Identification of mungbean yellow mosaic India virus and susceptibility-related metabolites in the apoplast of mung bean leaves.

KEY MESSAGE: The investigation of MYMIV-infected mung bean leaf apoplast revealed viral genome presence, increased EVs secretion, and altered stress-related metabolite composition, providing comprehensive insights into plant-virus interactions. The apoplast, an extracellular space around plant cells, plays a vital role in plant-microbe interactions, influencing signaling, defense, and nutrient transport. While the involvement of apoplast and extracellular vesicles (EVs) in RNA virus infection is documented, the role of the apoplast in plant DNA viruses remains unclear. This study explores the apoplast's role in mungbean yellow mosaic India virus (MYMIV) infection. Our findings demonstrate the presence of MYMIV genomic components in apoplastic fluid, suggesting potential begomovirus cell-to-cell movement via the apoplast. Moreover, MYMIV infection induces increased EVs secretion into the apoplast. NMR-based metabolomics reveals altered metabolic profiles in both apoplast and symplast in response to MYMIV infection, highlighting key metabolites associated with stress and defense mechanisms. The data show an elevation of α- and ß-glucose in both apoplast and symplast, suggesting a shift in glucose utilization. Interestingly, this increase in glucose does not contribute to the synthesis of phenolic compounds, potentially influencing the susceptibility of mung bean to MYMIV. Fructose levels increase in the symplast, while apoplastic sucrose levels rise significantly. Symplastic aspartate levels increase, while proline exhibits elevated concentration in the apoplast and reduced concentration in the cytosol, suggesting a role in triggering a hypersensitive response. These findings underscore the critical role of the apoplast in begomovirus infection, providing insights for targeted viral disease management strategies.

Scirpusin B isolated from Passiflora edulis Var. flavicarpa attenuates carbohydrate digestive enzymes, pathogenic bacteria and oral squamous cell carcinoma.

Passiflora edulis Var. flavicarpa (passion fruit) generates vast waste (60-70%) in the form of peel and seed after the juice extraction. The study aimed to isolate Scirpusin B (SB) from passion fruit (PF) seed waste collected from Northeast India and to analyse its anti-radical, antibacterial, anti-diabetic, and anti-oral cancer activities. Scirpusin B was isolated following hydro-alcoholic extraction, fractionation, and column chromatography. The isolated fraction was further identified through NMR and mass spectroscopy. SB exhibited significant antiradical activity against six standard antioxidant compounds, indicating its commercial application. SB inhibited α-amylase (IC50 Value: 76.38 ± 0.25 µg/mL) and α-glucosidase digestive enzymes (IC50 Value: 2.32 ± 0.04 µg/mL), signifying its antidiabetic properties. In addition, SB showed profound antibacterial activity against eight gram-positive and gram-negative bacteria reported for the first time. Furthermore, SB inhibited SAS and TTN oral cancer cell proliferation up to 95% and 83%, respectively. SB significantly inhibited colonies of SAS and TTn cells in the clonogenic assay, attributing to its anticancer properties. The PI-FACS assay confirmed the ability of SB (75 µM) to kill SAS and TTn cells by 40.26 and 44.3% in 72 h. The mechanism of SB inhibiting oral cancer cell proliferation was understood through western blot analysis, where SB significantly suppressed different cancer hallmark proteins, such as TNF-α, survivin, COX-2, cyclin D1, and VEGF-A. The present study suggests that SB isolated from PF seed can add noteworthy value to the waste biomass for various industrial and medical applications. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03876-6.

UiO-66 octahedrons for adsorptive removal of direct blue-6: process optimization, interaction mechanism, and phytotoxicity assessment.

The materials for water treatment have been evolving in multitude of dimensions, indicating the importance of water reuse and increasing level of water pollution around the globe. Among the various materials that are utilized in wastewater treatment, the material that has attracted the research community for the past decades is the metal organic framework (MOF). In this work one of the water stable and microporous MOF, UiO-66, and its aminated version has been employed to adsorb an anionic azo dye, direct blue-6 (DB-6), from the aqueous matrix. Performance of both the MOFs was compared to know the efficiency under varying solution conditions. The optimized parameters for DB-6 adsorption by UiO-66 was performed using response surface methodology. This numerical optimization was further extended with canonical and ridge analysis. Under optimal conditions, the materials were exhibiting a good adsorption capacity of 754.4 mg/g. The materials were analyzed in terms of morphology, crystallinity, thermal stability, and surface area using instruments like X-ray diffraction, electron microscopy, thermogravimetric analysis, and BET surface area analysis. The mechanism of interaction between UiO-66 and DB-6 molecule was elucidated with the help of XPS analysis which helps to know the main interacting group of UiO-66. This study was concluded with a phytotoxicity analysis of DB-6 and the antioxidant system of Vigna radiata assessed using pre and post adsorbed water.

