Exogenous dsRNA-mediated field protection against Pigeonpea sterility mosaic emaravirus

Journal of Plant Biochemistry and Biotechnology - Pigeonpea sterility mosaic emaraviruses (PPSMVs) cause sterility mosaic disease in pigeonpea which significantly reduce the crop yield. Currently...     

Plant growth-promoting rhizobacterial mediated protection of tomato in the field against cucumber mosaic virus and its vector Aphis gossypii

Studies evaluated the effect of rhizobacterial interactions on a virus under natural conditions of high levels of vector–virus pressure on tomato plants. The rhizobacterium Bacillus subtilis was isolated from the rhizosphere soil of healthy tomato plant and the strain is referred to as BS3A25. The BS3A25 treatment of seeds significantly enhanced tomato seed germination rates to 99% compared to the control seeds at 78%. Combination of both seed and foliar spray treatments significantly protected the plants from cucumber mosaic virus (CMV) and also significantly enhanced plant growth. Strain BS3A25 possesses many positive traits such as phosphate solubilization ability, ACC utilization as the sole source of nitrogen and production of significantly higher concentrations of indoles, IAA and the cytokinin, IPA. The growth parameters of the aphid Aphis gossypii Glover such as development time, time from birth to adult (t_D) and prereproduction time (t_d) were longer, whereas the relative growth rate (RGR) and intrinsic rate of natural increase (r_m), were found to be lower in the BS3A25 supernatant treatment compared to commercial insecticide imidacloprid treatment. Noticeably, the present study recorded higher activity of phenylalanine ammonia lyase, Peroxidase, total phenols, and polyphenol oxidase in plants treated with BS3A25 generating the speculation of induced defence responses in plants. The results obtained in the field study showed that treatment by BS3A25 formulation as seed and foliar treatment proved highly effective in reducing the aphid population and CMV incidence compared to a commercially available insecticide. The highest cost:benefit ratio (1:2.5) was obtained in BS3A25 formulation treatment followed by imidacloprid (1:2.0) and control plants (1:1.4). These constitute an important step towards the production of BS3A25 as a commercially-available induced resistance agent.     

Coat protein gene-mediated protection in Lactuca sativa against lettuce mosaic potyvirus strains

Lettuce mosaic potyvirus (LMV) can be very destructive on lettuce crops worldwide. The LMV strain 0 (LMV-0) coat protein (CP) gene was engineered for expression in plants. It was introduced into three susceptible cultivars of Lactuca sativa using an improved procedure for transformation and regeneration of lettuce, by co-cultivation of leaf explants with Agrobacterium tumefaciens. Several transformants accumulated detectable levels of LMV CP. The R1 progeny of twelve R0 transformants (four plants per cultivar) with T-DNA integration at one single locus, was studied for protection against LMV. The progeny from five R0 transformants showed resistance to LMV-0, with the effectiveness of resistance depending on the development stage of the plants at the time of inoculation. The R1 and R2 progeny from one of these R0 transformants, Cocarde-9a, were more extensively analysed. The homozygous but not the hemizygous R1 plants displayed protection to LMV-0. The R2 progeny from one homozygous R1 plant were shown to be resistant to infection by LMV-0 and other LMV strains. As previously observed in other cases of potyvirus sequence-mediated protection, a phenomenon of recovery was observed in some plants, as well as complete resistance. However, this recovery phenotype was not always maintained, as opposed to the previous described cases, leading to a late progression of viral infection.     

Biochemical changes in pigeonpea (Cajanus cajan (L.) Millsp.) leaves in relation to resistance against sterility mosaic disease

Changes in different biochemical parameters like total phenolic content, protein pattern, polyphenol oxidase, peroxidase and isozymes of peroxidase were compared in sterility mosaic resistant (Hy3C) and susceptible (Type-21) pigeonpea varieties at different growth stages both under inoculated and uninoculated conditions. Resistant variety was characterized by the presence of specific isoperoxidase and proteins but only little difference was recorded between resistant and susceptible variety with respect to preformed or induced total phenolics and peroxidase activity. The activity of polyphenol oxidase increased substantially in susceptible variety following infection. Role of these changes is discussed in relation to disease resistance. Research Publication no. 3949 G.B. Pant University of Agriculture and Technology, Pantnagar, India. Deceased.     

