Cotton Leaf Curl Virus: lonic Status of Leaves and Symptom Development

In the present study, the relationship between the nutritional status of leaves and the development of symptoms of cotton leaf curl virus (CLCuV) in two cotton (Gossypium hirsutum L.) cultivars (i.e. CIM-240 and S-12) was investigated. The incidence of disease attack was found to be 100% in the S-12 cultivar and 16% in the CIM-240 cultivar. Geminivirus particles in infected leaves were confirmed by transmission electron microscope examination of highly specific geminivirus coat protein antisera-treated cell sap. The CLCuV impaired the accumulation of different nutrients in both cultivars. A marked decrease in the accumulation of Ca2+ and K+ was observed in infected leaves. However, the disease had no effect on leaf concentrations of Na+, N, and P. It was observed that the curling of leaf margins in CLCuV-infected plants was associated with the leaf Ca2+ content; leaf curling was severe in plants with a significant reduction in Ca2+ content.Moreover, leaf K+ content was found to be associated with resistance/susceptibility to CLCuV infection.     

First Report of bla CTX-M-15-Type ESBL-Producing Klebsiella pneumoniae in Wild Migratory Birds in Pakistan

EcoHealth - We investigated wild migratory birds faecal swabs for extended-spectrum β-lactamases-producing Klebsiella pneumoniae (ESBL-K. pneumoniae) from wetland habitats in Pakistan. ESBL-K....     

Biochemical and molecular identification of Xanthomonas translucens pv. undulosa causing bacterial leaf streak of wheat in Punjab,Pakistan

Xanthomonas translucens pv. undulosa, (Xtu.), causal agent of Bacterial leaf streak (BLS) of wheat, was characterised through pathogencity, hypersensitivity, biochemical and molecular assays. Fifty symptomatic leaves of wheat were collected from eight agro-ecological zones of Punjab out of which 25 were isolated and purified. Maximum incidence and severity in Faisalabad were followed by Multan and Rahim Yar Khan. The pathogen isolated from diseased leaves was identified on the basis of colonies pattern, colour, biochemical and pathogencity test as X. translucens pv. undulosa and confirmed its pathogencity through pathogencity test. For molecular characterization, the bacterial 16S–23S rDNA spacer fragments were amplified by PCR with conserved primers (C1 and C2) and then in combination with specific primers (T1 & T2). 300?bp product amplified by C1 and C2 primer pair confirmed the presence of Xanthomonas, while specific primers T1 and T2 amplified a product of 200?bp, confirmed the presence of X. translucens pv. undulosa. This work will be quite helpful for wheat pathologist and breeders for future management strategy for this disease.     

Silicon amendment to rice plants contributes to reduced feeding in a phloem‐sucking insect through modulation of callose deposition

Silicon (Si) uptake by Poaceae plants has beneficial effects on herbivore defense. Increased plant physical barrier and altered herbivorous feeding behaviors are documented to reduce herbivorous arthropod feeding and contribute to enhanced plant defense. Here, we show that Si amendment to rice (Oryza sativa) plants contributes to reduced feeding in a phloem feeder, the brown planthopper (Nilaparvata lugens, BPH), through modulation of callose deposition. We associated the temporal dynamics of BPH feeding with callose deposition on sieve plates and further with callose synthase and hydrolase gene expression in plants amended with Si. Biological assays revealed that BPH feeding was lower in Si‐amended than in nonamended plants in the early stages post‐BPH infestation. Histological observation showed that BPH infestation triggered fast and strong callose deposition in Si‐amended plants compared with nonamended plants. Analysis using qRT‐PCR revealed that expression of the callose synthase gene OsGSL1 was up‐regulated more and that the callose hydrolase (β‐1,3‐glucanase) gene Gns5 was up‐regulated less in Si‐amended than in nonamended plants during the initial stages of BPH infestation. These dynamic expression levels of OsGSL1 and Gns5 in response to BPH infestation correspond to callose deposition patterns in Si‐amended versus nonamended plants. It is demonstrated here that BPH infestation triggers differential gene expression associated with callose synthesis and hydrolysis in Si‐amended and nonamended rice plants, which allows callose to be deposited more on sieve tubes and sieve tube occlusions to be maintained more thus contributing to reduced BPH feeding on Si‐amended plants.     