Acclimation-driven microalgal cultivation improved temperature and light stress tolerance, CO2 sequestration and metabolite regulation for bioenergy production.

This study investigates temperature and light impact on the ability of Micractinium pusillum microalgae to mitigate CO2 and produce bioenergy in semi-continuous mode. Microalgae were exposed to temperatures (15, 25, and 35 °C) and light intensities (50, 350, and 650 µmol m-2 s-1), including two temperature cycles, 25 °C had the maximum growth rate, with no significant difference at 35 °C and light intensities of 350 and 650 µmol m-2 s-1. 15 °C temperature and 50 µmol m-2 s-1 light intensity reduced growth. Increased light intensity accelerated growth, CO2 utilization with carbon and bioenergy accumulation. Microalgae demonstrate rapid primary metabolic adjustment and acclimation reactions in response to changes in light and temperature conditions. Temperature correlated positively with carbon and nitrogen fixation, CO2 fixation, and carbon accumulation in the biomass, whereas there was no correlation found between light. In the temperature regime experiment, higher light intensity boosted nutrient and CO2 utilization, carbon buildup, and biomass bioenergy.

Isolation and Characterization of Stress-Tolerant Priestia Species from Cowpea Rhizosphere Under Drought and Nutrient Deficit Conditions.

This study aimed to isolate stress-tolerant phytobeneficial bacteria as bio-inoculants for cowpea's sustainable growth under drought and nutrient deficiency conditions. However, the application successful of phytobeneficial bacteria is subject to effective in vitro screening under different physiological conditions. We isolated several Priestia species from cowpea rhizosphere that tolerates polyethylene glycol (PEG6000)-induced drought and nutrient deficiency. Of them, C8 (Priestia filamentosa; basonym: Bacillus filamentosus), followed by C29 (Priestia aryabhattai; basonym: Bacillus aryabhattai), tolerated up to 20% PEG in a low-nutrient medium. In the presence of PEG, Priestia filamentosa and Bacillus aryabhattai exhibited optimal growth in different temperatures and pH but failed to survive at extreme temperatures of 45 °C and pH 11. Priestia filamentosa preferred L-proline and L-glutamate, while L-tryptophan and L-tyrosine were the least utilized. Interestingly, Priestia filamentosa and Bacillus aryabhattai used more complex nitrogen sources, peptone, and yeast extract, than inorganic nitrogen for growth. Most importantly, under drought and nutrient deficiency, Priestia filamentosa exhibited multiple plant growth-promoting traits and more amylase and protease production than C29. Our results indicate that Priestia filamentosa is a potential bacterium to enhance the growth of cowpea plants under stressful conditions.

Molecular Epidemiology of Begomoviruses Infecting Mungbean from Yellow Mosaic Disease Hotspot Regions of India.

The major threat to mungbean (Vigna radiata L.) cultivation in the Indian subcontinent is yellow mosaic diseases (YMD), caused by Begomovirus containing bipartite genomes (DNA-A and DNA-B). In the current study, we address the epidemiology of begomoviruses infecting mungbean plants in three YMD hotspot regions of India. Full-length genomic components of the viruses from the symptomatic leaves were cloned by rolling circle amplification (RCA) and sequenced. Mungbean yellow mosaic virus (MYMV) was detected in Bihar and mungbean yellow mosaic India virus (MYMIV) in Assam and Orissa. Furthermore, we studied the population structure and genetic diversity of MYMV and MYMIV isolates of Vigna species reported to date from India. Interestingly, based on phylogenetics, we observed independent evolution of DNA-A and coevolution of DNA-B of MYMV and MYMIV. This finding is supported by the high mutation rate and recombination events in DNA-B, particularly in BV1 and BC1 genes over DNA-A, with high transition/transversion bias (R) for DNA-A over DNA-B. To investigate the effect of Begomovirus infection in plants, we constructed infectious clones (i.e. MYMV and MYMIV) and inoculated them to eight mungbean genotypes, cowpea (Vigna unguiculata L.) and tobacco (Nicotiana benthamiana) through agroinfiltration. The infected plants developed varying degrees of typical YMD symptoms. Based on the disease severity score and viral titre, mungbean genotypes were categorized as highly susceptible to MYMV (ML267) and MYMIV (K851) and immune to MYMV (PDM139, SML668) and MYMIV (Pusa Vishal). Conclusively, our findings may help prevent an epidemic of YMD in Vigna species and develop mungbean genotypes resistant to YMD via breeding programs.

