A comparative study of three different methods of shoot meristem excision for induction of embryogenic calli in coconut

A protocol was standardized to maximize yields of embryogenic calli from shoot meristem culture of coconut. Three different shoot meristem excision methods were tested viz., excision of shoot meristem aseptically from in vitro germinated embryo after 10-12 days, excision of shoot meristem from in vitro germinated embryo subjected to GA3 treatment for five days and excision of shoot meristem from fresh embryo. The primary calli induction after 30 days of culture incubation for the three treatments were 21%, 27%  and 79% respectively.  Further, the primary calli formed from the shoot meristem excised from fresh embryo gave rise to 56% of embryogenic calli. The calli obtained from the shoot meristem which were excised from in vitro germinated embryo formed less percentage of embryogenic calli because of the presence of cotyledonary tissues which inhibited the multiplication of meristematic tissues. In the case of shoot meristem extracted from GA3-treated embryos, the percentage of non-embryogenic calli was more compared to the shoot meristem excised from fresh embryo. It was observed that the addition of GA3 in the initial stages of culture inhibited the formation of embryogenic calli and favored direct shoot development. Currently, the shoot meristem excised from fresh embryo is being employed for scaling up the planting material production from released varieties of coconut

Local perceptions and adaptation of indigenous communities to climate change: Evidences from High Mountain Pangi valley of Indian Himalayas

58-67The present study was undertaken with aim to understand the perceptions of indigenous communities about climate change pattern and its local impacts on climate variables, seasons, agriculture, biodiversity and adaptive strategies in geographical and technological-isolated Pangi valley situated in Chamba district, Himachal Pradesh. Randomly selected 120 respondents were interviewed and their perceptions were recorded on pre-designed questionnaire. The climate change impacts are experienced in the form of decreased snowfall (98.3%), temperature rise (97.5%), late onset of monsoon (90.8%), decreased rainfall (76.7%), reduced snow-melted water availability (86.7%) and increased drought incidences (85.8%) of over the years. Further, these climatic changes affecting agriculture through early shifts in crop season (80.8%), shorter growing season (91.7%), introduction of fruit and vegetable crops (90.8%), increased incidence of insect-pest (81.2%) and diseases (84.2%) and thereby decline in crop yield (70%). However, majority of the respondents undertaken adaptive strategies such as crop diversification, traditional mixed-cropping, mixed farming, crop rotation and agro-forestry/agro-horticulture systems to cope with climate change but they are either little or unaware of modern farming practices such as snow water/glacier runoff harvesting, agro advisory services, mulching and zero tillage as adaptation strategies

Selective and Irreversible Inhibitors of Mosquito Acetylcholinesterases for Controlling Malaria and Other Mosquito-Borne Diseases

New insecticides are urgently needed because resistance to current insecticides allows resurgence of disease-transmitting mosquitoes while concerns for human toxicity from current compounds are growing. We previously reported the finding of a free cysteine (Cys) residue at the entrance of the active site of acetylcholinesterase (AChE) in some insects but not in mammals, birds, and fish. These insects have two AChE genes (AP and AO), and only AP-AChE carries the Cys residue. Most of these insects are disease vectors such as the African malaria mosquito (Anopheles gambiae sensu stricto) or crop pests such as aphids. Recently we reported a Cys-targeting small molecule that irreversibly inhibited all AChE activity extracted from aphids while an identical exposure caused no effect on the human AChE. Full inhibition of AChE in aphids indicates that AP-AChE contributes most of the enzymatic activity and suggests that the Cys residue might serve as a target for developing better aphicides. It is therefore worth investigating whether the Cys-targeting strategy is applicable to mosquitocides. Herein, we report that, under conditions that spare the human AChE, a methanethiosulfonate-containing molecule at 6 µM irreversibly inhibited 95% of the AChE activity extracted from An. gambiae s. str. and >80% of the activity from the yellow fever mosquito (Aedes aegypti L.) or the northern house mosquito (Culex pipiens L.) that is a vector of St. Louis encephalitis. This type of inhibition is fast (∼30 min) and due to conjugation of the inhibitor to the active-site Cys of mosquito AP-AChE, according to our observed reactivation of the methanethiosulfonate-inhibited AChE by 2-mercaptoethanol. We also note that our sulfhydryl agents partially and irreversibly inhibited the human AChE after prolonged exposure (>4 hr). This slow inhibition is due to partial enzyme denaturation by the inhibitor and/or micelles of the inhibitor, according to our studies using atomic force microscopy, circular dichroism spectroscopy, X-ray crystallography, time-resolved fluorescence spectroscopy, and liquid chromatography triple quadrupole mass spectrometry. These results support our view that the mosquito-specific Cys is a viable target for developing new mosquitocides to control disease vectors and to alleviate resistance problems with reduced toxicity toward non-target species