Allelopathic suppression of wheat and mustard byRumex dentatus ssp.klotzschianus

Laboratory studies were conducted to see the allelopathic suppression of wheat and mustard byRumex dentatus ssp.klotzschianus (Meissn) Rech. It was observed that aqueous extracts, rain leachates and litter from dried and fresh shoot and roots invariably inhibited the germination and seedling growth of both the crop species. Soil collected from beneathRumex dentatus also proved harmful for the germination and seedling growth. It is suggested thatRumex dentatus ssp.klotzschianus exhibits allelopathy against wheat and mustard.     

Antimutagenic activity of methanolic extracts of four ayurvedic medicinal plants

Methanolic extracts of Acorus calamus (Rhizome), Hemidesmus indicus (Stem), Holarrhena antidysenterica (Bark) and Plumbago zeylanica (Root), were tested for their antimutagenic potential. These extracts, at tested concentrations, showed no sign of mutagenicity to Salmonella typhimurium tester strains. The extracts of the plants exhibited varying level of antimutagenicity. At a dose of 100 microg/plate, the extracts exhibited the inhibition of His+ revertants from 18.51% to 82.66% against direct acting mutagens, methyl methanesulphonate (MMS) and sodium azide (NaN3) induced mutagenicity in Salmonella tester strains TA 97a, TA 100, TA 102 and TA 104. However, at lower concentrations (25 and 50 mcirog/plate) of the plant extracts, a decrease in antimutagenic activity was recorded. Dose dependent antimutagenic activity of the extracts is also evident from linear regression analysis of the data. The over all antimutagenic potential of above four extracts was found to be in order of A. calamus > H. indicus > H. antidysenterica > P. zeylanica. Further, total phenolic content of these extracts did not correlate with its antimutagenic activity in A. calamus and P. zeylanica.     

Mobilization and Acquisition of Sparingly Soluble P-Sources by Brassica Cultivars under P-Starved Environment I. Differential Growth Response,P-Efficiency Characteristics and P-Remobilization

Phosphorus （P） starvation is highly notorious for limiting plant growth around the globe. To combat P-starvation, plants constantly sense the changes in their environment, and elicit an elegant myriad of plastic responses and rescue strategies to enhance P-solublization and acquisition from bound soil P-forms. Relative growth responses, P-solublization and P- acquisition ability of 14 diverse Brassica cultivars grown with sparingly soluble P-sources （Rock-P （RP） and Ca3（PO4）2 （TCP）） were evaluated in a solution culture experiment. Cultivars showed considerable genetic diversity in terms of biomass accumulation, concentration and contents of P and Ca in shoots and roots, P-stress factor （PSF） and P use efficiency. Cultivars showed variable P-stress tolerance, and cultivars depicting low PSF and high P-efficiency values were better adaptable to P-starvation. In experiment 2, after initial feeding on optimum nutrition for 12 d after transplanting （DAT）, class-I （low P-tolerant （Oscar and Con-II）） and class-II （low P-sensitive （Gold Rush and RL-18）） cultivars were exposed to P-free environment for 25 d. All of the cultivars remobilized P from above ground parts to their roots during growth in P-free environment, the magnitude of which was variable in tested cultivars. P-concentrations （[P]s） at 37 DAT were higher in developing compared with developed leaves. Translocation of absorbed P from metabolically inactive to active sites in P- stressed plants may have helped class-I cultivars to establish a better rooting system, which provided a basis for enhanced P-utilization efficiency （PUE） and tolerance against P-stress. By supplying TCP and RP spatially separated from other nutrients in split root study, class-I cultivars were still able to mobilize RP and TCP more efficiently compared with class-II cultivars. To compare the growth behavior under P-stress, cultivars were grown in pots for 41 d after sowing, using a soil low in P （NaHCO3-extractable P = 3.97 mg/kg, M     

Mobilization and Acquisition of Sparingly Soluble P-Sources by Brassica Cultivars under P-Starved Environment II. Rhizospheric pH changes,Redesigned Root Architecture and Pi-Uptake Kinetics