Cowpea NAC1/NAC2 transcription factors improve growth and tolerance to drought and heat in transgenic cowpea through combined activation of photosynthetic and antioxidant mechanisms.

NAC (NAM/ATAF1/2/CUC2) transcription factors are central switches of growth and stress responses in plants. However, unpredictable interspecies conservation of function and regulatory targets makes the well-studied NAC orthologs inapt for pulse engineering. The knowledge of suitable NAC candidates in hardy pulses like cowpea (Vigna unguiculata (L.) Walp.) is still in infancy, hence warrants immediate biotechnological intervention. Here, we showed that overexpression of two native NAC genes (VuNAC1 and VuNAC2) promoted germinative, vegetative, and reproductive growth and conferred multiple abiotic stress tolerance in a commercial cowpea variety. The transgenic lines displayed increased leaf area, thicker stem, nodule-rich denser root system, early flowering, higher pod production (∼3.2-fold and ∼2.1-fold), and greater seed weight (10.3% and 6.0%). In contrast, transient suppression of VuNAC1/2 caused severe growth retardation and flower inhibition. The overexpressor lines showed remarkable tolerance to major yield-declining terminal stresses, such as drought, salinity, heat, and cold, and recovered growth and seed production by boosting photosynthetic activity, water use efficiency, membrane integrity, Na+ /K+ homeostasis, and antioxidant activity. The comparative transcriptome study indicated consolidated activation of genes involved in chloroplast development, photosynthetic complexes, cell division and expansion, cell wall biogenesis, nutrient uptake and metabolism, stress response, abscisic acid, and auxin signaling. Unlike their orthologs, VuNAC1/2 direct synergistic transcriptional tuning of stress and developmental signaling to avoid unwanted trade-offs. Their overexpression governs the favorable interplay of photosynthesis and reactive oxygen species regulation to improve stress recovery, nutritional sufficiency, biomass, and production. This unconventional balance of strong stress tolerance and agronomic quality is useful for translational crop research and molecular breeding of pulses.

Rhizosphere Priestia species altered cowpea root transcriptome and enhanced growth under drought and nutrient deficiency.

MAIN CONCLUSION: Priestia species isolated from the cowpea rhizosphere altered the transcriptome of cowpea roots by colonization and enhanced nutrient uptake, antioxidant mechanisms, and photosynthesis, protecting cowpea from drought and nutrient deficiency. Cowpea is a significant grain legume crop primarily grown in sub-Saharan Africa, Asia, and South America. Drought and nutrient deficiency affect the growth and yield of cowpea. To address this challenge, we studied the phyto-beneficial effects of stress-tolerant rhizobacteria on the biomass yield of cowpea under water- and nutrient-deficit conditions. Among the bacteria isolated, two rhizobacillus genotypes, C8 (Priestia filamentosa; basonym: Bacillus filamentosus) and C29 (Priestia aryabhattai; basonym: Bacillus aryabhattai) were evaluated for the improvement of seed germination and growth of cowpea under stress. Our study revealed that C8 protected cowpea from stress by facilitating phosphorus and potassium uptake, protecting it from oxidative damage, reducing transpiration, and enhancing CO2 assimilation. A 17% increase in root biomass upon C8 inoculation was concomitant with the induction of stress tolerance genes in cowpea roots predominantly involved in growth and metabolic processes, cell wall organization, ion homeostasis, and cellular responses to phosphate starvation. Our results indicate a metabolic alteration in cowpea root triggered by P. filamentosa, leading to efficient nutrient reallocation in the host plant. We propose inoculation with P. filamentosa as an effective strategy for improving the yield of cowpea in low-input agriculture, where chemical fertilization and irrigation are less accessible to resource-poor farmers.