Chickpea

The narrow genetic base of cultivated chickpea warrants systematic collection, documentation and evaluation of chickpea germplasm and particularly wild Cicer species for effective and efficient use in chickpea breeding programmes. Limiting factors to crop production, possible solutions and ways to overcome them, importance of wild relatives and barriers to alien gene introgression and strategies to overcome them and traits for base broadening have been discussed. It has been clearly demonstrated that resistance to major biotic and abiotic stresses can be successfully introgressed from the primary gene pool comprising progenitor species. However, many desirable traits including high degree of resistance to multiple stresses that are present in the species belonging to secondary and tertiary gene pools can also be introgressed by using special techniques to overcome pre- and post-fertilization barriers. Besides resistance to various biotic and abiotic stresses, the yield QTLs have also been introgressed from wild Cicer species to cultivated varieties. Status and importance of molecular markers, genome mapping and genomic tools for chickpea improvement are elaborated. Because of major genes for various biotic and abiotic stresses, the transfer of agronomically important traits into elite cultivars has been made easy and practical through marker-assisted selection and marker-assisted backcross. The usefulness of molecular markers such as SSR and SNP for the construction of high-density genetic maps of chickpea and for the identification of genes/QTLs for stress resistance, quality and yield contributing traits has also been discussed

Virtual screening and <i>in vitro</i> evaluation of potential growth regulators against somatic embryogenesis receptor-like kinase (SERK) in <i>Cocos nucifera</i> L.

328-340Coconut (Cocos nucifera L.) is one of the most recalcitrant species for in vitro regeneration and the efficiency of induction of somatic embryogenesis in coconut explants has remained low. However, with the advent of the genomics era, more information is now available on the involvement of many genes in the induction of somatic embryogenic pathway. Somatic embryogenesis receptor-like kinases (SERKs), belonging to leucine-rich repeat receptor-like kinase super family are reported to play important roles in the process of somatic embryogenesis. In this study, homology based modeling and molecular dynamics (MD) simulation of a coconut SERK protein (CnSERK) was performed for exploring its structural features, functional characterization of its active sites and binding mechanisms of selected plant hormones and growth regulators by docking studies. The 3-D model for coconut SERK was constructed using structure neighbors of the protein in MODELLER and MD simulation was carried out using GROMACS for 5 ns. Fifteen plant growth regulators were docked with the target SERK protein using GLIDE software. An in vitro study was then carried out to compare the efficiency of three selected chemicals [adenine sulphate, glutathione and 22(S), 23(S)-homobrassinolide] in enhancing somatic embryogenesis from plumular explants of coconut. Plumular explants were from West Coast Tall cultivar of coconut and were inoculated into Eeuwens Y3 media supplemented with various concentrations of each of the three growth regulators. Among the three growth regulators, glutathione (100 µM) gave the best response for induction of both embryogenic calli and somatic embryogenesis. The results of this study might aid in the development of regeneration protocols for in vitro regeneration in coconut

Nanoclay polymer composites loaded with urea and nitrification inhibitors for controlling nitrification in soil

