Raies A. Qadri

Current Perspectives on Plant Growth-Promoting Rhizobacteria

The rhizosphere of plant species is an inimitable ecosystem that harbors an extensive range of microbes. Research in the wide areas of rhizosphere biotechnology highlighting new bioinoculants has received ample attention during recent past, and suitable expertises have been developed. However, the global recognition of such technologies by farmers is still overwhelmed with doubts owing to limited shelf-life and efficiency of the products which demonstrate discrepancies. This review illustrates plant growth-promoting rhizobacteria with detailed emphasis on nutrient acquisition and potential roles in conferring tolerance against abiotic stresses. The review demonstrates the recent research in the field of genomic and proteomic analysis, where systematic characterization of potentially effective rhizobacteria is being carried out by screening the extensive bacterial gene pool based on modern molecular tools. The review concludes by emphasizing the efforts made in the proteomics field which could compensate for understanding of prompt evolution in microbe-derived and plant-derived protein and metabolite substitute that activates vulnerability or resistance.

Antibacterial and antioxidant activity of methanol extracts of Crocus sativus L. c.v. Kashmirianus

In this study, we investigated the antibacterial and antioxidant activities of Crocus sativus L. Kashmirianus c.v. extracts (callus and stigmas). Profuse callus was obtained on MS medium enriched with BAP (20 μ M)+NAA (15 μ M) under in vitro conditions from corm slices. Four pathogenic bacterial strains (Staphylococcus aureus CD0001, Escherichia coli CD0006, Pseudomonas aeruginosa CD0023 and Shigella flexneri CD0033) were used for determining the antibacterial activity of extracts. The antioxidant activity was determined by DPPH assay, DNA protection assay, FTC method, TBA assay and lipid peroxidation assay. The methanol stigma extract of saffron was found to be more effective in inhibiting all the pathogenic strains. The stigma extract also showed significant radical scavenging or chelation capacities in four of the methods; however, callus extract exhibited maximum inhibition of peroxy- radicals in lipid peroxidation assay. The protocol for callus production is described. It was concluded that as well as the specific parts of plants displaying diverse pharmacological activities, callus produced under in vitro conditions will assist in enhancing the production of secondary metabolites, which will reduce the pressure on natural saffron.

Tectorigenin ablates the inflammation-induced epithelial–mesenchymal transition in a co-culture model of human lung carcinoma

OBJECTIVES Tumors not only manage to escape from the host immune system, but they effectively contrive to benefit from infiltrating immune cells by modifying their functions so as to create a pro-inflammatory microenvironment favorable for tumor progression and metastasis. In this study we investigated if tectorigenin could suppress lung cancer-induced pro-inflammatory response generated from monocytes. MATERIALS AND METHODS A549:THP1 co-culture model was set-up favoring release of pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α). Effect of tectorigenin on A549 imparted invasive phenotype of A549:THP-1 co-culture was monitored by cytokine release from monocytes, and metastasis/epithelial-mesenchymal transitiom (EMT) in A549 cells. RESULTS In a contact A549:THP1 co-culture model, THP-1 cells were activated by A549 cells favoring secretion of pro-inflammatory cytokines, TNF-α and IL-6. However, priming of A549 cells with tectorigenin for 24h repressed A549 cell-induced secretion of TNF-α and IL-6 by THP-1 cells. Tectorigenin induced change in functional phenotype of A549 cells rendered THP-1 cells non-responsive for the secretion of IL-6 and TNF-α in a contact co-culture setup. Additionally, conditioned media from this non-responsive A549:THP-1 co-culture suppressed metastatic potential of A549 cells as confirmed by the wound healing and transwell migration assays. These finding were further corroborated by decrease in expression of Snail with a concomitant increase in E-cadherin, the two signature markers of EMT. CONCLUSION These results clearly demonstrate the therapeutic potential of tectorigenin to prevent lung cancer elicited inflammatory and pro-metastatic response in monocytes and warrants further investigations to elucidate its mechanism of action.

Screening of beneficial properties of rhizobacteria isolated from Saffron (Crocus sativus L) rhizosphere

Plant growth promoting rhizobacterias (PGPRs) are free living soil bacteria that colonize root surfaces and have the capacity to enhance plant growth directly or indirectly. A total of 23 bacterial strains were isolated from saffron rhizoshere soil during the flowering stage of corms. All these isolates were screened for their plant growth promoting traits like production of IAA, phosphate solubilisation activity and siderophore production. The maximum percentage of the bacterial isolates was of Gram negative rod shaped type. A total of six isolates were capable of showing one or more than one of the activities like IAA production, Siderphore production and phosphate solubilisation activity. The Bacillus subtilis showed highest IAA production of 360 µg/ml while as Pseudomonas ssp., was found to be highly efficient in terms of phosphate solubilisation production (460 µg/ml) and siderophore production (62%). It was concluded from the results that these rhizobacterial strains isolated could be a promising source for plant growth promoting agent in increasing the growth of cormlets vis a vis enhancing the yield of saffron.