Rapid and precise detection of cryptic tea pathogen Exobasidium vexans: RealAmp validation of LAMP approach.

This work embodies the development of a real time loop mediated isothermal amplification (RealAmp) assay for the rapid detection of the cryptic tea phytopathogen, Exobasidium vexans, the causal organism of blister blight disease. Due to the widespread popularity of tea as a beverage and the associated agro-economy, the rapid detection and management of the fast-spreading blister blight disease have been a longstanding necessity. Loop-mediated isothermal amplification (LAMP) primers were designed targeting the E. vexans ITS rDNA region and the reaction temperature was optimized at 62 °C with a 60 min reaction time. Amplification of the E. vexans isolates in the initial LAMP reactions was confirmed by both agarose gel electrophoresis and SYBR Green I dye based colour change visualization. The specificity of the LAMP primers for E. vexans was validated by negative testing of seven different phytopathogenic test fungi using LAMP and RealAmp assay. The positive findings in RealAmp assay for E. vexans strain were corroborated via detecting fluorescence signals in real-time. Further, the LAMP assays performed with gDNA isolated from infected tea leaves revealed positive amplification for the presence of E. vexans. The results demonstrate that this rapid and precise RealAmp assay has the potential to be applied for field-based detection of E. vexans in real-time.

Optimization of polyphenol extraction from Hippophae salicifolia D. Don leaf using supercritical CO2 by response surface methodology.

In this study, an eco-friendly supercritical carbon dioxide (SC-CO2) extraction of polyphenolic compounds from Hippophae salicifolia leaf was optimized to achieve the highest extraction yield with maximum total phenolic content (TPC) and minimum IC50. The central composite design was used to establish an experimental design for RSM. The effect of the pressure, temperature, carbon dioxide flow rate, and co-solvent amount was scrutinized using variance analysis (ANOVA). Under optimized condition (25.13 MPa, 47.53 °C, 14.47 g/min, and 2.43%), the experimental data (yield of extraction: 4.38%, TPC: 84.31 mg GAE/g, and IC50: 41.94 µg/mL) showed good agreement with the predicted values (yield of extraction: 4.53%, TPC: 83.37 mg GAE/g, and IC50: 40.2 µg/mL). Nine polyphenolic compounds: gallic acid, caffeic acid, ferulic acid, vanillic acid, p-coumaric acid, quercetin, myricetin, kaempferol, and rutin were analyzed in SC-CO2 extract using HPLC. SC-CO2 extraction was more selective for ferulic acid, myricetin, and quercetin extraction. The study results revealed that SC-CO2 extract had significant antibacterial activity against eight bacterial strains. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03358-1.

Enhanced osmotic adjustment, antioxidant defense, and photosynthesis efficiency under drought and heat stress of transgenic cowpea overexpressing an engineered DREB transcription factor.

Cowpea is sensitive to drought and heat stress, particularly at the reproductive stages of development. Both stresses limit growth and yield, and their effect is more devastating when occurring concurrently. Dehydration-responsive element-binding protein 2A (DREB2A) is an important signaling hub integrating information about two different abiotic stresses, drought and heat. We identified VuDREB2A as a canonical DREB ortholog in cowpea, activating downstream stress-responsive genes by binding to DREs in their promoter. Post-translational modification of a negative regulatory domain (NRD) within the VuDREB2A protein prevents its degradation. Targeted deletion of the NRD produces a stable and constitutively active form VuDREB2A-CA. However, there is very little evidence of its practical utility under field conditions. This study overexpressed the VuDREB2A-CA in a popular cowpea variety and conducted drought- and heat-tolerance experiments across various stress regimes. Transgenic cowpea exhibited significant tolerance with consistently higher yield when exposed to over 30-d drought stress and 3-d exposure to high temperature (28 °C-52 °C) without any pleiotropic alterations. The transgenic lines showed higher photosynthetic efficiency, osmotic adjustment, antioxidant defense, thermotolerance, and significantly higher survival and increased biomass than the wild type. Late embryogenesis abundant 5, heat shock protein 70, dehydrin, mitogen-activated protein kinase 2/4, isoflavonoid reductase, and myoinositol phosphate synthase were upregulated in transgenic lines under drought and heat stress. Through transcriptome analysis of the transgenic lines, we found significant up-regulation of various stress-responsive cowpea genes, having DRE in their promoter. Our results suggest that overexpression of VuDREB2A could improve cowpea production under drought and high temperatures.

