Early Establishment of Native Vesicular-Arbuscular Mycorrhizas in Three Vegetable Crops of South India - A Comparative Study

The vesicular-arbuscular mycorrhizal (VAM) status of three vegetable crops viz., tomato, brinjal and chilli was assessed during the initial establishment period in natural field conditions as well as in pot culture using nonsterile soil. The soil had low nutrient status and no manurial application was made during the 60 d course of the study. VAM fungal colonization in the roots was maximum at 45, 50, and 60 d after the respective germination of brinjals, tomato and chilli seeds under field conditions, and on the 60th d in the pot culture experiment. In no case was 100 per cent root colonization obtained. Ascending and descending trends in colonization were observed. In all cases, the original spore count of3.90 (±0.30) g dry soil increased markedly in the rhizosphere soil after plant growth. Spore number was more pronounced in pot than in field culture

Vesicular-Arbuscular Mycorrhizal colonization and growth of tomato (Lycopersicon esculentum) in autoclaved soil

The effect of autoclaving soil an uesicular-arbuscular mycorrhizal (VAAl) Jungal colonization and biomass production of tomato (Lycopersicon esculentum Mill) was assessed in pot experiments under greenhouse conditions. Four treatments were given viz., (1) VAM-free plants in autoclaued soil, (2) VAM plants in autoclaued soil, (3) VAM plants in autoclaved soil amended with VAM-free filtrate of non-autoclaved soil, and (4) VAM plants in non-auloclaved soil. The VAM plants grown in non-autoclaued soil showed the highest root colonization of 87.78% while those under (2) and (3) showed only 55.11 % and 56.94% respectiuely. On the other hand, significantly higher shoot length (105.4 cm2/plant), wtal kaJ area (740.3 cm2/plant) and biomass (8.43 g/plant) were obtained in VAM plants grown in autoclaved soiL VAM-free plants in autaclaved sail had reduced growth. In treatments 3 and 4 plant growth was intermediate. The results indicate that VAM colonization and sporulation were favoured under natural conditions, but VAM plants under autoclaved soil conditions produced maximum growth

Effect of interactions of three growth-promoting microorganisms on VAM colonization, spore density, plant growth and nutrient accumulation in tomato (lycopersicon esculentum) seedlings

Interactions of Azospirillum brasilense and Bacillus megaterium var. phosphaticum and Glomus fasciculatum in the rhizosphere of tomato plants were studied. There was no significant difference in plant growth parameters between YAM-inoculated treatments. Plants inoculated with the phosphobacteria had significantly higher shoot length, which was equivalent to VAM and other VAM + phosphobacteria combinations. Azospirullum or phosphobacteria alone increased plant biomass compared with the uninoculated control. VAM index was significantly reduced with the addition of phosphobacteria. There was no difference in tissue nutrient concentrations between treatments

Cloning, characterization and expression analysis of NBS-LRR-type resistance gene analogues (RGAs) in coconut

Coconut palms are highly susceptible to diseases caused by different pathogens, and replanting with resistant varieties is the best way to manage them. Obtaining a collection of resistance gene analogues (RGAs) is an effective strategy to identify genomic regions linked to disease resistance. We have successfully used a comparative genomics approach to amplify putative RGAs from the coconut root (wilt) disease resistant cultivar Chowghat Green Dwarf (CGD) by using primers designed based on conserved motifs of the NBS-LRR domain of the date palm. The amplified sequences were cloned, sequenced and characterized. The coconut RGAs had high identity to monocot NBS-LRRs. A complete structural analysis and 3-D modeling of the NBS domain of coconut RGA was also undertaken. Real-time quantitative polymerase chain reaction analysis indicated that the isolated coconut NBS-LRR class RGAs was expressed more in root (wilt) disease resistant genotypes than in susceptible ones. This study would provide a base for future efforts to map disease resistant traits in coconut

