA synthase (phaC) gene of these bacteria showed a close homology with the phaC gene of different Pseudomonas species.This study indicates that stressed environments like oil-contaminated sites can be potential sources of medium-chain-length PHA producers.     

Evaluation of bacterial strains isolated from oil-contaminated soil for production of polyhydroxyalkanoic acids (PHA)

Samples of eight geographically distinct soils contaminated with crude oil were screened for polyhydroxyalkanoic acid (PHA) producing bacterial strains. Twenty three bacterial strains were able to accumulate PHA when sodium gluconate or sodium octanoate was used as the sole carbon source. Biochemical tests and 16S rRNA sequencing identified bacteria of the genera Pseudomonas, Acinetobacter, Sphingobacterium, Brochothrix, Caulobacter, Ralstonia, Burkholderia and Yokenella. Three of the bacterial strains have never been reported to produce PHA. The phylogenetic analysis of the PHA synthase (phaC) gene of these bacteria showed a close homology with the phaC gene of different Pseudomonas species.This study indicates that stressed environments like oil-contaminated sites can be potential sources of medium-chain-length PHA producers.     

Enhanced productivity of the essential oil in the artificial autopolyploid of vetiver (Vetiveria zizanioides L. Nash)

Summary Artificial autotetraploids were produced by colchicine treatment in the important essential oil bearing vetiver (2n=20). The raw tetraploids were stabilised by selection for pure types in segregating vegetative progeny. The tetraploids were vigorous with thicker and longer roots. The performance data recorded on 17 months' old crop of the tetraploid taken in conjunction with diploid parent and the best available check, exhibited distinct superiority of the tetraploid. In terms of economic yield the tetraploid has the potential of producing 62.5% and 39.2% more oil over the diploid parent and the check, respectively. Although there was marginal improvement in root biomass but significant improvement was registered for percent oil content. The tetraploid produced 1.4% oil in freshly harvested roots compared to 0.98% and 1.15% in the control and check respectively. The study explicitly demonstrate the use of induced tetraploidy in attaining rapid genetic improment even for the characters associated with the secondary metabolism.This paper is dedicated to Professor AK Sharma to commemorate his 40 years association with chromosome research, (CIMAP Publication No. 719).     

Novel mechanism of modulating natural antioxidants in functional foods: involvement of plant growth promoting Rhizobacteria NRRL B-30488

The significance of plant growth-promoting rhizobacteria (PGPR) mediated increase in antioxidant potential in vegetables is yet unknown. The plant growth-promoting bacterium Bacillus lentimorbus NRRL B-30488 (B-30488) mediated induction of dietary antioxidant in vegetables ( Trigonella foenum-graecum, Lactuca sativa, Spinacia oleracea, and Daucus carota) and fruit ( Citrus sinensis) after minimal processing (fresh, boiled, and frozen) was tested by estimating the total phenol content, level of antioxidant enzymes, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide scavenging activities along with integral radical scavenging capacity by photochemiluminescence assay and inhibition of lipid peroxidation. Minimal processing of vegetables showed that T. foenum-graecum had the highest phenol content in B-30488-treated plants followed by L. sativa, D. carota, and S. oleracea. Thermally treated vegetables T. foenum-graecum (26-114.5 GAE microg mg (-1)) had an exceptionally high total phenolic content, followed by D. carota (25.27-101.32 GAE microg mg (-1)), L. sativa (23.22-101.10 GAE microg mg (-1)), and S. oleracea (21.87-87.57 GAE microg mg (-1)). Among the vegetables and fruit used in this study for enzymatic estimation, induction of antioxidant enzymes, namely, polyphenol oxidase (PPO), ascorbate peroxidase (APX), catalase (CAT), and superoxidase dismutase (SOD), was observed in edible parts of T. foenum-graecum, L. sativa, S. oleracea, and D. carota, after inoculation with B-30488. The scavenging capacity of the vegetables treated with B-30488 against DPPH and superoxide anion radical activity was found to be significantly high as compared to nontreated control. Mild food processing had no adverse effect on radical scavenging capacity. Photochemiluminescence also ascertains the above findings. The ability of the plant extracts to protect against lipid peroxidation and its ability to prevent oxidation of reduced glutathione (GSH) was measured in rat liver homogenate, and the results suggested that the inoculated plant exhibited better activity in all of the screened plants. Significant increases in shoot length, root length, and dry weight, averaging 164, 132, and 135% in T. foenum-graecum, 174, 141, and 156% in L. sativa, 129, 141, and 59%, in S. oleracea, and 125, 146, and 42% in D. carota, respectively, over untreated controls, were attained in greenhouse trials. To the best of the authors' knowledge, this is the first report of PGPR-mediated induction of antioxidant enzyme activity (PPO, APX, CAT, and SOD) along with the antioxidant activity of the extracts in both in vitro (DPPH radical scavenging and superoxide scavenging) and ex vivo conditions using the rat liver tissue (percent inhibition of lipid peroxidation and prevention of oxidation of GSH) and phenolic content. The results demonstrate the PGPR-mediated induction of antioxidant level in vegetables and fruit controls oxidative damage even after minimal processing and thus is indicative of its potential as a viable substitute of synthetic antioxidants.