NMR-Based Metabolomic Profiling of Mungbean Infected with Mungbean Yellow Mosaic India Virus.

Mungbean is an important legume mainly cultivated in Southeast Asia known for cheap source of food protein. Yellow mosaic disease (YMD) of mungbean is one of the most damaging diseases caused by mungbean yellow mosaic virus (MYMV) and mungbean yellow mosaic India virus (MYMIV) in India. The genetic basis of YMD resistance of mungbean is not well studied yet. Our present studies aimed to explore the genetic basis of YMD resistance through molecular, biochemical and metabolomics approach. Molecular analysis of YMV-infected mungbean plant materials revealed the presence of MYMIV. Chlorophyll contents were estimated as mosaic symptoms that cause chlorosis and necrosis in infected leaves. Chlorophyll a, b and total chlorophyll content were significantly reduced by 27-55% in infected samples compared non-infected control samples. 1H NMR-based metabolomic profiling of virus-infected mungbean were carried out, and we found that vital changes occurred during the development of MYMIV infection in mungbean. A total of fifty metabolites were identified in mungbean leaf samples. Principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA) separated the severely infected sample from the non-infected samples. Orthogonal partial least discrimination analysis (OPLS-DA) revealed significant differences in MYMIV-infected and non-infected control samples. The featured metabolites in MYMIV infected and control samples were amino acids, carbohydrates, and organic acids. Relative abundance of sucrose, γ-amino butyric acid (GABA), proline, alanine, phenylalanine, tryptophan, pyruvate, ascorbate, and citrates were found as differential metabolites. Our results suggest that metabolic changes in infected mungbean samples is related to the viral acquisition. The present study may help in better understanding the metabolic alterations during biotic stress in mungbean.

Bacillus aryabhattai enhanced proline content, stabilized membrane and improved growth of cowpea under NaCl-induced salinity stress.

AIMS: Salinity stress affects the growth of cowpea particularly at the stages of seed germination and early vegetative growth. This study examined the potential of particular stress-tolerant rhizospheric bacteria to improve the growth of cowpea under conditions of salinity stress. METHODS AND RESULTS: Two rhizobacillus genotypes, Bacillus filamentosus-C8 and Bacillus aryabhattai-C29 were evaluated for their potentials to protect cowpea under NaCl-induced salinity stress. At 200 mM of NaCl concentration, control (non-inoculated) cowpea was affected, C8 was not able to significantly (p ≤ 0.05) alleviate the effects of salinity stress on cowpea growth while C29 significantly (p ≤ 0.05) reduced leaf wilting, increased chlorophyll content and improved the growth of cowpea plant under stressed condition. Interestingly, C29 significantly (p ≤ 0.05) induced high proline content and stabilized membrane by loss of electrolytes. CONCLUSION: Our results indicate that stabilized membrane and enhanced proline content by Bacillus aryabhattai-C29 supported the growth of cowpea under salinity stress condition. SIGNIFICANCE AND IMPACT OF THE STUDY: This study revealed that rhizospheric bacteria screened for salinity stress tolerant have potential to be used as an effective bioprotectant for sustainable growth of cowpea under salinity stress condition.

How do plants remember drought?

