Mutant crtRB1 gene negates the unfavourable effects of opaque2 gene on germination and seed vigour among shrunken2-based biofortified sweet corn genotypes.

Sweet corn is one of the most popular vegetables worldwide. However, traditional shrunken2 (sh2 )-based sweet corn varieties are poor in nutritional quality. Here, we analysed the effect of (1) ß-carotene hydroxylase1 (crtRB1 ), (2) opaque2 (o2 ) and (3) o2+crtRB1 genes on nutritional quality, germination, seed vigour and physico-biochemical traits in a set of 27 biofortified sh2 -based sweet corn inbreds. The biofortified sweet corn inbreds recorded significantly higher concentrations of proA (16.47µg g-1 ), lysine (0.36%) and tryptophan (0.09%) over original inbreds (proA: 3.14µg g-1 , lysine: 0.18%, tryptophan: 0.04%). The crtRB1 -based inbreds had the lowest electrical conductivity (EC), whereas o2 -based inbreds possessed the highest EC. The o2 +crtRB1 -based inbreds showed similar EC to the original inbreds. Interestingly, o2 -based inbreds also had the lowest germination and seed vigour compared to original inbreds, whereas crtRB1 and o2 +crtRB1 introgressed sweet corn inbreds showed similar germination and seed vigour traits to their original versions. This suggested that the negative effect of o2 on germination, seed vigour and EC is nullified by crtRB1 in the double mutant sweet corn. Overall, o2 +crtRB1 -based sweet corn inbreds were found the most desirable over crtRB1 - and o2 -based inbreds alone.

A DNA aptamer-based assay for the detection of soluble ST2, a prognostic biomarker for monitoring heart failure.

Heart failure (HF) is emerging as a leading cause of death worldwide. Estimation of BNP levels is a routine diagnosis in these patients. However, in patients having high body-mass index (BMI), renal disease or in geriatric patients, BNP level is reported to be noisy and leads to incongruous conclusion. Thus, for better risk stratification among heart failure patients, it is imperative to look for a superior biomarker. In recent times, sST2 has shown promise as a biomarker. Identifying such biomarkers in peripheral blood of HF patients, need an affine and selective molecular recognition element. Thus, in the current study an aptamer (sS9_P) against sST2 was identified from an aptamer library. Systematic Evolution of Ligands through Exponential enrichment (SELEX) derived aptamer evinced role of its primer binding domains in maintaining its selectivity. This aptamer candidate demonstrated dissociation constant (Kd) in low nanomolar range, and the Limit of Detection (LOD) was ~4 ng. Circular dichroism confirms the formation of complex stem-loop like structure. The well characterized sS9_P aptamer was used in an Aptamer Linked Immobilized Sorbent Assay (ALISA) to detect sST2 level in patients' serum (n = 99). Aptamer sS9_P has shown significant discrimination to differentiate HF patients and healthy volunteers with a reasonable specificity (~83 %) with a modest sensitivity of ~64 %. While sST-2 antibody has shown poor specificity of ~44% but good sensitivity (~87%). The insight obtained from this study indicates that a combination of aptamer and antibody-based assay can be used to design a point-of-care assay for the rapid detection of HF patients in emergency settings.

Controlling the Morphological Features, Aspect Ratio and Emission Patterns of Supramolecular Copolymers by Restricted Dimensional Growth.

One of the bottlenecks associated with supramolecular polymerization of functional π-systems is the spontaneous assembly of monomers leading to one- or two-dimensional (1D or 2D) polymers without control over chain length and optical properties. In the case of supramolecular copolymerization of monomers that are structurally too diverse, preferential self-sorting occurs unless they are closely interacting donor-acceptor pairs. Herein, it is established that the spontaneous 1D polymerization of a phenyleneethynylene (PE) derivative and the 2D polymerization of a Bodipy derivative (BODIPY) can be controlled by copolymerizing them in different ratios, leading to unusual spindle-shaped structures with controlled aspect ratio, as evident by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM) studies. For example, when the content of BODIPY is 50 % in the BODIPY-PE mixture, the 1D polymerization of PE is significantly restricted to form elongated spindle-like structures having an aspect ratio of 4-6. The addition of 75 % of BODIPY to PE resulted in circular spindles having an aspect ratio of 1-2.5, thereby completely restricting the 1D polymerization of PE monomers. Moreover, the resultant supramolecular copolymers exhibited morphology and aspect ratio dependent emission features as observed by the time-resolved emission studies.

