Understanding the interactions among the crop plants, a virus, insect vector whiteflies and their endosymbionts

Interactions among the four biotic agents - the host plants, a virus, insect vector whiteflies and their bacterial endosymbionts was investigated in this study. The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is an important crop pest that is infected by several endosymbiotic bacteria that can play varying roles on their hosts. Both whiteflies and endosymbionts are affected by the host plants they feed on, which in turn affect the fourth agent – the viruses, which are transmitted by the whiteflies. We investigated these interactions on five different host plants – eggplant, tomato, beans, okra and cotton - using a single whitefly species Asia 1 infected with three different bacteria Portiera, Wolbachia and Arsenophonus. B. tabaci Asia 1 transmits the Tomato leaf curl Bangalore virus (ToLCBV) effectively, which was the virus used in the study. We found host plants having a significant impact on whitefly growth and development. Eggplant was most favourable, while okra and tomato were least preferred. The endosymbiont Wolbachia was significantly affected by feeding of B. tabaci on different host plants while Portiera and Arsenophonus were unaffected. When whiteflies fed on ToLCBV-infected tomato plants, the concentration of Arsenophonus increased significantly while other endosymbionts remain unchanged. Understanding these interactions will help in managing both whiteflies and viral diseases

CYCD3 D-type cyclins regulate cambial cell proliferation and secondary growth inArabidopsis

A major proportion of plant biomass is derived from the activity of the cambium, a lateral meristem responsible for vascular tissue formation and radial organ enlargement in a process termed secondary growth. In contrast to our relatively good understanding of the regulation of primary meristems, remarkably little is known concerning the mechanisms controlling secondary growth, particularly how cambial cell divisions are regulated and integrated with vascular differentiation. A genetic loss-of-function approach was used here to reveal a rate-limiting role for the Arabidopsis CYCLIN D3 (CYCD3) subgroup of cell-cycle genes in the control of cambial cell proliferation and secondary growth, providing conclusive evidence of a direct link between the cell cycle and vascular development. It is shown that all three CYCD3 genes are specifically expressed in the cambium throughout vascular development. Analysis of a triple loss-of-function CYCD3 mutant revealed a requirement for CYCD3 in promoting the cambial cell cycle since mutant stems and hypocotyls showed a marked reduction in diameter linked to reduced mitotic activity in the cambium. Conversely, loss of CYCD3 provoked an increase in xylem cell size and the expression of differentiation markers, showing that CYCD3 is required to restrain the differentiation of xylem precursor cells. Together, our data show that tight control of cambial cell division through developmental- and cell type-specific regulation of CYCD3 is required for normal vascular development, constituting part of a novel mechanism controlling organ growth in higher plants

Fitness costs associated with infections of secondary endosymbionts in the cassava whitefly species Bemisia tabaci

We investigated the dual effects of bacterial infections and diseased cassava plants on the fitness and biology of the Bemisia tabaci infesting cassava in Africa. Isofemale B. tabaci colonies of sub-Saharan Africa 1-subgroup 3 (SSA1-SG3), infected with two secondary endosymbiotic bacteria Arsenophonus and Rickettsia (AR+) and those free of AR infections (AR-) were compared for fitness parameters on healthy and East African cassava mosaic virus-Uganda variant (EACMV-UG) infected cassava plants. The whitefly fecundity and nymph development was not affected by bacterial infections, or the infection of cassava by the virus. However, emergence of adults from nymphs was 50% and 17% higher by AR- on healthy and virus-infected plants, respectively than AR+ flies. Development time of adults also was 10 days longer in AR+ than AR-. The whiteflies were further compared for acquisition and retention of East African cassava mosaic virus-Uganda (EACMV-UG). Higher proportion of AR- acquired (91.8%) and retained (87.6%) the virus than AR+ (71.8%, 61.2%, respectively). Similarly, the AR- flies retained higher quantities of virus (~9 folds more) than AR+. These results indicated that bacteria-free whiteflies were superior and better transmitters of EACMV-UG, as they had higher adult emergence, quicker life-cycle and better virus retention abilities than those infected with bacteria

Buccal films: A review of therapy possibilities, treatment plans and appropriate evaluation techniques