MAIN CONCLUSION: Plants develop both short-term and transgenerational memory of drought stress through epigenetic regulation of transcription for a better response to subsequent exposure. Recurrent spells of droughts are more common than a single drought, with intermittent moist recovery intervals. While the detrimental effects of the first drought on plant structure and physiology are unavoidable, if survived, plants can memorize the first drought to present a more robust response to the following droughts. This includes a partial stomatal opening in the watered recovery interval, higher levels of osmoprotectants and ABA, and attenuation of photosynthesis in the subsequent exposure. Short-term drought memory is regulated by ABA and other phytohormone signaling with transcriptional memory behavior in various genes. High levels of methylated histones are deposited at the drought-tolerance genes. During the recovery interval, the RNA polymerase is stalled to be activated by a pause-breaking factor in the subsequent drought. Drought leads to DNA demethylation near drought-response genes, with genetic control of the process. Progenies of the drought-exposed plants can better adapt to drought owing to the inheritance of particular methylation patterns. However, a prolonged watered recovery interval leads to loss of drought memory, mediated by certain demethylases and chromatin accessibility factors. Small RNAs act as critical regulators of drought memory by altering transcript levels of drought-responsive target genes. Further studies in the future will throw more light on the genetic control of drought memory and the interplay of genetic and epigenetic factors in its inheritance. Plants from extreme environments can give queues to understanding robust memory responses at the ecosystem level.

Overexpression of cowpea NAC transcription factors promoted growth and stress tolerance by boosting photosynthetic activity in Arabidopsis.

ATAF-like NAC transcription factors are bonafide regulators of stress-signaling. However, their overexpression often exerts growth-retardation by activating ABA-hypersensitivity, chloroplast-degradation, or carbon-starvation. To improve tolerance to multiple stress complying with growth sustainability, we examined two ATAF orthologs, VuNAC1 and VuNAC2, isolated from a drought-hardy cowpea genotype, for a harmonized regulation of stress and growth signaling. The genes were induced by dehydration, NaCl, polyethylene glycol, heat, cold, ABA, and light. Analysis of the promoter-elements and regulatory network corroborated the integration of circadian, hormonal, stress, developmental, and nutrition signals, being VuNAC1/2 the central transcriptional-switch interfacing growth and stress responses. The constitutive gene overexpression in Arabidopsis resulted in an improved embryonic, rosette, and inflorescence growth, under optimum as well as limiting nutrition, in association with increased photosynthetic activity and stomatal-density. The transgenic seedlings manifested tolerance to dehydration, salinity, aluminum, cadmium, and H2O2 toxicity, in addition to ABA-mediated seed dormancy and hypersensitivity. The soil-grown plants survived severe drought and hypersalinity by maintaining the water-status and membrane integrity through the accumulation of stress protectants, such as proline, glutathione, and ascorbate. Unlike their orthologs from other species, VuNAC1/2 conferred tolerance to multiple abiotic stresses in line with improved growth attributes via regulation of photosynthetic controls and nutritional balance, suggesting growth being a crucial component of stress-tolerance and recovery. Such unique stress-responsive transcription factors, which also confer photosynthetic gain, could be sustainable biotechnological tools for developing stress-tolerant crops and translating the improved growth into yield without unintended trade-offs.

A Method for Developing RNAi-Derived Resistance in Cowpea Against Geminiviruses.

In plants, RNA interference (RNAi) is triggered by double-stranded RNA (dsRNA). Accordingly, various RNA silencing technologies involving hpRNA, artificial microRNA (miRNA), and virus-induced gene silencing (VIGS) are used for controlling the expression of genes. Such manipulations help understanding gene functions and crop improvement biotechnology. A typical hpRNA construct is comprised of an intron splicable perfect inverted repeat of the target gene sequences under the control of a strong promoter. Geminiviruses, especially Mungbean Yellow Mosaic India Virus (MYMIV) cause devastating diseases in legume plants including cowpea, incurring severe crop loss. RNAi, involving hpRNA construct as transgene, is used to control these diseases at the early stages of geminivirus infection in the host, preventing symptom development and viral DNA accumulation. In this chapter, we describe a detailed protocol for the identification of geminivirus isolates from the filed grown cowpea plants, characterization of virus isolates under the laboratory conditions, design and construct RNAi vectors for effective suppression of viral target genes, and consequent development of transgenic cowpea using Agrobacterium-mediated transformation protocol. These transgenics are subsequently evaluated for resistance to MYMIV.

Maximize microalgal carbon dioxide utilization and lipid productivity by using toxic flue gas compounds as nutrient source.