Hydrogen Peroxide and GA3 Levels Regulate the High Night Temperature Response in Pistils of Wheat (Triticum aestivum L.).

High night temperature (HNT) impairs crop productivity through the reproductive failure of gametes (pollen and pistil). Though female gametophyte (pistil) is an equal partner in the seed-set, the knowledge of the antioxidant system(s) and hormonal control of HNT tolerance or susceptibility of pistils is limited and lacking. The objectives of this study were to determine the antioxidant mechanism for homeostatic control of free radicals, and the involvement of abscisic acid (ABA) and gibberellic acid (GA3) in HNT stress protection in the wheat pistils of contrasting wheat genotypes. We hypothesized that HNT tolerance is attributed to the homeostatic control of reactive oxygen species (ROS) and hormonal readjustment in pistils of the tolerant genotype. The ears of two contrasting wheat genotypes-HD 2329 (susceptible) and Raj 3765 (tolerant) were subjected to two HNTs (+5 °C and +8 °C) over ambient, in the absence and presence of dimethylthiourea (DMTU), a chemical trap of hydrogen peroxide (H2O2). Results showed that HNTs significantly increased ROS in pistils of susceptible genotype HD 2329 to a relatively greater extent compared to tolerant genotype Raj 3765. The response was similar in the presence or absence of DMTU, but the H2O2 values were lower in the presence of DMTU. The ROS levels were balanced by increased activity of peroxidase under HNT to a greater extent in the tolerant genotype. Cytosolic glyceraldehyde-3-phosphate dehydrogenase (GAPC) activity was inversely related to H2O2 production within a critical range in Raj 3765, indicating its modulation by H2O2 levels as no change was observed at the transcriptional level. The hormonal status showed increased ABA and decreased GA3 contents with increasing temperature. Our study elucidates the role of H2O2 and GA3 in stress tolerance of pistils of tolerant genotype where GAPC acts as a ROS sensor due to H2O2-mediated decrease in its activity.

Structural and Functional Characterization of Rv0792c from Mycobacterium tuberculosis: Identifying Small Molecule Inhibitor against HutC Protein.

In order to adapt in host tissues, microbial pathogens regulate their gene expression through a variety of transcription factors. Here, we have functionally characterized Rv0792c, a HutC homolog from Mycobacterium tuberculosis. In comparison to the parental strain, a strain of M. tuberculosis with a Rv0792c mutant was compromised for survival upon exposure to oxidative stress and infection in guinea pigs. RNA sequencing analysis revealed that Rv0792c regulates the expression of genes involved in stress adaptation and virulence of M. tuberculosis. Solution small-angle X-ray scattering (SAXS) data-steered model building confirmed that the C-terminal region plays a pivotal role in dimer formation. Systematic evolution of ligands by exponential enrichment (SELEX) resulted in the identification of single-strand DNA (ssDNA) aptamers that can be used as a tool to identify small-molecule inhibitors targeting Rv0792c. Using SELEX and SAXS data-based modeling, we identified residues essential for Rv0792c's aptamer binding activity. In this study, we also identified I-OMe-Tyrphostin as an inhibitor of Rv0792c's aptamer and DNA binding activity. The identified small molecule reduced the growth of intracellular M. tuberculosis in macrophages. The present study thus provides a detailed shape-function characterization of a HutC family of transcription factor from M. tuberculosis. IMPORTANCE Prokaryotes encode a large number of GntR family transcription factors that are involved in various fundamental biological processes, including stress adaptation and pathogenesis. Here, we investigated the structural and functional role of Rv0792c, a HutC homolog from M. tuberculosis. We demonstrated that Rv0792c is essential for M. tuberculosis to adapt to oxidative stress and establish disease in guinea pigs. Using a systematic evolution of ligands by exponential enrichment (SELEX) approach, we identified ssDNA aptamers from a random ssDNA library that bound to Rv0792c protein. These aptamers were thoroughly characterized using biochemical and biophysical assays. Using SAXS, we determined the structural model of Rv0792c in both the presence and absence of the aptamers. Further, using a combination of SELEX and SAXS methodologies, we identified I-OMe-Tyrphostin as a potential inhibitor of Rv0792c. Here we provide a detailed functional characterization of a transcription factor belonging to the HutC family from M. tuberculosis.