Positive and negative sense coat protein gene-mediated protection against poplar mosaic carlavirus in Nicotiana benthamiana

Plants of Nicotiana benthamiana were transformed with four constructs based on the coat protein gene of a poplar mosaic carlavirus (PMV) isolate from the UK. The four constructs were: the capsid protein coding sequence plus a portion of the adjacent sequence encoding a protein with a molecular mass of 14 kDa (CP14k); the capsid protein coding sequence in the positive sense (CPP); a mutated capsid protein coding sequence (CPM) and the capsid protein coding sequence in the negative sense (CPN). Forty-one regenerated plants, after selection for their kanamycin resistance, were confirmed by PCR to contain the appropriate sequences. Virus coat protein was detected in small amounts in 50% of the plants transformed with the CP14k or CPP constructs. Primary transformants showed a range of reactions to challenge with two isolates of PMV. These varied from apparently no infection in inoculated or in later-formed young leaves, as assessed by ELISA, to typical systemic symptoms associated with large amounts of serologically detected virus. There was no correlation between the level of protection against virus infection and the observed accumulation of transgene protein product. Plants were protected whether transformed with the coat protein coding sequence in the positive or negative sense.     

黄瓜花叶病毒基因组不同部分及卫星RNA介导的对植株的保护及其作用机理

根据病原物介导的对自身抗性的理论,大量开展了将CMV基因组的单个或多个片断转入植物体内的研究,从而使该植株能够抵抗或延迟受CMV的侵染,CP,RP,MP基因是CMV基因组的重要组成部分,用来转化植株取得了不同程度的抗性效果,另外有些CMV株中存在着起致弱作用的卫星RNA,直接对植株接种含卫星RNA的CMV弱毒或用卫星RNA的cDNA转化植株都会减轻CMV强毒对该植株的侵害,CMV基因组不同组分进入植物体内后,它们对植株产生保护作用的机理不同,文中分别加以阐述。     

Extremely low-frequency magnetic field exposure and protection against UV-induced death in chicken embryos

We report on a study where 4-day old chicken embryos from different flocks were pre-treated with 50 Hz magnetic fields (MF) prior to a 60-min UV-C exposure (1.7 mW/cm(2)) to investigate the possible protective effect of MF exposure on UV-induced embryo death. Different flux densities (0.010, 0.025, 0.050, 0.10, and 0.20 mT), field directions (vertical and horizontal), as well as MF exposure times (10, 20, and 60 min) were employed. We did not find any significant effects by MF exposure, irrespective of exposure time, flux density, or field direction on the survival of embryos. Neither could we find any flock dependency on sensitivity to MF exposure.     

Resistance of transgenic tomato to cucumber mosaic cucumovirus under field conditions

Since the summer of 1993, transgenic tomato plants expressing the coat protein (CP) genes of cucumber mosaic cucumovirus have been tested under field conditions to assess the level of resistance and agronomic performance. Trials were performed in different areas in Italy and the target virus in the majority of tests was spread naturally by the indigenous aphid populations. Twenty-three homozygous lines of variety UC82B, transformed to contain four different CP genes of CMV, were evaluated. The lines were preselected for CP expression, single gene copy, and virus resistance in growth chamber experiments. In general, CMV resistance was confirmed under field conditions though resistance in the field was less effective than what was observed in growth chamber experiments. The resistance observed in multi-year and multi-location experiments is of commercial value for several of the most resistant lines. Engineered resistance upon transfer to Italian varieties by breeding or direct transformation will be used in tomato production in Italy or elsewhere. This revised version was published online in June 2006 with corrections to the Cover Date.     

Correction to: Role of sialylated glycans on bovine lactoferrin against influenza virus

Glycoconjugate Journal -     

Normal adaptations to exercise despite protection against oxidative stress

It has been reported that supplementation with the antioxidant vitamins C and E prevents the adaptive increases in mitochondrial biogenesis and GLUT4 expression induced by endurance exercise. We reevaluated the effects of these antioxidants on the adaptive responses of rat skeletal muscle to swimming in a short-term study consisting of 9 days of vitamins C and E with exercise during the last 3 days and a longer-term study consisting of 8 wk of antioxidant vitamins with exercise during the last 3 wk. The rats in the antioxidant groups were given 750 mg·kg body wt(-1)·day(-1) vitamin C and 150 mg·kg body wt(-1)·day(-1) vitamin E. In rats euthanized immediately after exercise, plasma TBARs were elevated in the control rats but not in the antioxidant-supplemented rats, providing evidence for an antioxidant effect. In rats euthanized 18 h after exercise there were large increases in insulin responsiveness of glucose transport in epitrochlearis muscles mediated by an approximately twofold increase in GLUT4 expression in both the short- and long-term treatment groups. The protein levels of a number of mitochondrial marker enzymes were also increased about twofold. Superoxide dismutases (SOD) 1 and 2 were increased about twofold in triceps muscle after 3 days of exercise, but only SOD2 was increased after 3 wk of exercise. There were no differences in the magnitudes of any of these adaptive responses between the control and antioxidant groups. These results show that very large doses of antioxidant vitamins do not prevent the exercise-induced adaptive responses of muscle mitochondria, GLUT4, and insulin action to exercise and have no effect on the level of these proteins in sedentary rats.     