Correlation between In Vitro Complement Deposition and Passive Mouse Protection of Anti-Pneumococcal Surface Protein A Monoclonal Antibodies

ABSTRACT The shortcomings of the licensed polysaccharide-based pneumococcal vaccine are driving efforts toward development of a protein-based vaccine that is serotype independent and effective in all age groups. An opsonophagocytic killing assay (OPKA) is used to evaluate the antibody response against polysaccharide-based pneumococcal vaccines. However, the OPKA is not reliable for noncapsular antigens. Thus, there is a need to develop an in vitro surrogate for protection for protein vaccine candidates like pneumococcal surface antigen A (PspA). PspA is a serologically variable cell surface virulence factor. Based on its sequence, PspA has been classified into families 1 (clade 1 and 2), 2 (clades 3, 4 and 5), and 3 (clade 6). Here, we report the characterization of 18 IgG anti-PspA monoclonal antibodies (anti-PspAhkR36A MAbs) generated from mice immunized with heat-killed strain R36A (clade 2). An enzyme-linked immunosorbent assay (ELISA)-based analysis of the reactivity of the MAbs with recombinant PspAs from the 6 clades indicated that they were family 1 specific. This was confirmed by flow cytometry using a hyperimmune serum generated against PspA from R36A. Eight MAbs that bind at least one clade 1- and clade 2-expressing strain were evaluated for complement deposition, bactericidal activity, and passive protection. The anti-PspAhkR36A MAb-dependent deposition of complement on pneumococci showed a positive correlation with passive protection against strain WU2 (r = 0.8783, P = 0.0041). All of our protective MAbs showed bactericidal activity; however, not all MAbs that exhibited bactericidal activity conferred protection in vivo. The protective MAbs described here can be used to identify conserved protection eliciting B cell epitopes for engineering a superior PspA-based vaccine.

Relative expression of CsZCD gene and apocarotenoid biosynthesis during stigma development in Crocus sativus L.

AbstractCrocus sativus is a triploid sterile plant characterized by its red stigmas, which produce significant quantities of carotenoid derivatives formed from the oxidative cleavage of β-carotene and zeaxanthin. The accumulation of three major carotenoid derivatives- crocin, picrocrocin, and safranal- is responsible for the color, bitter taste, and aroma of saffron, which is obtained from the dried stigma of Crocus. Maximum apocarotenoid accumulation occurs during fully developed scarlet stage of stigma development. Zeaxanthin is the precursor for biosynthesis of apocarotenoids. Crocus zeaxanthin 7, 8 (7, 8)-cleavage dioxygenase gene (CsZCD) encodes a chromoplast enzyme that initiates the biogenesis of these apocarotenoids by cleaving zeaxanthin. The Reverse Transcription-PCR analysis revealed that CsZCD gene expression followed different patterns during stigma development. Highest levels of CsZCD gene expression was observed in fully developed scarlet stage of stigma. Real Time PCR analysis showed that there is a sharp increase in gene expression from yellow to orange and orange to scarlet stages of stigma development. Increase in CsZCD gene expression parallels with the apocarotenoid content during the development of stigma, suggesting its regulatory role for apocarotenoid biosynthesis and stigma development in saffron.

Irigenin , a novel lead from Western Himalayan chemiome inhibits Fibronectin-Extra Domain A induced metastasis in Lung cancer cells

Several lines of evidence indicate that Fibronectin Extra Domain A (EDA) promotes metastatic capacity of tumor cells by engaging cell surface α9β1 integrins. This interaction mediated by the C-C loop of EDA activates pro-oncogenic signaling pathways leading to epithelial to mesenchymal transition (EMT) of tumor cells, thus signifying its importance in control of metastatic progression. In this context the present study was designed to explore the active compounds from selected ethno-medicinal plants of western Himalayan region for targeting EDA of Fibronectin in lung carcinoma cells. Structure based informatics for drug designing and screening was employed to generate a lead compound(s) feed that were conformationally and energetically viable. Out of 120 compounds selected, Irigenin showed best binding-affinity with C-C loop of EDA. Irigenin specifically targeted α9β1 and α4β1 integrin binding sites on EDA comprising LEU46, PHE47, PRO48, GLU58, LEU59 and GLN60 in its C-C loop as evaluated by energy decomposition per residue of Irigenin–EDA complex. In-vitro cell motility assays complemented with EDA knock-in and knockdown assays distinctively demonstrated that Irigenin prevents metastatic capacity of lung cancer cells by selectively blocking EDA. The results presented thus project Irigenin as a lead compound to overcome Fibronectin EDA induced metastatic progression in lung carcinoma cells.