Immunogenicity and protective efficacy of tuzin protein as a vaccine candidate in Leishmania donovani-infected BALB/c mice.

Visceral leishmaniasis (VL) is referred to as the most severe and fatal type of leishmaniasis basically caused by Leishmania donovani and L. infantum. The most effective method for preventing the spread of the disease is vaccination. Till today, there is no promising licensed vaccination for human VL. Hence, investigation for vaccines is necessary to enrich the therapeutic repertoire against leishmaniasis. Tuzin is a rare trans-membrane protein that has been reported in Trypanosoma cruzi with unknown function. However, tuzin is not characterized in Leishmania parasites. In this study, we for the first time demonstrated that tuzin protein was expressed in both stages (promastigote and amastigote) of L. donovani parasites. In-silico studies revealed that tuzin has potent antigenic properties. Therefore, we analyzed the immunogenicity of tuzin protein and immune response in BALB/c mice challenged with the L. donovani parasite. We observed that tuzin-vaccinated mice have significantly reduced parasite burden in the spleen and liver compared with the control. The number of granulomas in the liver was also significantly decreased compared with the control groups. We further measured the IgG2a antibody level, a marker of Th1 immune response in VL, which was significantly higher in the serum of immunized mice when compared with the control. Splenocytes stimulated with soluble Leishmania antigen (SLA) displayed a significant increase in NO and ROS levels compared with the control groups. Tuzin-immunized and parasite-challenged mice exhibit a notable rise in the IFN-γ/IL-10 ratio by significantly suppressing IL-10 expression level, an immunosuppressive cytokine that inhibits leishmanicidal immune function and encourages disease progression. In conclusion, tuzin immunizations substantially increase the protective immune response in L. donovani-challenged mice groups compared with control.

Impact of Foliar Application of ZnO and Fe3O4 Nanoparticles on Seed Yield and Physio-Biochemical Parameters of Cucumber (Cucumis sativus L.) Seed under Open Field and Protected Environment vis a vis during Seed Germination.

Nutritionally rich cucumber seeds remain in demand in the agricultural, health and cosmetic sectors as they are essential for a successful crop stand establishment and seed-based products. However, the production of cucumber seeds is impeded by source limitation and nutrient deficiency. The foliar application of micronutrients can supplement this deficiency and overcome the physiological setback. An experiment was undertaken to compare the impacts of the foliar application of Fe and Zn, as nanoparticles and fertilizers, on the yield and seed quality of cucumber under open and protected environments. A foliar spray of nano-ZnO (ZnNPs) and nano-Fe3O4 (FeNPs) at 100, 200 and 300 mg L-1, as well as ZnSO4 and FeSO4 as fertilizer (0.5%), was conducted at the vegetative stage and pre- and post-flowering stages. The NPs had a greater efficacy in an open field than in the protected (naturally ventilated poly house) environment. The application of both NPs increased seed yield (51.7-52.2%), total chlorophyll content (15.9-17.3%) and concentration of Zn and Fe in the fruit and the seed, by 2.0-58.5% and 5.0-30.5%, respectively. A significant increase in starch, soluble proteins, soluble sugars and oil content was observed in the seeds from the NP treated plants. NP treatment also enhanced the germination-related parameters, such as percent germination (16.8-17.0%), rate of germination (18.0-22.2%) and seedling vigor (59.8-72.6%). The biochemical characterization showed a significant improvement in the seed water uptake and the activity of hydrolytic enzymes (amylase and protease) in the germinating seed. The involvement of reactive oxygen species (superoxide anion and hydrogen peroxide) and antioxidant enzymes (Superoxide dismutase, Catalase and Peroxidase) in the germination process was indicated by an increase in their activities in the seeds from NP treated plants. Hence, the study proposes the potential benefit of the foliar application of 300 mg L-1 ZnNPs and 200 mg L-1 FeNPs at crucial stages of plant growth to improve the yield and seed quality in cucumbers.

