NISCAIR Online Periodicals Repository Community: Indian Journal of Biotechnology (IJBT)

DNA cassette for detection and IPR protection of transgenic Cyanobacteria and Rhizobium strains

Title: DNA cassette for detection and IPR protection of transgenic Cyanobacteria and Rhizobium strains

Authors: Biate, David L; Misra, Arvind K

Abstract: We report the potential utility of using partial 16S ribosomal RNA sequence of Frankia for tagging transgenic Cyanobacteria and Rhizobium strains for addressing intellectual property right (IPR) issues. We have introduced restriction sites in the primers for securing amplification of the distal region of 16S rDNA of Frankia. The amplicon then can be included in the construct for genetic engineering of cyanobacteria or rhizobium and shall remain embedded as a signature for easy identification of the engineered strains. This will help in protecting IPR issues with respect to genetically modified organisms. For this purpose, the Frankia 16S rDNA sequence was amplified using Frankia specific primers targeting ~500 bp at the 3′ end containing helices 34 and 44 that play important role in translation. The 3′ end of the amplified 16S rDNA sequence also contains the Shine-Dalgarno complementary sequence, which is essential for the initiation of translation. Multiple alignments of the 16S rDNA sequences of Frankia sp. were therefore carried out with 84 corresponding 16S rDNA sequences of cyanobacteria and Rhizobium to determine if there was/were any mutation(s) within these regions that could affect translation in the host. The analysis revealed that these regions are highly conserved across the three different bacterial species. Therefore, event of chance recombination between the introduced DNA sequence and the host’s gene is not likely to have any adverse effect on the modified organism. It is also a non-expressing sequence, giving an added ecological advantage to the target host.

Page(s): 103-108

Plant growth promoting rhizobacteria mediated improvement of health status of tea plants

Title: Plant growth promoting rhizobacteria mediated improvement of health status of tea plants

Authors: Chakraborty, U; Chakraborty, B N; Chakraborty, A P; Sunar, K; Dey, P L

Abstract: Plant growth promoting rhizobacteria (PGPR) have immense potential application in sustainable agriculture as ecofriendly biofertilizers and biopesticides. The present study was undertaken to explore the potential of such microorganisms from the rhizosphere of tea [Camellia sinensis (L.) O. Kuntze] for the overall improvement in growth and productivity of tea, which is the most important crop of this region. Isolation and testing of bacteria for PGPR activities revealed that a large number of them showed such activities. Of which three were selected for various studies. The selected bacteria were Bacillus amyloliquefaciens, Serratia marcescens and B. pumilus. These bacteria showed positive PGPR traits in vitro, such as, phosphate solubilization, siderophore production, antagonism to pathogens and IAA production. 16S rDNA sequencing of the bacteria was done and their phylogenetic relationships determined. Under in vivo conditions, the PGPR enhanced the seedling growth of tea varieties in the nursery as well as in the field. Plant growth promotion was determined in terms of increase in number of leaves, their biomass and number of shoots. In order to determine the tolerance of bacteria to insecticides, in vitro tests were conducted, which indicated that PGPR could tolerate more than 100 times the concentration applied in the field. Sustainability of the applied bacteria in soil was tested by PTA-ELISA and Dot immunobinding assay using polyclonal antibodies raised against the PGPR. Certain bioformulations of the PGPR in talc powder, saw dust and rice husk also been prepared and their viability tested. The bacteria showed good survivability even up to 9 months of storage. Application of the PGPR led to enhancement in activities of defense related enzymes, such as, phenyl alanine ammonia lyase, peroxidase, chitinase and β-1,3-glucanase, in tea leaves. Total phenols also increased quantitatively. It is evident from the present study that application of PGPR in the soil lead to biopriming of the plants through induced systemic resistance and other mechanisms.

Page(s): 20-31

In silico analysis of the NBS protein family in Ectocarpus siliculosus

Title: In silico analysis of the NBS protein family in Ectocarpus siliculosus

Authors: Mahmood, Niaz; Moosa, Mahdi Muhammad

Abstract: Nucleotide-binding site (NBS) domain containing proteins belong to one of the most well characterized family of proteins; they are found in almost all higher eukaryotes. Extensive studies have been done on the plant NBS proteins, but similar studies on the brown algae NBS proteins are not available. In the present study, authors examined the diversity of NBS proteins in model brown algae, Ectocarpus siliculosus. A total of twenty six NBS proteins were identified and classified into different subfamilies based on their distinct domain organizations. Although many characteristics of the protein family are similar to those of plant species, several features are quite distinct. One such characteristic is the presence of tetratrico peptide repeat (TPR) motifs at the C-terminal ends of these proteins. Another interesting finding is the presence of two E. siliculosus specific conserved motifs leading to novel combination of the NBS domain. The remarkable structural diversity found among these proteins further strengthens the idea that diversifying selection may have played an important role in their evolution.

Page(s): 98-102

Phylogenetic rearrangement of Streptomyces spp. on the basis of internal transcribed spacer (ITS) region using molecular morphometrics approach

Title: Phylogenetic rearrangement of Streptomyces spp. on the basis of internal transcribed spacer (ITS) region using molecular morphometrics approach

Authors: Bhattacharjee, Kaushik; Joshi, S R

Abstract: Streptomycetes, the Gram positive bacteria commonly found in soil, are among the well known antibiotic producers of microbial world. Moreover, Streptomyces spp. produce about 75% of commercially and medically useful antibiotics. They have provided more than half of the naturally occurring antibiotics discovered to date and continue to be screened for useful compounds. Most taxonomic and phylogenetic characterizations of Streptomyces have focused on primary DNA information targeting linear 16S rRNA and ITS sequences. However, RNA secondary structures are particularly not been used for such taxonomic studies, especially the systematics analysis based on “molecular morphometrics information” that are usually not found in the primary sequences. The molecular morphometrics approach has been employed in the present study for comparing the primary and secondary structure information of internal transcribed spacer (ITS) region of Streptomyces spp. using bioinformatics tools. It is an established fact that rRNA structure is highly conserved throughout evolution as most of the folding is functionally important despite primary sequence divergence. The analysis revealed considerable differences between the conventional liner rRNA based phylogeny and the phylogenetic alignment using molecular morphometrics tools.

Page(s): 67-79