Atomic Insight into the Altered O6-Methylguanine-DNA Methyltransferase Protein Architecture in Gastric Cancer.

O6-methylguanine-DNA methyltransferase (MGMT) is one of the major DNA repair protein that counteracts the alkalyting agent-induced DNA damage by replacing O6-methylguanine (mutagenic lesion) back to guanine, eventually suppressing the mismatch errors and double strand crosslinks. Exonic alterations in the form of nucleotide polymorphism may result in altered protein structure that in turn can lead to the loss of function. In the present study, we focused on the population feared for high exposure to alkylating agents owing to their typical and specialized dietary habits. To this end, gastric cancer patients pooled out from the population were selected for the mutational screening of a specific error prone region of MGMT gene. We found that nearly 40% of the studied neoplastic samples harbored missense mutation at codon151 resulting into Serine to Isoleucine variation. This variation resulted in bringing about the structural disorder, subsequently ensuing into a major stoichiometric variance in recognition domain, substrate binding and selectivity loop of the active site of the MGMT protein, as observed under virtual microscope of molecular dynamics simulation (MDS). The atomic insight into MGMT protein by computational approach showed a significant change in the intra molecular hydrogen bond pattern, thus leading to the observed structural anomalies. To further examine the mutational implications on regulatory plugs of MGMT that holds the protein in a DNA-Binding position, a MDS based analysis was carried out on, all known physically interacting amino acids essentially clustered into groups based on their position and function. The results generated by physical-functional clustering of protein indicated that the identified mutation in the vicinity of the active site of MGMT protein causes the local and global destabilization of a protein by either eliminating the stabilizing salt bridges in cluster C3, C4, and C5 or by locally destabilizing the “protein stabilizing hing” mapped on C3-C4 cluster, preceding the active site.

Relative expression of apocarotenoid biosynthetic genes in developing stigmas of Crocus sativus L.

Saffron, the desiccated stigmas of Crocus sativus, is recognized for its attractive color, flavor, and aroma which are due to the accumulation of crocin, picrocrocin, and safranal, respectively. HPLC analysis demonstrated maximum apocarotenoid accumulation during the fully developed scarlet stage of stigma development followed by the orange and yellow stages of stigma development. Reverse Transcription-PCR analysis revealed a concurrent expression pattern of CsZCD and CsLYC genes in a developmental stagespecific manner. However, CsBCH and CsGT2 genes were specifically expressed during the mature, scarlet stage of stigma development. Real-Time PCR analysis showed a sharp increase in gene expression of CsLYC gene during stigma development indicative of its possible regulatory role in apocarotenoid biosynthesis or stigma development. Results suggest that genetic manipulation of this gene can help to improve the quality of stigma in saffron; besides highlighting its potential to monitor stigma development during in vitro experimentation.

Comparative expression analysis of senescence gene CsNAP and B-class floral development gene CsAP3 during different stages of flower development in Saffron ( Crocus sativus L .)

Crocus sativus, a monocot triploid species belonging to the Iridaceae family, is cultivated for its red stigmatic lobes of the carpel that constitute saffron. Flower development has been extensively studied in different plants. Different floral developmental pathways have been deciphered in many plants. In Crocus sativus, flower is the most important part and understanding the pathway underlying the flower development can pave the way for new avenues to improve its productivity and quality. The combination of class A genes (including APETALA1; CsAP1 and APETALA2; CsAP2), class B genes (including APETALA3; CsAP3 and PISTILLATA; CsPI) and class C genes (including AGAMOUS; CsAG) that are active in each whorl, determines the identity of the organs that will later develop in that whorl. CsAP3 is a class B homeotic gene which promotes petal and stamen formation and has a very important role in flower development. It also activates other genes playing pivotal role in flower development. It has been earlier reported that CsAP3 gene has direct role in activation of CsNAP gene which promotes senescence in plants. Present work was focused on study of relative gene expression changes of CsAP3 and CsNAP gene during different stages of flower development. CsAP3 gene expression was found maximum during late-preanthesis stages of stigma development. Expression increases from stage 5 to stage 6 of flower development and then reduces again from stage 6 to stage 7. CsNAP gene had moderate expression during stage 3 to stage 4 transition and its expression increased abruptly from stage 6 to stage 7 of flower development. There is no direct concordance in the expression of CsAP3 and CsNAP gene expression in saffron. We may conclude that some other factor(s) may be responsible for initiation of CsNAP expression and CsAP3 gene may directly/indirectly be involved in regulating the factors responsible for CsNAP activation.