NOx and SOx present in flue gas inhibit microalgal based CO2 mitigation process. In this work, 13 microalgal strains were screened to evaluate their gradual acclimation capacity to toxic flue gas compounds, by testing their growth capability and photosynthetic ability in dissolved flue gas compounds. Six strains out of them were evaluated for their acclimation to bicarbonate and 15% CO2 as sole carbon sources. Two strains, Micractinium pusillum KMC8 and Scenedesmus acutus NCIM5584 were found to accumulate nitrite as fixed nitrogen and showed improved growth performance in photobioreactor upon stepwise acclimation to bisulphite/sulphite. Notably, the strain KMC8 showed a high tolerance and rapidly acclimated dissolved flue gas compounds with higher biomass yield (1.32 g L-1) and neutral lipid accumulation (32%), enhanced CO2 utilization efficiency (3.07%) and CO2 fixation rate (136.79 mg L-1 d-1) post acclimation. KMC8 sustained its stability in biomass and lipid productivity while simultaneously bio-mitigated CO2 under semi-continuous mode.

Exploring relations between plant photochemical quantum parameters and unsaturated soil water retention for biochars and pith amended soils.

Sustainable biomaterials such as natural fibers and biochars have been increasingly used in green infrastructures such as landfill covers for its dual-advantages of climate change mitigation and waste management. The existing studies did not systematically discuss the comparison on how biochar (stable carbon) and fiber (likely degradable), influence plant growth and water retention abilities in unsaturated soils. Also, the effect of photochemistry in the amended soils has rarely been investigated. This study addresses the limitations of previous investigations by exploring plant parameters such as photochemical yield, stomatal conductance, root area index, and unsaturated soil hydraulic parameters, including soil water retention curves (SWRC) of amended soils. Pot experiments were conducted in an environmentally controlled greenhouse. Two biochars from different plant-based feedstocks (Eichhornia crassipes, Prosopis juliflora) and one natural fiber (coir pith fiber) were mixed with soil at 5% and 10% application rate (by weight). Grass species of Axonopus compressus was planted to study the effects of different amendment materials and its corresponding plant responses during an applied drought period. The test results show that biochar amended soils increased the shoot growth by up to 100-200%. The stomatal conductance of the grass leaves increased by 54%-101% during the drought period for both biochars and coir amended soil. Furthermore, at low suction, the coir had a high water retention capacity than the biochars, explaining the observed higher stomatal conductance values. Importantly, it was discovered that the plant photochemical quantum yield responses associated with plant wilting was found to vary between 1500 and 1800 kPa for all the soil treatments. The study concludes with a newly developed mathematical expression based on the measurements of plant parameters and soil suction. The new equation could be used to optimize the irrigation frequency in order to apply any informed measures to maintain green infrastructures.

Cowpea NAC Transcription Factors Positively Regulate Cellular Stress Response and Balance Energy Metabolism in Yeast via Reprogramming of Biosynthetic Pathways.

Yeast is a dominant host for recombinant production of heterologous proteins, high-value biochemical compounds, and microbial fermentation. During bioprocess operations, pH fluctuations, organic solvents, drying, starvation, osmotic pressure, and often a combination of these stresses cause growth inhibition or death, markedly limiting its industrial use. Thus, stress-tolerant yeast strains with balanced energy-bioenergetics are highly desirous for sustainable improvement of quality biotechnological production. We isolated two NAC transcription factors (TFs), VuNAC1 and VuNAC2, from a wild cowpea genotype, improving both stress tolerance and growth when expressed in yeast. The GFP-fused proteins were localized to the nucleus. Y2H and reporter assay demonstrated the dimerization and transactivation abilities of the VuNAC proteins having structural folds similar to rice SNAC1. The gel-shift assay indicated that the TFs recognize an "ATGCGTG" motif for DNA-binding shared by several native TFs in yeast. The heterologous expression of VuNAC1/2 in yeast improved growth, biomass, lifespan, fermentation efficiency, and altered cellular composition of biomolecules. The transgenic strains conferred tolerance to multiple stresses such as high salinity, osmotic stress, freezing, and aluminum toxicity. Analysis of the metabolome revealed reprogramming of major pathways synthesizing nucleotides, vitamin B complex, amino acids, antioxidants, flavonoids, and other energy currencies and cofactors. Consequently, the transcriptional tuning of stress signaling and biomolecule metabolism improved the survival of the transgenic strains during starvation and stress recovery. VuNAC1/2-based synthetic gene expression control may contribute to designing robust industrial yeast strains with value-added productivity.