Not AvailableNanoclay polymer composites (NCPCs) were synthesized with partially neutralized acrylic acid and bentonites and loaded with urea and nitrification inhibitors (NIs) to act as a slow release carrier of nitrogen (N). The resulting product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The XRD of NCPCs revealed that the bentonite layers were completely exfoliated and dispersed in the composite after the polymerization. The water absorbency of pure polymer (Acrylic acid + Acrylamide) was 197.53 g g−1 and 137.75 g g−1 by nanocomposite (8% nanobentonite) in distilled water. The nitrification inhibition ability of these NCPCs was evaluated by incubation study for 60 days in laboratory at 28°C and 50% water-holding capacity. The Schiff base -NCPCs were most effective at inhibiting nitrification (30–87%) compared to dicyandiamide and Neem oil. A column study was performed to know the movement of NH4-N and NO3-N at three different depths. Result showed that the Schiff base -NCPC decreased nitrate movement by 78.5% at the depth of 5 cm in soil column. The slow release of nitrogen and good water retention capacity confirmed that these NCPCs can be viably exploited for application in agriculture.Not Availabl

In vitro antimicrobial, antioxidant, haemolytic, thrombolytic activities and phytochemical analysis of Cipadessa bacifera leaves extracts

Objective: To study the leaves of Cipadessa bacifera for their antimicrobial, antioxidant, haemolytic, thrombolytic activities and to perform phytochemical evaluation. Methods: The three extracts (methanol, cyclohexane, chloroform) of Cipadessa bacifera were screened for antimicrobial activity against eight pathogenic microorganisms by well diffusion method. In vitro antioxidant activity of extract was studied using hydrogen peroxide radical scavenging assay. The haemolytic activity was determined using agar diffusion techniques on blood agar plate, thrombolytic activity by clot disruption and phytochemical potential by qualitative analysis. Results: Among the different extracts tested, the methanol extract of leaves showed significant antimicrobial activities. The most susceptible micro-organisms were found to be Gram negative bacteria (Sphingomonas, Klebsiella pneumoniae, Citrobacter), Gram positive bacteria (Enterococcus faecalis) and fungai (Candida albicans). H2O2 scavenging activity of Cipadessa bacifera was found to increase with increasing concentration of the extract. IC50 values of H2O2 scavenging activity was 100.92±0.41 µg/mL which was found in cyclohexane extract.  The haemolytic activity was found to be higher in chloroform extract than methanol, cyclohexane and the methanol extract shows 14.63 % clot lytic whereas standard streptokinase shows 30.86 % clot lytic activity in thrombolytic assay. The phytochemical evaluation indicates the presence of chemical constituents. Conclusions: This study shows that the methanol and chloroform extract of leaves of Cipadessa bacifera has bioactivity but further compound isolation is necessary to confirm the activities of individual compound

Not Available

Not AvailableThe present study was undertaken with aim to understand the perceptions of indigenous communities about climate change pattern and its local impacts on climate variables, seasons, agriculture, biodiversity and adaptive strategies in geographical and technological-isolated Pangi valley situated in Chamba district, Himachal Pradesh. Randomly selected 120 respondents were interviewed and their perceptions were recorded on pre-designed questionnaire. The climate change impacts are experienced in the form of decreased snowfall (98.3%), temperature rise (97.5%), late onset of monsoon (90.8%), decreased rainfall (76.7%), reduced snow-melted water availability (86.7%) and increased drought incidences (85.8%) of over the years. Further, these climatic changes affecting agriculture through early shifts in crop season (80.8%), shorter growing season (91.7%), introduction of fruit and vegetable crops (90.8%), increased incidence of insect-pest (81.2%) and diseases (84.2%) and thereby decline in crop yield (70%). However, majority of the respondents undertaken adaptive strategies such as crop diversification, traditional mixed-cropping, mixed farming, crop rotation and agroforestry/agro-horticulture systems to cope with climate change but they are either little or unaware of modern farming practices such as snow water/glacier runoff harvesting, agro advisory services, mulching and zero tillage as adaptation strategies.Not Availabl