FUNCTIONAL ANALYSIS OF MEDICINAL PLANTS USING SYSTEMS BIOLOGY APPROACHES

Plant derived medicine is an important source of life saving drugs, but the genome information of most important medicinal plants is still unavailable. The need of the hour is to identify more functional genes and enzymes that control secondary metabolite production in medical plants, develop new methods for systematics, engineer resistance to number of biotic and abiotic stresses, and develop new conservation strategies, more genomics, proteomics and metabolomics information needs to be produced. In this review, a brief overview of various omic technologies and its applications to medicinal and aromatic plants are discussed.Â

SCREENING OF ENDOPHYTIC FUNGI FOR THEIR ABILITY TO PRODUCE EXTRACELLULARCELLULASES

Objective: Screening endophytic isolates from woody perennial medicinal plants of Western Ghats for production of extracellular cellulasesMethods: Endophytes were isolated using normal microbiological methods and their colonization frequency and dominance were calculated using statistical methods. Efficiency of growth on complex cellulosic substrates was evaluated on media supplemented with specific substrates. Enzyme assays with identified endophytic fungi were carried from their secretome.Results:Forty endophytic fungal isolates were obtained using standard isolation methods from different medicinal plants from a biodiversity hotspot in the Western Ghats region of Karnataka, India. The isolated endophytic fungi were then identified based on their morphological characters. The percentage of dominant endophytes (ð·) was calculated based on the colonization frequency. Among the isolated fungi, F. solani and Talaromyces sp. was found to be highest, at5.5 and 5.6 respectively. Each of the identified fungi grown on CMC and seven among the 40 isolates were found to grow luxuriantly as measured by radial growth. The identities of these fungi were morphologically reconfirmed and were completely carbon drained by growing them on a low nutrient medium. These fungi were later evaluated for their growth on avicel and microcrystalline cellulose. Fusarium solani and Tarlaromyces sp. were significantly better in their growth when compared to other endoophytes tested. Further, the cellulosome complex of enzymes were analysed in the secretome of Fusarium solani and Talaromyces sp. Total filter paper activity of Fusarium solani was found to be FPU/ml, 76 FPU/ml and 70 FPU/ml at 24, 48 and 72 hours respectively. Similarly, Filter paper activity of Talaromyces sp. was found to be 89, 86 and 78 FPU/ml at 24h, 48h and 72h respectively. Endogluconase activity of Fusarium solani was found to be 63 CMCase, 60and 61 CMCase at 24, 48 and 72hours of incubation respectively, which was greater than Talaromyces sp. Similarly, Exogluconase and Beta-glucosidase activities were also found to be high in Talomyces sp. when compared to Fusarium solani at all the time intervals tested.Conclusion:The results from the present study reveals that Fusarium sSolani and Talaromyces sp.are extremely potent producers of cellulases and can thus be used for eco-friendly and economic hydrolysis of biomass for biofuel purposes. Â

Comparative system biology for understanding desiccation tolerance in Sellaginella sps

International audienc

Comparative system biology for understanding desiccation tolerance in Sellaginella sps

International audienc

Vegetative desiccation tolerance in Eragrostiella brachyphylla: biochemical and physiological responses

International audienceEragrostiella brachyphylla is an angiosperm desiccation-tolerant resurrection plant, which can survive during desiccation in the air-dry state and recover completely on availability of water. The present study was conducted to understand the vegetative desiccation tolerance of Eragrostiella brachyphylla by evaluating its ability to recover the physiological, biochemical and morphological functions post desiccation. In order to understand the responses of Eragrostiella brachyphylla to desiccation and subsequent rehydration experiments were conducted in the hydrated state (HS), desiccated state (DS) and rehydrated state (RS). Scanning electron microscopy revealed significant changes between the three stages in the internal ultra-structures of leaves and stems. Compared to the other states, photosynthetic parameters such as chlorophyll a, chlorophyll b, total chlorophylland total carotenoid contents decreased significantly in the desiccated state. Superoxide radical (O2 À) content also increased, resulting in an oxidative burst during desiccation. Consequently, antioxidant enzymes such as catalase (CAT) superoxide dismutase (SOD) peroxidase (APX) and glutathione reductase (GR) activities were found to be significantly elevated in the desiccated state to avoid oxidative damage. Increased malondialdehyde (MDA) content and relative electrolyte leakage (REL) during desiccation provide evidence for membrane damage and loss of cell-wall integrity. During desiccation, the contents of osmolytes represented by sucrose and proline were found to increase to maintain cell structure integrity. After rehydration, all physiological, biochemical and morphological properties remain unchanged or slightly changed when compared to the hydrated state. Hence, we believe that these unique adaptations contribute to the remarkable desiccation-tolerance property of this plant

Physiological and biochemical responses involved in vegetative desiccation tolerance of resurrection plant Selaginella brachystachya

International audienceThe vegetative desiccation tolerance of Selaginella brachystachya has been evaluated for its ability to revive from a desiccation (air dry) state and start normal functioning when rehydrated. In this study, S. brachystachya was identified by DNA barcoding. Experiments were conducted using the detached hydrated, desiccated and rehydrated fronds under laboratory conditions to understand the mechanism of revival upon the water availability. Scanning Electron Microscope images during desiccation showed closed stomata and inside curled leaves. Chlorophyll concentration decreased by 1.1 fold in desiccated state and recovered completely upon rehydration. However, the total carotenoid content decreased 4.5 fold while the anthocyanin concentration increased 5.98 fold and the CO2 exchange rate became negative during desiccation. Lipid peroxidation and superoxide radical production were enhanced during desiccation by 68.32 and 73.4%, respectively. Relative electrolyte leakage was found to be minimal during desiccation. Activities of antioxidant enzymes, namely peroxidase (158.33%), glutathione reductase (107.70%), catalase (92.95%) and superoxide dismutase (184.70%) were found to be higher in the desiccated state. The proline concentration increased by 1.4 fold, starch concentration decreased 3.9 fold and sucrose content increased 2.8 fold during desiccation. Upon rehydration, S. brachystachya recovered its original morphology, physiological and biochemical functions. Our results demonstrate that S. brachystachya minimizes desiccation stress through a range of morphological, physiological and biochemical mechanisms. These results provide useful insights into desiccation tolerance mechanisms for potential utilization in enhancing stress tolerance in crop plants

Desiccation tolerance in plants: Structural characterization of the cell wall hemicellulosic polysaccharides in three Selaginella species

International audienceDrought-induced dehydration of vegetative tissues in lycopods affects growth and survival. Different species of Selaginella have evolved a series of specialized mechanisms to tolerate desiccation in vegetative tissues in response to water stress. In the present study, we report on the structural characterization of the leaf cell wall of the desiccation-tolerant species S. involvens and two desiccation-sensitive species, namely S. kraussiana and S. moellendorffii. Isolated cell walls from hydrated and desiccated leaves of each species were fractionated and the resulting oligosaccharide fragments were analyzed to determine their structural features. Our results demonstrate that desiccation induces substantial modifications in the cell wall composition and structure. Altogether, these data highlight the fact that structural remodeling of cell wall hemicellulosic polysaccharides including XXXG-rich xyloglucan, arabinoxylan and acetylated galactomannan is an important process in order to mitigate desiccation stress in Selaginella