Impact of High Night Temperature on Yield and Pasting Properties of Flour in Early and Late-Maturing Wheat Genotypes.

The inexorable process of climate change in terms of the rise in minimum (nighttime) temperature delineates its huge impact on crop plants. It can affect the yield and quality of various crops. We investigated the effect of high night temperature (HNT) (+2.3 °C over ambient) from booting to physiological maturity on the yield parameters, grain growth rate (GGR), starch content, composition, and flour rheological properties in early (HI 1544, HI 1563) and late-maturing (HD 2932) wheat genotypes. The change in yield under HNT was highly correlated with grain number per plant (r = 0.740 ***) and hundred-grain weight (r = 0.628 **), although the reduction in grain weight was not significantly different. This was also reflected as an insignificant change in starch content (except in HI 1544). Under HNT, late-sown genotypes (HI 1563 and HD 2932) maintained high GGR compared to the timely sown (HI 1544) genotype during the early period of grain growth (5 to 10 days after anthesis), which declined during the later phase of grain development. The increased rheological properties under HNT can be attributed to a significant reduction in the amylose to amylopectin (AMY/AMP) ratio in early-maturity genotypes (HI 1544 and HI 1563). The AMY/AMP ratio was positively correlated to flour rheological parameters (except setback from peak) under HNT. Our study reports the HNT-induced change in the amylose/amylopectin ratio in early maturing wheat genotypes, which determines the stability of flour starches for specific end-use products.

Palladium encapsulated nanofibres for scavenging ethylene from sapota fruits.

Scavenging ethylene is a useful intervention during the transportation and storage of tropical climacteric fruits like sapota. Sapota (Manilkara achras Mill.) is a delicious tropical fruit with a very high respiration rate and poor shelf life. To prolong its post-harvest shelf life, the use of palladium chloride in electrospun nanomats was evaluated at a concentration varying from 1 to 4% levels. Encapsulation of 1-2% PdCl2 in nanomats increased the ethylene scavenging capacity (ESC) by 47-68%. Although, upon encapsulation, both PdCl2 and potassium permanganate showed significantly the same ethylene scavenging activity, the efficacy of PdCl2 was found better in presence of sapota fruits. The PdCl2 nanomats were brighter (L* > 73) in colour compared to the potassium permanganate mat. The placement of nanomats (2 cm2 × 9 cm2) in corrugated fibre board boxes in which the sapota was packed showed higher quality indices (firmness, TSS, ascorbic acid, and phenolics) along with lower PLW and respiration rate during the 8 days of storage period. Compared to control (8.35%), physiological loss in weight of 4.47% was recorded in fruits stored with ethylene scavenging nanomats. PdCl2 encapsulated PVA nanomats can emerge as a promising option for the retention of quality in fruits during storage and transit.

Characterization of crtRB1- and vte4-based biofortified sweet corn inbreds for seed vigour and physico-biochemical traits.