Due to apparent greater patient acceptance compared to buccal tablets and enormous therapeutic opportunities compared to traditional oral drug delivery methods, particularly for those who suffer from dysphagia, the potential of the mucoadhesive film technology is difficult to ignore. Despite this, there are currently no authorised mucoadhesive buccal films, and the translation of published literature into the commercial market is essentially non-existent. In order to help this patient-centred dosage form become more widely used, this review aims to give an overview of mucoadhesive buccal film technology and highlight crucial areas on which to concentrate scientific efforts. While discussing the patient-related aspects influencing the utilisation of various dosage forms, a number of indications and development potential were noted. A technical description of the processes used to create these films, including solvent casting, hot melt extrusion, inkjet printing, and three-dimensional printing, was also offered. The utilisation of more than thirty mucoadhesive polymers in film formulations was found, and information about their mucoadhesive properties as well as their inclusion with other essential formulation ingredients was supplied

Fitness costs associated with infections of secondary endosymbionts in the cassava whitefly species Bemisia tabaci

We investigated the dual effects of bacterial infections and diseased cassava plants on the fitness and biology of the Bemisia tabaci infesting cassava in Africa. Isofemale B. tabaci colonies of sub-Saharan Africa 1-subgroup 3 (SSA1-SG3), infected with two secondary endosymbiotic bacteria Arsenophonus and Rickettsia (AR+) and those free of AR infections (AR-) were compared for fitness parameters on healthy and East African cassava mosaic virus-Uganda variant (EACMV-UG) infected cassava plants. The whitefly fecundity and nymph development was not affected by bacterial infections, or the infection of cassava by the virus. However, emergence of adults from nymphs was 50% and 17% higher by AR- on healthy and virus-infected plants, respectively than AR+ flies. Development time of adults also was 10 days longer in AR+ than AR-. The whiteflies were further compared for acquisition and retention of East African cassava mosaic virus-Uganda (EACMV-UG). Higher proportion of AR- acquired (91.8%) and retained (87.6%) the virus than AR+ (71.8%, 61.2%, respectively). Similarly, the AR- flies retained higher quantities of virus (~9 folds more) than AR+. These results indicated that bacteria-free whiteflies were superior and better transmitters of EACMV-UG, as they had higher adult emergence, quicker life-cycle and better virus retention abilities than those infected with bacteria

Characterization of brown streak virus-resistant cassava

Cassava brown streak disease (CBSD) has become a major constraint to cassava production in East and Central Africa. The identification of new sources of CBSD resistance is essential to deploy CBSD mitigation strategies as the disease is progressing westwards to new geographical areas. A stringent infection method based on top cleft grafting combined with precise virus titer quantitation was utilized to screen fourteen cassava cultivars and elite breeding lines. When inoculated with mixed infections of Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), the scions of elite breeding lines KBH 2006/18 and KBH 2006/26 remained symptom-free during a 16-week period of virus graft inoculation, while susceptible varieties displayed typical CBSD infection symptoms at 4 weeks after grafting. The identified CBSD resistance was stable under the co-inoculation of CBSV, UCBSV with cassava geminiviruses (CGMs). Double grafting experiments revealed that transmission of CBSV and UCBSV to CBSD susceptible top scions was delayed when using intermediate scions of elite breeding lines KBH 2006/18 and KBH 2006/26. Nonetheless, comparison of virus systemic movement using scions from KBH2006/18 and a transgenic CBSD resistant 60444 line (60444-Hp9 line) showed that both CBSV and UCBSV move at undetectable levels through the stems. Further, protoplast-based assays of virus titers over time showed that the replication of CBSVs is inhibited in the resistant line KBH2006/18, suggesting that the identified CBSD resistance is at least partially based on inhibition of virus replication. Our molecular characterization of CBSD resistance in cassava offers a robust virus–host system to further investigate the molecular determinants of CBSD resistance

Long Distance Correlations in Molecular Orientations of Liquid Water and Shape Dependant Hydrophobic Force

Liquid water, at ambient conditions, has short-range density correlations which are well known in literature. Surprisingly, large scale molecular dynamics simulations reveal an unusually long-distance correlation in `longitudinal' part of dipole-dipole orientational correlations. It is non-vanishing even at 75 \AA{} and falls-off exponentially with a correlation length of about 24 \AA{} beyond solvation region. Numerical evidence suggests that the long range nature of dipole-dipole correlation is due to underlying fluctuating network of hydrogen-bonds in the liquid phase. This correlation is shown to give a shape dependant attraction between two hydrophobic surfaces at large distances of separation and the range of this attractive force is in agreement with experiments. In addition it is seen that quadrupolar fluctuations vanish within the first solvation peak (3 \AA{})Comment: 11 pages, 3 figure

