Crude oligosaccharides mediated resistance and histo-chemical changes in Capsicum annuum against anthracnose disease caused by Colletotrichum capsici

Enhancing the host resistance using biotic elicitors is one of the eco-friendly approaches developed for plant disease management. The Crude Oligosaccharides (CO) extracted from Colletotrichum capsici (Syd.) Butler & Bisby was evaluated for their efficiency to elicit resistance in chilli against anthracnose disease. Among the different concentrations tested, CO treatment at 2.5 mg/ml concentration for 3 h duration significantly enhanced seed germination (90.5%) and seedling vigor (986.7), compared to control which offered 78% of seed germination and 712.5 of seedling vigor. Application of CO at 2.5 mg/ml concentration also reduced the disease severity with a highest anthracnose disease protection of 68% under greenhouse conditions and enhanced the vegetative growth parameters compared to control. The induction of resistance was evident with higher expression of primary defense responses like hypersensitive response, deposition of lignin, callose, hydrogen peroxide and phenol when compared to control plants. There was a one fold increase in defense enzyme activities phenylalanine ammonia lyase, peroxidase, polyphenol oxidase, and lipoxygenase in crude oligosaccharide-treated inoculated seedlings when compared to susceptible inoculated seedlings which were similar to that of resistant inoculated seedlings where a maximum of 1.5-fold increase in enzyme activity was observed.     

Azide-resistant mutants ofAzorhizobium caulinodans with enhanced symbiotic effectiveness

Azide-resistant mutants ofAzorhizobium caulinodans strains Sb3, S78, SrR13 and SrS8 were isolated and screened for nitrate reductase activity. Selected nitrate reductase negative mutants were inoculated onSesbania bispinosa andS. rostrata under sterile conditions in chillum jars to study their symbiotic behavior. Azide-resistant mutants exhibited either similar or higher symbiotic effectiveness than the parent strain after 30 d of plant growth. Nodule mass, nitrogenase activity and uptake hydrogenase activity of the mutants varied depending on the host as well as on the plant growth stage. In comparison to wild-type parent strains, four azide-resistant mutants, Sb3Az18, S78Az21, SrR13Az17 and SrS8Az6 showed significant increase in nodulation and nitrogen fixation as well as shoot dry mass of the inoculated plants.     

Symbiotic effectiveness of spontaneous antibiotic-resistant mutants of Rhizobium sp. Cicer nodulating chickpea (Cicer arietinum)

Spontaneous streptomycin-resistant mutants were isolated from two fast growing gum-producing strains Ca85 and Ca401 and from two moderately growing strains Ca181 and Ca534 of Rhizobium sp. Cicer. The nodulation ability and symbiotic effectiveness of the mutants relative to parent strains were evaluated on chickpea (Cicer arietinum) grown in sterilized chillum jars. Some mutants of strains Ca85 and Ca401 showed Nod phenotype whereas some mutants of strains Ca181 and Ca534 showed Nod(+) fix(-) phenotype. Other mutants also showed decreased nodule number and reduction in nitrogenase activity as well as in shoot dry weight as compared to inoculation with parental strains. The results showed that acquisition of streptomycin resistance in Rhizobium sp. Cicer strains is associated with decreased symbiotic effectiveness in chickpea, suggesting that antibiotic-resistant mutants first should be analyzed for symbiotic effectiveness before using these mutants for ecological studies or nodulation competitiveness.     

Competition among<Emphasis Type="Italic">Bradyrhizobium</Emphasis> strains for nodulation of green gram (<Emphasis Type="Italic">Vigna radiata</Emphasis>): Use of dark-nodule strain

The competitiveness of dual-strain inoculum of Bradyrhizobium strains S24 and GR4 was demonstrated for nodulation of green gram (Vigna radiata). Strain S24 formed pink nodules, GR4 produced visually distinguishable dark-brown nodules. When a mixture of these Bradyrhizobium strains was applied as inoculum, nodules of both pink and dark-brown types were formed on the same root. The strain GR4, which was less competitive than strain S24, was mutagenized with N-methyl-N'-nitro-N-nitrosoguanidine to obtain pigment-diverse mutants and six selected mutants were screened for symbiotic parameters. One mutant produced pink nodules and appreciably increased plant dry mass. The competitive ability of this mutant lacking brown pigment was compared with that of strain S24 by using antibiotic resistance markers; it showed increased nodulation competitiveness than its parent strain GR4. The dark-brown nodule-phenotype could be useful in evaluating nodulation competitiveness of "cowpea miscellany" bradyrhizobia in soil where dark-brown nodule-forming strains are not indigenous.     