Sweet corn possessing recessive shrunken2 (sh2) gene is popular worldwide. Traditional sweet corn is poor in vitamin A and vitamin E. Plant breeders during the selection of sweet corn genotypes mainly emphasize on plant architecture and yield. Seed germination and seedling vigour play important role for early establishment in field, thereby increasing yield and income. Here, we analysed a set of 15 sh2-based biofortified sweet corn inbreds with crtRB1 (ß-carotene hydroxylase1) and vte4 (γ-tocopherol methyltransferase) genes and three traditional sh2-based sweet corn inbreds for nutritional quality, seed vigour and various physico-biochemical traits. The newly developed inbreds possessed significantly higher provitamin A (proA: 15.60 µg/g) and vitamin E [α-tocopherol (α-T): 20.42 µg/g] than the traditional sweet corn inbreds (proA: 2.51 µg/g, α-T: 11.16 µg/g). The biofortified sweet corn inbreds showed wide variation for germination (80.67-87.33%), vigour index-I (2097.17-2925.28 cm), vigour index-II (134.27-216.19 mg) and electrical conductivity (10.19-13.21 µS cm-1 g-1). Wide variation was also observed for dehydrogenase (1.29-1.59 OD g-1 ml-1), super oxide dismutase (4.01-9.82 g-1), peroxidase (11.66-16.47 µM min-1 g-1), esterase (22.98-34.76 nM min-1 g-1) and α-amylase (5.91-8.15 OD g-1 ml-1). Enrichment of proA and vitamin E in sweet corn did not affect seed vigour and physico-biochemical traits. Correlation analysis revealed that electrical conductivity and α-amylase activity was the reliable indicator for assessing seed germination and vigour. The study identified superior biofortified sweet corn genotypes that would contribute to better vigour and establishment in field. This is the first report of analysis of biofortified sweet corn genotypes for seed vigour and physico-biochemical traits.

Magnetopriming Actuates Nitric Oxide Synthesis to Regulate Phytohormones for Improving Germination of Soybean Seeds under Salt Stress.

In this study, the role of the signalling molecule nitric oxide (NO) in magnetopriming-mediated induction of salinity tolerance in soybean seeds is established. The cross-talk of NO with germination-related hormones gibberellic acid (GA), abscisic acid (ABA) and auxin (IAA) for their ability to reduce the Na+/K+ ratio in the seeds germinating under salinity is highlighted. Salt tolerance index was significantly high for seedlings emerging from magnetoprimed seeds and sodium nitroprusside (SNP, NO-donor) treatment. The NO and superoxide (O2•-) levels were also increased in both of these treatments under non-saline and saline conditions. NO generation through nitrate reductase (NR) and nitric oxide synthase-like (NOS-like) pathways indicated the major contribution of NO from the NR-catalysed reaction. The relative expression of genes involved in the NO biosynthetic pathways reiterated the indulgence of NR in NO in magnetoprimed seeds, as a 3.86-fold increase in expression was observed over unprimed seeds under salinity. A 23.26-fold increase in relative expression of NR genes by the NO donor (SNP) was observed under salinity, while the NR inhibitor (sodium tungstate, ST) caused maximum reduction in expression of NR genes as compared to other inhibitors [L-NAME (N(G)-nitro-L-arginine methyl ester; inhibitor of nitric oxide synthase-like enzyme) and DPI (diphenylene iodonium; NADPH oxidase inhibitor)]. The ratio of ABA/GA and IAA/GA decreased in magnetoprimed and NO donor-treated seeds, suggesting homeostasis amongst hormones during germination under salinity. The magnetoprimed seeds showed low Na+/K+ ratio in all treatments irrespective of NO inhibitors. Altogether, our results indicate that a balance of ABA, GA and IAA is maintained by the signalling molecule NO in magnetoprimed seeds which lowers the Na+/K+ ratio to offset the adverse effects of salinity in soybean seeds.

Sugar metabolism during pre- and post-fertilization events in plants under high temperature stress.