Transgenes in plants: protection against viruses and insects

Protective transgenes introduced into plants can be classified as directed against insects, fungi, bacteria or viruses. Mechanisms by which they protect plants in some cases are relatively simple and understood while in most cases they present only the field of rapidly progressing investigations. A brief review of the recent concepts of the resistance induced in plants against viruses by virus-derived transgenes is presented with emphasising the RNA mediated resistance. The RNA mediated resistance seems to operate in Nicotiana benthamiana plants transformed in our laboratory with cDNA of the PPV CP gene: both translatable and untranslatable versions of the cDNA made the transformed plants resistant against PPV. The resistant plants contained more than one copy of the transgene. To protect against insects plants were in our laboratory transformed with potato proteinase inhibitor II gene (PPI-II). The PPI-II gene expressed in model plants inhibited trypsin activity to an expected level.     

Exogenous GSH protection during hypoxia-reoxygenation of the isolated rat heart: impact of hypoxia duration

The objective of this study was to determine the interaction between duration of myocardial hypoxia and presence of exogenous glutathione (GSH) on functional recovery upon subsequent reoxygenation. Isolated perfused rat hearts were subjected to 20, 30, 40, or 50 min hypoxia (HYP), which resulted in a progressive decline in the amount of contractile recovery (% of normoxic rate-pressure product (RPP) and developed pressure) during 30 min reoxygenation. Supplementation with 5 mM GSH throughout normoxia, hypoxia, and reoxygenation significantly improved contractile recovery during reoxygenation after 20 and 30 min hypoxia (p < 0.05), but had no effect after longer durations of hypoxia when contractile recovery was typically below 40% of RPP and significant areas of no-reflow were observed. ECG analysis revealed that GSH shifted the bell-shaped curve for reperfusion ventricular fibrillation to the right resulting in attenuated fibrillation after 20 and 30 min hypoxia then increased incidences after 40 min when Control hearts were slow to resume electrical activity. ECG conduction velocity was well preserved in all hearts after 20 and 30 min hypoxia, but GSH administration significantly attenuated the decline that occurred with longer durations. GSH supplementation did not attenuate the 35% decline in intracellular thiols during 30 min of hypoxia. When 5 mM GSH was added only during 40 min of hypoxia, RPP recovery after reoxygenation was improved compared to unsupplemented Controls (73% vs. 55% of pre-hypoxia value, p < 0.05). Administration of GSH only during reoxygenation following 40 min of hypoxia did not alter RPP recovery compared to Control hearts. We conclude that cardioprotection by exogenous GSH is dependent on the duration of hypoxia and the functional parameter being evaluated. It is not due to an enhancement of intracellular GSH suggesting that exogenous GSH acts extracellularly to protect sarcolemmal proteins against thiol oxidation during the phase of hypoxia when oxidative stress is a major contributor to cardiac dysfunction. Furthermore, if enough damage accrues during oxygen deprivation, supplementing with GSH during reoxygenation will not impact recovery.     

Biorational management tactics to select against triazine-resistant Amaranthus hybridus: a field trial

1. The individual and joint effectiveness of two biorational tactics (crop interference and exploitation of negative cross-resistance to certain herbicides) in the management of triazine-resistant Amaranthus hybridus L. (smooth pigweed) were estimated. Biorational tactics exploit biological idiosyncracies of resistant (R) genotypes to maximize fitness cost(s) of resistance. We quantified selection against triazine resistance by relative performance comparisons between lines having comparable nuclear genomes but either resistant or susceptible cytoplasm. Increasing soybean density by reducing row spacing (from 76 cm to 25 cm) did not significantly increase the fitness cost of resistance.
2. Low doses of bentazon (100 and 300 g active ingredient ha^–1) did strongly increase the cost of resistance. Over 2 years, the mean relative performance of R genotypes in bentazon treatments was 0·40, compared to 0·60 in the absence of bentazon. Therefore, use of bentazon in soybean production has the potential to delay evolution of triazine resistance in maize–soybean rotations using triazines.
3. There was no consistent indication that increased soybean density and bentazon herbicide could act synergistically to increase costs of triazine resistance in Amaranthus hybridus . Nor were differences in response to biorational tactics evident between the two populations of origin (Maryland and Virginia, USA) from which experimental lines were derived.
4. Effects of the biorational tactics differed markedly between years, highlighting that resistance management depending primarily on these tactics would have widely variable results. Use of such tactics is likely to be most effective in the context of diversified weed management.     

Correction to: An empirical test of bet-hedging polyandry hypothesis in the field cricket Gryllus bimaculatus

Journal of Ethology -