THIRTY FIVE YEARS OF OPERATIONAL RESEARCH PROJECT FOR DRYLAND AGRICULTURE : ACHIEVEMENTS AND IMPACTS (1976 to 2012)

Not AvailableAgriculture is the backbone of Indian economy and rainfed agro-ecosystem occupies an important place in Indian agriculture, covering 68 per cent of the cultivated area (96 m.ha) supporting 40 per cent human, 60 per cent livestock population and producing 44 per cent of the food requirements thus playing a pivotal role in India’s food security. Five out of ten Agro-Climatic Zones in Karnataka were classified as dry zones covering 63 per cent of the total geographical area and 71 per cent of the net sown area, with substantial contribution to agricultural production from dry lands. About 57 per cent of food grain production in Karnataka comes from rainfed areas while, 97 per cent of total pulses and 80 per cent oilseeds were produced in dry land areas. Research on dryland agriculture in the red soil regions of Karnataka was started in 1970 with the establishment of All India Coordinated Research Project for Dryland Agriculture (AICRPDA) at Gandhi Krishi Vignana Kendra (GKVK), Bangalore,Not Availabl

DEVELOPMENT AND CHARACTERIZATION OF POLYCAPROLACTONE (PCL)/POLY ((R)-3-HYDROXYBUTYRIC ACID) (PHB) BLEND MICROSPHERES FOR TAMOXIFEN DRUG RELESE STUDIES

Objective: The objective of this study was to formulate and evaluate the drug release studies using Poly (ε-caprolactone) (PCL)/and Poly (R)-3-hydroxy butyric acid (PHB) blend microspheres for controlled release of Tamoxifen, an anticancer drug.Methods: Poly (ε-caprolactone), Poly ((R)-3-Hydroxybutyric acid) blend microspheres were prepared through a modified Water/Oil/Water (W/O/W) double emulsion-solvent diffusion method using Dichloromethane as solvent. Tamoxifen (TAM), an anti Cancer drug, was used for encapsulation within PCL/PHB blend microspheres. Morphology, size, encapsulation efficiency and drug release from these microspheres were evaluated by different characterization techniques such as Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry(DSC), Scanning electron microscopy(SEM), X-ray diffraction studies(X-RD) and dissolution test studies respectively.Results: Drug loaded microspheres were analyzed by FT-IR, which indicates the interaction between drug and polymers. DSC thermograms on drug-loaded microspheres confirmed the polymorphism of Tamoxifen and indicated a molecular level dispersion of drug in the microspheres. SEM confirmed the spherical nature and smooth surface of the microspheres produced. X-RD study was performed to understand the crystalline nature of the drug after encapsulation into the microspheres and confirmed the complete dispersion of the drug in the polymer matrix. In-vitro release studies conducted in different pH which indicated a dependence of release rate on the amount of drug loading and the amount of PCL/PHB, but slow release rates were extended up to 12 h. Kinetic analysis of dissolution data showed a good fit in Peppas equation confirming diffusion controlled drug release.Conclusions: The research findings obtained from the studies were found to be satisfactory. It can be concluded that biodegradable polymer blend (PCL/PHB) microspheres can be effectively used for preparation of controlled release matrices. Â

What has changed in the outbreaking populations of the severe crop pest whitefly species in cassava in two decades?

High populations of African cassava whitefly (Bemisia tabaci) have been associated with epidemics of two viral diseases in Eastern Africa. We investigated population dynamics and genetic patterns by comparing whiteflies collected on cassava in 1997, during the first whitefly upsurges in Uganda, with collections made in 2017 from the same locations. Nuclear markers and mtCOI barcoding sequences were used on 662 samples. The composition of the SSA1 population changed significantly over the 20-year period with the SSA1-SG2 percentage increasing from 0.9 to 48.6%. SSA1-SG1 and SSA1-SG2 clearly interbreed, confirming that they are a single biological species called SSA1. The whitefly species composition changed: in 1997, SSA1, SSA2 and B. afer were present; in 2017, no SSA2 was found. These data and those of other publications do not support the ‘invader’ hypothesis. Our evidence shows that no new species or new population were found in 20 years, instead, the distribution of already present genetic clusters composing SSA1 species have changed over time and that this may be in response to several factors including the introduction of new cassava varieties or climate changes. The practical implications are that cassava genotypes possessing both whitefly and disease resistances are needed urgently