High temperature challenges global crop production by limiting the growth and development of the reproductive structures and seed. It impairs the developmental stages of male and female gametogenesis, pollination, fertilization, endosperm formation and embryo development. Among these, the male reproductive processes are highly prone to abnormalities under high temperature at various stages of development. The disruption of source-sink balance is the main constraint for satisfactory growth of the reproductive structures which is disturbed at the level of sucrose import and utilization within the tissue. Seed development after fertilization is affected by modulation in the activity of enzymes involved in starch metabolism. In addition, the alteration in the seed-filling rate and its duration affects the seed weight and quality. The present review critically discusses the role of sugar metabolism in influencing the various stages of gamete and seed development under high temperature stress. It also highlights the interaction of the sugars with hormones that mediate the transport of sugars to sink tissues. The role of transcription factors for the regulation of sugar availability under high temperature has also been discussed. Further, the omics-based systematic investigation has been suggested to understand the synergistic or antagonistic interactions between sugars, hormones and reactive oxygen species at various points of sucrose flow from source to sink under high temperature stress.

Metal tolerance in plants: Molecular and physicochemical interface determines the "not so heavy effect" of heavy metals.

An increase in technological interventions and ruthless urbanization in the name of development has deteriorated our environment over time and caused the buildup of heavy metals (HMs) in the soil and water resources. These heavy metals are gaining increased access into our food chain through the plant and/or animal-based products, to adversely impact human health. The issue of how to restrict the entry of HMs or modulate their response in event of their ingress into the plant system is worrisome. The current knowledge on the interactive-regulatory role and contribution of different physical, biophysical, biochemical, physiological, and molecular factors that determine the heavy metal availability-uptake-partitioning dynamics in the soil-plant-environment needs to be updated. The present review critically analyses the interactive overlaps between different adaptation and tolerance strategies that may be causally related to their cellular localization, conjugation and homeostasis, a relative affinity for the transporters, rhizosphere modifications, activation of efflux pumps and vacuolar sequestration that singly or collectively determine a plant's response to HM stress. Recently postulated role of gaseous pollutants such as SO2 and other secondary metabolites in heavy metal tolerance, which may be regulated at the whole plant and/or tissue/cell is discussed to delineate and work towards a "not so heavy" response of plants to heavy metals present in the contaminated soils.

Complex target SELEX-based identification of DNA aptamers against Bungarus caeruleus venom for the detection of envenomation using a paper-based device.

Complex target SELEX always have been an intriguing approach to the scientific community, as it offers the potential discovery of novel biomarkers. We herein successfully performed SELEX on Bungarus caeruleus venom to develop a panel of highly affine aptamers that specifically recognizes the B. caeruleus (common krait) venom and was able to discriminate the B. caeruleus venom from Cobra, Russell's, and Saw-scaled viper's venom. The aptamers generated against the crude venom also lead to the identification of the specific component of the venom, which is ß-Bungarotoxin, a toxin uniquely present in the B. caeruleus venom. The best performing aptamer candidates were used as a molecular recognition element in a paper-based device and were able to detect as low as 2 ng krait venom in human serum background. The developed aptamer-based paper device can be used for potential point-of-care venom detection applications due to its simplicity and affordability.

A novel G-quadruplex aptamer-based spike trimeric antigen test for the detection of SARS-CoV-2.

The recent SARS-CoV-2 outbreak has been declared a global health emergency. It will take years to vaccinate the whole population to protect them from this deadly virus, hence the management of SARS-CoV-2 largely depends on the widespread availability of an accurate diagnostic test. Toward addressing the unmet need of a reliable diagnostic test in the current work by utilizing the power of Systematic Evolution of Ligands by EXponential enrichment, a 44-mer G-quadruplex-forming DNA aptamer against spike trimer antigen of SARS-CoV-2 was identified. The lead aptamer candidate (S14) was characterized thoroughly for its binding, selectivity, affinity, structure, and batch-to-batch variability by utilizing various biochemical, biophysical, and in silico techniques. S14 has demonstrated a low nanomolar KD, confirming its tight binding to a spike antigen of SARS-CoV-2. S14 can detect as low as 2 nM of antigen. The clinical evaluation of S14 aptamer on nasopharyngeal swab specimens (n = 232) has displayed a highly discriminatory response between SARS-CoV-2 infected individuals from the non-infected one with a sensitivity and specificity of ∼91% and 98%, respectively. Importantly, S14 aptamer-based test has evinced a comparable performance with that of RT-PCR-based assay. Altogether, this study established the utility of aptamer technology for the detection of SARS-CoV-2.

