Bengyella Louis

Host-Range Dynamics of Cochliobolus lunatus: From a Biocontrol Agent to a Severe Environmental Threat

We undertook an investigation to advance understanding of the host-range dynamics and biocontrol implications of Cochliobolus lunatus in the past decade. Potato (Solanum tuberosum L) farms were routinely surveyed for brown-to-black leaf spot disease caused by C. lunatus. A biphasic gene data set was assembled and databases were mined for reported hosts of C. lunatus in the last decade. The placement of five virulent strains of C. lunatus causing foliar necrosis of potato was studied with microscopic and phylogenetic tools. Analysis of morphology showed intraspecific variations in stromatic tissues among the virulent strains causing foliar necrosis of potato. A maximum likelihood inference based on GPDH locus separated C. lunatus strains into subclusters and revealed the emergence of unclustered strains. The evolving nutritional requirement of C. lunatus in the last decade is exhibited by the invasion of vertebrates, invertebrates, dicots, and monocots. Our results contribute towards a better understanding of the host-range dynamics of C. lunatus and provide useful implications on the threat posed to the environment when C. lunatus is used as a mycoherbicide.

Grappling the high altitude for safe edible bamboo shoots with rich nutritional attributes and escaping cyanogenic toxicity.

Consumption of bamboo species with high level of total cyanogenic content (TCC) in Asia by many ethnic groups is significantly associated with food poisoning and occasionally Konzo (a neurological disorder). Adequate characterization of edible bamboo species with low level of TCC and high nutritious attributes is required for consumers safety as well as for the conservation of the gene pool. Here, we employed morphological descriptors, atomic absorption spectrophotometer, RAPD, and trnL-F intergenic spacer to characterize 15 indigenous edible bamboo species of north-east India. The study indicates that morphologically and genetically evolved edible bamboo species having large and robust bamboo-shoot texture and growing at low altitude contain high level of TCC, low antioxidant properties, and low levels of beneficial macronutrients and micronutrients. Importantly, Dendrocalamus species are shown to be rich in TCC irrespective of the growing altitude while Bambusa species are found to have moderate level of TCC. The findings clearly demonstrated that Chimonobambusa callosa growing at high altitude represents safe edible bamboo species with nutritious attributes.

An Effective Protocol for Micropropagation of Edible Bamboo Species (Bambusa tulda and Melocanna baccifera) through Nodal Culture

High demand for edible bamboo shoots of Bambusa tulda and Melocanna baccifera in many Asian ethnic groups has led to the need for developing intensive bamboo farming. To achieve this, in vitro regeneration of bamboo plantlets is needed due to the long and irregular bamboo flowering cycle and scarcity of bamboo seeds. An effective protocol for plantlets regeneration in B. tulda and M. baccifera from nodal explants following validation of the species using the sequence of trnL-F intergenic spacer region is described. Effective axillary bud breaking was achieved at 3 mg/L of 6-benzylaminopurine (BAP) in MS medium. Importantly, combining 2 mg/L of kinetin (Kn) with 3 mg/L of BAP produced a synergistic effect for shoot multiplication in B. tulda and M. baccifera. Under optimized conditions in half-strength MS medium supplemented with 3 mg/L of indole-3-butyric acid (IBA), 10 mg/L of coumarin, and 3% sucrose, profuse production of dark-brown rhizome in B. tulda and abundant rooting (81.67%, P < 0.05, F = 15.46) for M. baccifera within 30 days were achieved. The established protocol and the validation of the reported species at the molecular level will be of help to stakeholders in edible bamboo trade to conserve gene-pool and increase productivity.

Biotrophic interaction of Sporisorium scitamineum on a new host--Saccharum spontaneum.

Sporisorium scitamineum is a biotrophic smut fungus harbored inside the smut gall on the top internodal region of Saccharum spontaneum, a wild relative of sugarcane (Saccharum officinarum). The interactions of spined conidia of S. scitamineum with S. spontaneum were examined during the different stages of plant growth starting from the bud stage to the decaying stage. The spores in the soil from the polyetic inocula grew into confined epidermal cells of the buds and finally sporulated in the topmost internodal region. Hyphae invasion of the plant tissues were restricted to the point of infection. Culms of infected plants in late October sporulated, notably; hyphal sporulation produced shorter hyphal stolons. Remarkably, the nodal regions of infected plants had no spores and fragmented hyphae. On the basis of microscopic analyses, hyphae and spores were absent in all internodes above the ground till the topmost smut gall region. This result indicated that, S. scitamineum undergoes tissue-confined invasion of S. spontaneum. By associating culture medium method with polymerase chain reaction (PCR) on plant portions void of smut gall, S. scitamineum was not detected, indicating that colonization was not systemic. It was observed that the biotrophic interaction resulted in structural reorganization in the restricted region of infection forming erect cylindrical structure, in which the fungus was sandwiched between the central stalk and sheath, and possibly played a key role in preventing inflorescence. Comparatively, a significant difference in the rate of teliospores germination between reference Ustilago esculenta (26.6%, P<0.05) and S. scitamineum (62.9%, P<0.05) at 20° C was observed. This study also provides insights on the effect of different temperature regimes on the germination of S. scitamineum teliospores in vitro.