Non-mycorrhizal Brassica does not produce specialized root structures such as cluster or dauciform roots but is an effective user of P compared with other crops. In addition to P-uptake, utilization and remobilization activity, acquisition of orthophosphate （Pi） from extracellular sparingly P-sources or unavailable bound P-forms can be enhanced by biochemical rescue mechanisms such copious H＋-efflux and/or carboxylates exudation into rhizosphere by roots via plasmalemma H＋ ATPase and anion channels triggered by P-starvation. To visualize the dissolution of sparingly soluble Ca-phosphate （Ca-P）, newly formed Ca-P was suspended in agar containing other essential nutrients. With NH4＋ applied as the N source, the precipitate dissolved in the root vicinity can be ascribed to rhizosphere acidification, whereas no dissolution occurred with nitrate nutrition. To observe in situ rhizospheric pH changes, images were recorded after embedding the roots in agar containing bromocresol purple as a pH indicator. P-tolerant cultivar showed a greater decrease in pH than the sensitive cultivar in the culture media （the appearance of typical patterns of various colors of pH indicator in the root vicinity）, and at stress P-level this acidification was more prominent. In experiment 2, low P-tolerant class-I cultivars （Oscar and Con-II） showed a greater decrease in solution media pH than low P-sensitive class-II （Gold Rush and RL-18） cultivars, and P-contents of the cultivars was inversely related to decrease in culture media pH. To elucidate P-stress- induced remodeling and redesigning in a root architectural system, cultivars were grown in rhizoboxes in experiment 3. The elongation rates of primary roots increased as P-supply increased, but the elongation rates of the branched zones of primary roots decreased. The length of the lateral roots and topological index values increased when cultivars were exposed to a P-stress environment. To elucidate Pi-uptake kinetics, parameters related to P influx： maximal     

Ethnobotanical studies of plants of Charkotli Hills, Batkhela District, Malakand, Pakistan

A survey was conducted with the aim to document the indigenous information of Charkotli Hills, Batkhela District, Malakand, Pakistan. The area has rich vegetation and a high potential for ethnobotanical utilization. Information was collected on various traditional uses of 100 plants distributed over 49 families, of which 43 families were of dicot, 2 of monocot, 2 of pteridophyta, and 1 of gymnosperms. Most plants have more than one local use. Sixty-six plants were found to be medicinal species, 21 fruit and edible seed species, 11 furniture species, 18 fodder or forage species, 12 vegetable species, 12 fuel species, 11 thatching and building species, 5 hedge or fencing species, 5 timber wood species, 5 poisonous plants, 3 species used in ketchup, 2 fixed oil yielding species, 2 miswak species, 2 species for making sticks for cattle and defense purposes, 2 species cultivated for ornamental purposes, 2 species used as mehindi by girls, 1 irritant species, 1 species for the making of Salai (a little stick for applying ‘surma’ to the eyes), 1 species for tanning, 1 species used as refresher in milk pots, 1 species giving gum used as chewing gum, and 1 species used as insect repellent. The area is under heavy pressure of deforestation and overgrazing, which have reduced the regeneration of woody plants. Proper ecological management is required to protect the wildlife and ethnobotanical resources for the coming generations.     

Natural agents: cellular and molecular mechanisms of photoprotection

The skin is the largest organ of the body that produces a flexible and self-repairing barrier and protects the body from most common potentially harmful physical, environmental, and biological insults. Solar ultraviolet (UV) radiation is one of the major environmental insults to the skin and causes multi-tiered cellular and molecular events eventually leading to skin cancer. The past decade has seen a surge in the incidence of skin cancer due to changes in life style patterns that have led to a significant increase in the amount of UV radiation that people receive. Reducing excessive exposure to UV radiation is desirable; nevertheless this approach is not easy to implement. Therefore, there is an urgent need to develop novel strategies to reduce the adverse biological effects of UV radiation on the skin. A wide variety of natural agents have been reported to possess substantial skin photoprotective effects. Numerous preclinical and clinical studies have elucidated that natural agents act by several cellular and molecular mechanisms to delay or prevent skin cancer. In this review article, we have summarized and discussed some of the selected natural agents for skin photoprotection.