Hydrogen sulfide: An emerging signaling molecule regulating drought stress response in plants.

Hydrogen sulfide (H2 S) is a small, reactive signaling molecule that is produced within chloroplasts of plant cells as an intermediate in the assimilatory sulfate reduction pathway by the enzyme sulfite reductase. In addition, H2 S is also produced in cytosol and mitochondria by desulfhydration of l-cysteine catalyzed by l-cysteine desulfhydrase (DES1) in the cytosol and from ß-cyanoalanine in mitochondria, in a reaction catalyzed by ß-cyano-Ala synthase C1 (CAS-C1). H2 S exerts its numerous biological functions by post-translational modification involving oxidation of cysteine residues (RSH) to persulfides (RSSH). At lower concentrations (10-1000 µmol L-1 ), H2 S shows huge agricultural potential as it increases the germination rate, the size, fresh weight, and ultimately the crop yield. It is also involved in abiotic stress response against drought, salinity, high temperature, and heavy metals. H2 S donor, for example, sodium hydrosulfide (NaHS), has been exogenously applied on plants by various researchers to provide drought stress tolerance. Exogenous application results in the accumulation of polyamines, sugars, glycine betaine, and enhancement of the antioxidant enzyme activities in response to drought-induced osmotic and oxidative stress, thus, providing stress adaptation to plants. At the biochemical level, administration of H2 S donors reduces malondialdehyde content and lipoxygenase activity to maintain the cell integrity, causes abscisic acid-mediated stomatal closure to prevent water loss through transpiration, and accelerates the photosystem II repair cycle. Here, we review the crosstalk of H2 S with secondary messengers and phytohormones towards the regulation of drought stress response and emphasize various approaches that can be addressed to strengthen research in this area.

Raffinose accumulation and preferential allocation of carbon (14 C) to developing leaves impart salinity tolerance in sugar beet.

Sugar beet is a salt-tolerant crop that can be explored for crop production in degraded saline soils. Seeds of multigerm genotypes LKC-2006 (susceptible) and LKC-HB (tolerant) were grown in 150 mM NaCl, from germination to 60 days after sowing, to decipher the mechanism of salinity tolerance at the vegetative stage. The biomass of the root and leaf were maintained in the tolerant genotype, LKC-HB, under saline conditions. Na+ /K+ ratios were similar in roots and leaves of LKC-HB, with lower values under salinity compared to LKC 2006. Infrared temperatures were 0.96°C lower in LKC-HB than in LKC-2006, which helped regulate the leaf water status under stressed conditions. Pulse-chase experiment showed that 14 C photosynthate was preferentially allocated towards the development of new leaves in the tolerant genotype. The sugar profile of leaves and roots showed accumulation of raffinose in leaves of LKC-HB, indicating a plausible role in imparting salinity tolerance by serving as an osmolyte or scavenger. The molecular analysis of the genes responsible for raffinose synthesis revealed an 18-fold increase in the expression of BvRS2 in the tolerant genotype, suggesting its involvement in raffinose synthesis. Our study accentuated that raffinose accumulation in leaves is vital for inducing salinity tolerance and maintenance of shoot dry weight in sugar beet.

Development of DNA Aptamers to Visualize Release of Mycobacterial Membrane-Derived Extracellular Vesicles in Infected Macrophages.