Anisotropic stretch-induced hypertrophy in neonatal ventricular myocytes micropatterned on deformable elastomers

Because cell shape and alignment, cell-matrix adhesion, and cell-cell contact can all affect growth, and because mechanical strains in vivo are multiaxial and anisotropic, we developed an in vitro system for engineering aligned, rod-shaped, neonatal cardiac myocyte cultures. Photolithographic and microfluidic techniques were used to micropattern extracellular matrices in parallel lines on deformable silicone elastomers. Confluent, elongated, aligned myocytes were produced by varying the micropattern line width and collagen density. An elliptical cell stretcher applied 2:1 anisotropic strain statically to the elastic substrate, with the axis of greatest stretch (10%) either parallel or transverse to the myofibrils. After 24 h, the principal strain parallel to myocytes did not significantly alter myofibril accumulation or expression of atrial natriuretic factor (ANF), connexin-43 (Cx-43), or N-cadherin (by indirect immunofluorescent antibody labeling and immunoblotting) compared with unstretched controls. In contrast, 10% transverse principal strain resulted in continuous staining of actin filaments (rhodamine phalloidin); increased immunofluorescent labeling of ANF, Cx-43, and N-cadherin; and upregulation of protein signal intensity by western blotting. By using microfabrication and microfluidics to control cell shape and alignment on an elastic substrate, we found greater effects for transverse than for longitudinal stretch in regulating sarcomere organization, hypertrophy, and cell-to-cell junctions.     

Effects of nerve graft on nitric oxide synthase, NAD(P)H oxidase, and antioxidant enzymes in chronic spinal cord injury

Oxidative stress and nitrosative stress play important roles in the pathogenesis of secondary spinal cord injury. Recently, we demonstrated that peripheral nerve grafts (PNG) with acidic fibroblast growth factor (aFGF) partially restore hind limb locomotion in adult rats with completely transected spinal cords. This study investigated the protein abundances of the superoxide (O2*)-generating enzyme nicotinamide adenine dinucleotide (phosphate) oxidase (NAD(P)H oxidase; gp91phox subunit), nitric oxide synthases (NOS), antioxidant enzymes, superoxide dismutases (Cu Zn SOD, Mn SOD), catalase, and glutathione peroxidase (GPX) as well as nitrotyrosine in the spinal cord tissue 4 months after spinal cord transection in rats with and without PNG and aFGF. The protein abundances of the gp91phox subunit of NAD(P)H oxidase, Mn SOD, catalase, GPX, eNOS, and nitrotyrosine were significantly upregulated, whereas Cu Zn SOD and nNOS were unchanged in the injury group compared to the sham controls. The nerve graft with aFGF treated group showed significantly better hind limb locomotion recovery than the injury group. Although the protein abundances of gp91phox, nitrotyrosine, and Cu Zn SOD were similar in the treated group (nerve graft with aFGF) compared to the injury group, Mn SOD, GPX, catalase, and eNOS protein abundances were significantly higher, whereas nNOS was markedly lower in the treated group. We conclude that the combination of nerve graft and aFGF enhances the local antioxidant defense system after spinal cord transection in rats.     

Analogue-resistant mutants of Azotobacter chroococcum derepressed for nitrogenase activity and early ammonia excretion having potential as inoculants for cereal crops

Spontaneous mutants resistant to methionine sulfoximine (Msx), methyl alanine (Mal) and methyl ammonium chloride (Mac) were derived from A. chroococcum strain A103. Msx and Mal-resistant mutants expressed 1.73 to 10.98% of the fully derepressed nitrogenase activity when grown in Burk's medium containing ammonium acetate. Mac-resistant mutants did not express nitrogenase activity in ammonium acetate supplemented medium. The mutants excreted ammonia even after 2 days of growth and some mutants excreted more ammonia as compared to the parent. Selected mutants were inoculated on wheat (Triticum aestivum) and barley (Hordeum vulgare) under field conditions. Majority of the derepressed mutants increased grain yield of wheat and barley varying from 1.2 to 33.3%. However, host-dependent effects on grain yield were observed with different mutants. Two mutants, Mal 27 and Mac 19 showed significant increase in grain yields of both the crops. The results suggest that metabolic analogue-resistant mutants of Azotobacter have potential for use as a biofertilizer for cereal crops.     