Current trends in outwitting resistance development in Candida infections through photodynamic and short peptide therapies: a strategic-shift from conventional antifungal agents.

Abstract Disequilibrium in the human debilitated immune system favors proliferation of invasive Candida species, a major therapeutic challenge due to development of resistance to several conventional antifungal agents (CAA) worldwide. Multiple mutations observed at specific loci that are targets for CAA are recognized as sources of drug resistance. This has prompted a shift from CAA, to diverse combination therapies, photodynamic and short peptide therapies capable of triggering specific apoptotic reactions within candidal cells. In this review, new designs and combination of short peptide (SP) with CAA as well as current application of photodynamic inactivation (PDI) against Candida species geared at generating reactive species of oxygen (ROS) and nitrogen (RNS) are discussed. It is observed that oxidative and nitrosative stresses provides a superior broad candidacidal effects for eradication of drug-resistant Candida species. The mechanism and limitations in these strategic approaches over CAA is also discussed.

Switching between Heat Shock Proteins and Cold Inducible Proteins under Temperature Fluctuation in Solanum tuberosum L. Cultivars in In Vivo Condition

Cross-talking between heat shock proteins (HSPs) and cold inducible proteins (CIPs) subsequent to combinational mild heat (35°C) and cold (8°C) stress was investigated in vivo for four cultivars of Solanum tuberosum L. viz. Kufri Pukhraj (PO), Kufri Jyoti (GS), Kufri Ashoka (KF) and Kufri Chandramukhi (CM) in the order of their decreasing thermotolerance, to understand how this economic crop adapts to extreme temperature fluctuation. We showed a time-course differential genotypic expression pattern for HSPs at 35°C for 10h and CIPs at 8°C for 12h time-lapse. Remarkably, we noted the disappearance of a housekeeping protein (HKP) of about 19.8KD at 2h, 35°C in GS absent in CM, KF and PO; but strongly expressed as CIPs at 8°C for all the cultivars. Furthermore, heat-stress led to an outstanding transient induction of HSP95.9, HSP83.6, HSP78.7, HSP70.7, HSP66.0, HSP54.1, HSP48.6, HSP43, sHSP38.3, sHSP35.3, sHSP29, sHSP22.5, sHSP17.8 and sHSP9.5 in GS at 6h, while HKP58.7, HKP55.5 and HKP43.7 were stably overexpressed in CM, KF and PO. Temperature switching from 35°C to 8°C upregulated HKP43.4, HKP54.6, CIP14.1 and HKP19.9 for all the cultivars. The recovery process 24h subsequent to this archetype switching was governed by overexpression of small(s)HSPs of about 25.4KD-14.1KD, HKP58.7 and HKP43.5 for all cultivars. Results suggest crosstalk protection for this paradigm-shift in temperature is chiefly conferred by isoforms of constitutively expressed HKPs, CIP19.9 and CIP14.1 in S. tuberosum L. Explicitly, this differential proteome change within 22h signify HKPs may not participate in thermotolerance as HSPs, but participate in cold acclimation as CIPs, recovery as sHSPs and even switch-off during heat-stress in some cultivars as depicted in GS. Research Article British Biotechnology Journal, 1(3): 101-112, 2011 102

Confined enzymatic activity of S. scitamineum and U. esculenta at the Smut Gallduring Infection

We aimed to evaluate the enzymatic abilities of U. esculenta and S. scitamineum to degrade cellulose, pectin and lignin and explain the possible confinement of the smut - fungi in the smut-gall. S. scitamineum and U. esculenta were isolated from the smut gall of S. spontaneum and Z. latifolia plants, respectively. The teliospores were inoculated into a culture flask containing various concentrations (3%-10%) of pure cellulose powder to check the degradation ability of the fungi. The fungi were sub-cultured onto modified Czapek Dox Agar (CDA) supplemented with 0.3% carboxy methyl cellulose (CMC) followed by Gram’s Iodine test to determine the relative cellulolytic activity index (RCAI). Extracellular proteins were harvested and profiled by SDS-PAGE and subsequently zymography was carried out with regular 0.1% substrate infiltration to determine cellulolytic, pectinolytic and laccase activities. The fungi were capable of producing cellulase and pectinase but lacked the laccase enzyme required to degrade the lignin, perhaps as an essential evolutionary requirement for the completion of their life cycle in the host. Importantly, the lack of laccase activity by U. esculenta and S. scitamineum could partially explain why the fungal colonization remains localized in the topmost part of S. spontaneum and Z. latifolia.