Extracellular vesicles (EVs) have emerged into a novel vaccine platform, a biomarker and a nano-carrier for approved drugs. Their accurate detection and visualization are central to their utility in varied biomedical fields. Owing to the limitations of fluorescent dyes and antibodies, here, we describe DNA aptamer as a promising tool for visualizing mycobacterial EVs in vitro. Employing SELEX from a large DNA aptamer library, we identified a best-performing aptamer that is highly specific and binds at nanomolar affinity to EVs derived from three diverse mycobacterial strains (pathogenic, attenuated and avirulent). Confocal microscopy revealed that this aptamer was not only bound to in vitro-enriched mycobacterial EVs but also detected EVs that were internalized by THP-1 macrophages and released by infecting mycobacteria. To the best of our knowledge, this is the first study that detects EVs released by mycobacteria during infection in host macrophages. Within 4 h, most released mycobacterial EVs spread to other parts of the host cell. We predict that this tool will soon hold huge potential in not only delineating mycobacterial EVs-driven pathogenic functions but also in harboring immense propensity to act as a non-invasive diagnostic tool against tuberculosis in general, and extra-pulmonary tuberculosis in particular.

GOLD SELEX: a novel SELEX approach for the development of high-affinity aptamers against small molecules without residual activity.

GOLD SELEX, a novel SELEX approach has been developed that obviates the need for target immobilization for aptamer development. The approach purely relies on the affinity of the aptamers towards its target, to get detached from the gold nanoparticle (GNP) surface (weak attraction) after binding with its target. Thus, only the completely detached aptamers are selected for the next round of SELEX. This, in-process, also addresses the issue of residual binding and thus improves the sensitivity of the developed aptamers. As a proof of concept for establishing the utility of the approach for small molecules, we have developed aptamers against dichlorvos (DV), a pesticide in just 8 rounds. Using these aptamer candidates, we have developed an aptamer-NanoZyme (GNP having peroxidase mimic activity) based colorimetric assay. The developed aptamer displayed high affinity (Kd in sub micromolar range) and selectivity for DV. The developed assay could detect as low as 15 µM DV. The best-performing aptamer was also able to work in real samples like river water and commercial apple juice. The GOLD SELEX approach developed in this study, we believe, can act as a template for future SELEX strategy development and can replace the conventional SELEX strategy.

Raffinose and Hexose Sugar Content During Germination Are Related to Infrared Thermal Fingerprints of Primed Onion (Allium cepa L.) Seeds.

Priming is used to increase vigor, germination synchronization, seedling growth, and field establishment by advancing metabolic processes within seeds. Seed respiration is a good indicator of the metabolic processes that lead to transition toward germination. Onion seeds (cv. Pusa Ridhi) subjected to osmopriming (-1.5 MPa PEG6000 for 7 days), magnetopriming (100 mT for 30 min) and halopriming (150 mM KNO3 for 6 days), were evaluated at different times of imbibition to study the emergence index and respiration indices such as infrared thermal fingerprint, CO2 evolution rate, cytochrome c oxidase activity, and soluble sugars profile. Haloprimed seeds exhibited 42.5% higher emergence index as compared to unprimed control. Primed and unprimed seeds showed negative values for relative temperature (ΔT) (difference in temperature of seed and its immediate environment). Haloprimed seeds had the lowest values (-4.1 to -2.3°C) compared to other priming treatments over the germination period. Soluble sugars like raffinose, sucrose, glucose, and fructose contents were monitored and it was observed that en masse raffinose, glucose, and fructose levels were (17.5-59.9%) lower in haloprimed seeds over control. A positive correlation (r 2 = 0.504∗∗) was derived between the amount of these sugars and ΔT. Seed respiration, measured as CO2 evolution rate was more for haloprimed seeds that indicated that these soluble sugars were used as respiratory substrates. Significantly higher cytochrome c oxidase activity (40.7-89.8% and 12.5-66.6%) was observed in all primed seeds at 28 and 36 h, respectively. Among the various seed priming methods, halopriming proved to be the most effective priming treatment in onion seeds as evidenced by the higher respiration indices that resulted in faster metabolic rate and emergence index.