Physiological traits associated with heat tolerance in bread wheat (Triticum aestivum L.)

Field experiments for evaluating heat tolerance-related physiological traits were conducted for two consecutive years using a mapping population of recombinant inbred lines (RILs) from the cross RAJ4014/WH730. Chlorophyll content (Chl) and chlorophyll fluorescence (CFL) were recorded under timely sown (TS) and late sown (LS) conditions. Late sowing exposes the terminal stage of plants to high temperature stress. Pooled analysis showed that CFL and Chl differed significantly under TS and LS conditions. The mean value of CFL (Fv/Fm) and Chl under both timely and late sown conditions were used as physiological traits for association with markers. Regression analysis revealed significant association of microsatellite markers viz., Xpsp3094 and Xgwm131 with coefficients of determination (R²) values for CFL (Fv/Fm) and Chl as 12 and 8 %, respectively. The correlation between thousand grain weight (TGW) with Chl and CFL were 14 and 7 % and correlation between grain wt./spike with Chl and CFL were 15 and 8 %, respectively. The genotypes showing tolerance to terminal heat stress as manifested by low heat susceptibility index (HSI = 0.43) for thousand grain weight, were also found having very low Chl, HSI (−0.52). These results suggest that these physiological traits may be used as a secondary character for screening heat-tolerant genotypes.     

Increasement of Heterologous Expression of Recombinant Vit v 1 in Pichia pastoris KM71 by Nonionic Detergents as a Cost-effective Approach

Applied Biochemistry and Microbiology - Vit v 1 as a lipid-transfer protein is a major allergen of grapes (Vitis vinifera) that elicits food allergy in many patients in Iran. Todays, recombinant...     

The use of stable carbon isotopes to decipher global change effects on soil organic carbon: present status,limitations, and future prospects

Major global change factors, including carbon dioxide (CO₂) fertilization, warming, change in precipitation, nitrogen deposition, and land-use change have the potential to significantly affect future stocks of soil organic carbon (SOC). These factors, individually or by interacting with each other, can also trigger positive or negative feedback to the processes affecting the rate of SOC formation or loss. Despite rapid progress in the understanding of carbon (C) cycling processes in the last few decades, much uncertainty remains in our ability to precisely forecast potential changes in SOC stocks in the rapidly changing future world. Stable C isotopes have been extensively used in natural observational studies as well as in laboratory and field experiments that manipulate CO₂ concentration, temperature, moisture, nitrogen fertilization, and vegetation type to understand the complex interactions and feedbacks that result from changing climate, plants and their herbivores, as well as soil microorganisms. Newly developed tools such as compound-specific isotope analysis, nano-SIMS (secondary ion mass spectroscopy), and stable isotope probing (SIP) permit isotope tracing in a specific ecosystem pool into specific C compounds and processes, thus providing in-depth insights into many processes affecting C biogeochemistry. The recent availability of affordable and reliable field-deployable optical isotope monitoring devices has provided researchers with a new set of tools for continuously tracking the ¹³C-CO₂ fluxes at the ecosystem level, enabling deeper insights into C biogeochemistry under changing environmental conditions. Despite these great strides, there is a scarcity of review studies that have comprehensively examined the use of C isotopes in studying SOC responses under global change factors. This review highlights recent progress in understanding the effect of major global change factors on SOC fluxes and stocks using selected examples covering scales from plant rhizospheres to geographic regions. Moreover, we discuss the strengths and limitations of current approaches and recent scientific advancements to highlight the new prospects evolving from the exceptional temporal and spatial resolution of stable isotope analysis in studying how global change affects SOC. Finally, we suggest that studies using stable C isotopes are well-poised to focus on identifying how dominant SOC cycling processes respond to environment-specific limiting factors and any thresholds and tipping points that define those relationships.