Lethal Mutagenesis of Poliovirus Mediated by a Mutagenic Pyrimidine Analogue

Lethal mutagenesis is the mechanism of action of ribavirin against poliovirus (PV) and numerous other RNA viruses. However, there is still considerable debate regarding the mechanism of action of ribavirin against a variety of RNA viruses. Here we show by using T7 RNA polymerase mediated production of PV genomic RNA, PV polymerase-catalyzed primer extension and cell-free PV synthesis that a pyrimidine ribonucleoside triphosphate analogue (rPTP) with ambiguous basepairing capacity is an efficient mutagen of the PV genome. The in vitro incorporation properties of rPTP are superior to ribavirin triphosphate. We observed a log-linear relationship between virus titer reduction and the number of rPMP molecules incorporated. A PV genome encoding a high-fidelity polymerase was more sensitive to rPMP incorporation, consistent with diminished mutational robustness of high-fidelity PV. The nucleoside (rP) did not exhibit antiviral activity in cell culture owing to the inability of rP to be converted to rPMP by cellular nucleotide kinases. rP was also a poor substrate for herpes simplex virus thymidine kinase. The block to nucleoside phosphorylation could be bypassed by treatment with the P nucleobase, which exhibited both antiviral activity and mutagenesis, presumably a reflection of rP nucleotide formation by a nucleotide salvage pathway. These studies provide additional support for lethal mutagenesis as an antiviral strategy, suggest that rPMP prodrugs may be highly efficacious antiviral agents, and provide a new tool to determine the sensitivity of RNA virus genomes to mutagenesis as well as interrogation of the impact of mutational load on the population dynamics of these viruses

Lethal Mutagenesis of Picornaviruses with N-6-Modified Purine Nucleoside Analogues

RNA viruses exhibit extraordinarily high mutation rates during genome replication. Nonnatural ribonucleosides that can increase the mutation rate of RNA viruses by acting as ambiguous substrates during replication have been explored as antiviral agents acting through lethal mutagenesis. We have synthesized novel N-6-substituted purine analogues with ambiguous incorporation characteristics due to tautomerization of the nucleobase. The most potent of these analogues reduced the titer of poliovirus (PV) and coxsackievirus (CVB3) over 1,000-fold during a single passage in HeLa cell culture, with an increase in transition mutation frequency up to 65-fold. Kinetic analysis of incorporation by the PV polymerase indicated that these analogues were templated ambiguously with increased efficiency compared to the known mutagenic nucleoside ribavirin. Notably, these nucleosides were not efficient substrates for cellular ribonucleotide reductase in vitro, suggesting that conversion to the deoxyriboucleoside may be hindered, potentially limiting genetic damage to the host cell. Furthermore, a high-fidelity PV variant (G64S) displayed resistance to the antiviral effect and mutagenic potential of these analogues. These purine nucleoside analogues represent promising lead compounds in the development of clinically useful antiviral therapies based on the strategy of lethal mutagenesis

Challenges and opportunities in free-standing supercapacitors research

The design of commercial supercapacitors has remained largely unchanged since the 1970s, comprising powdered electrodes housed in rigid metal cylinders or pouches. To power the next generation of integrated technologies, an evolution in supercapacitor materials and design is needed to create multifunctional materials that allow energy storage while imparting additional material properties (e.g., flexibility and strength). Conductive free-standing electrodes produced from fibers or 3D printed materials offer this opportunity as their intrinsic mechanical properties can be transferred to the supercapacitor. Additionally, their conductive nature allows for the removal of binders, conductive agents, and current collectors from the supercapacitor devices, lowering their economic and environmental cost. In this Perspective, we summarize the recent progress on free-standing supercapacitors from new methods to create free-standing electrodes to novel applications for these devices, together with a detailed discussion and analysis on their electrochemical performance and physicochemical and mechanical properties. Furthermore, the potential directions and prospects of future research in developing free-standing supercapacitors are proposed