CcNFYB3-CcMATE35 and LncRNA CcLTCS-CcCS modules jointly regulate the efflux and synthesis of citrate to enhance aluminium tolerance in pigeon pea.

Aluminium (Al) toxicity decreases crop production in acid soils in general, but many crops have evolved complex mechanisms to resist it. However, our current understanding of how plants cope with Al stress and perform Al resistance is still at the initial stage. In this study, the citrate transporter CcMATE35 was identified to be involved in Al stress response. The release of citrate was increased substantially in CcMATE35 over-expression (OE) lines under Al stress, indicating enhanced Al resistance. It was demonstrated that transcription factor CcNFYB3 regulated the expression of CcMATE35, promoting the release of citrate from roots to increase Al resistance in pigeon pea. We also found that a Long noncoding RNA Targeting Citrate Synthase (CcLTCS) is involved in Al resistance in pigeon pea. Compared with controls, overexpression of CcLTCS elevated the expression level of the Citrate Synthase gene (CcCS), leading to increases in root citrate level and citrate release, which forms another module to regulate Al resistance in pigeon pea. Simultaneous overexpression of CcNFYB3 and CcLTCS further increased Al resistance. Taken together, these findings suggest that the two modules, CcNFYB3-CcMATE35 and CcLTCS-CcCS, jointly regulate the efflux and synthesis of citrate and may play an important role in enhancing the resistance of pigeon pea under Al stress.

Nano zinc oxide mediated resuscitation of aged Cajanus cajan via modulating aquaporin, cell cycle regulatory genes and hormonal responses.

KEY MESSAGE: Nanoparticle pretreatment improved the health of aged Cajanus cajan seeds viz., regulation of redox status, gene expression, and restoration of hormonal homeostasis. Ageing deteriorates the quality of seeds by lowering their vigor and viability, and terminating with loss of germination. These days, nanotechnology has been seen to revolutionize the agricultural sectors, and particularly nano zinc oxide (nZnO) has gained considerable interests due to its distinctive properties. The aim of the present work was to decipher the possibilities of using nZnO to rejuvenate accelerated aged (AA) seeds of Cajanus cajan. Both chemically (CnZnO) and green (GnZnO; synthesized using Moringa oleifera) fabricated nZnOs were characterized via standard techniques to interpret their purity, size, and shape. Experimental results revealed erratic germination with a decline in viability and membrane stability as outcomes of reactive oxygen intermediate (ROI) buildup in AA seeds. Application of nZnO substantially rebated the accrual of ROI, along with enhanced production of antioxidants, α-amylase activity, total sugar, protein and DNA content. Higher level of zinc was assessed qualitatively/ histologically and quantitatively in nZnO pulsed AA seeds, supporting germination without inducing toxicity. Meantime, augmentation in the gibberellic acid with a simultaneous reduction in the abscisic acid level were noted in nZnO invigorated seeds than that determined in the AA seeds, suggesting possible involvement of ROI in hormonal signalling. Furthermore, nZnO-subjected AA seeds unveiled differential expression of aquaporins and cell cycle regulatory genes. Summarizing, among CnZnO and GnZnO, later one holds better potential for a revival of AA seeds of Cajanus cajan by providing considerable tolerance against ageing-associated deterioration via recouping the cellular redox homeostasis, hormonal signaling, and alteration in expression patterns of aquaporin and cell cycle regulatory genes.

Mitigation of heavy metal toxicity in pigeon pea by plant growth promoting Pseudomonas alcaliphila strain PAS1 isolated from contaminated environment.

The risk of arsenic contamination is rising globally, and it has negative impacts on the physiological processes and growth of plants. Metal removal from contaminated soils can be accomplished affordably and effectively with plant growth promoting rhizobacteria (PGPR)-based microbial management. From this angle, this research evaluated the mitigation of arsenic toxicity using the bacteria isolated from contaminated site, Mettur, Salem district, South India. The newly isolated bacterial strain was screened for plant growth promotion potential and arsenic tolerance such as (100 ppm, 250 ppm, 500 ppm, 800 ppm and 1200 ppm). The metal tolerant rhizobacteria was identified using 16S rRNA gene sequence analysis as Pseudomonas alcaliphila strain PAS1 (GenBank accession number: OQ804624). Pigeon pea (Cajanus cajan) plants were used in pot culture experiments with varying concentrations of arsenic, (5 ppm, 10 ppm and 25 ppm) both with and without bacterial culture, for a period of 45 days. At the concentration of 25 ppm after the application of PAS1 enhanced the plant growth, protein and carbohydrate by 35.69%, 18.31% respectively. Interestingly, P. alcaliphila strain PAS1 significantly reduced the stress-induced elevated levels of proline, flavonoid, phenol and antioxidant enzyme in pigeon pea plants was 40%, 31.11%, 27.80% and 20.12%, respectively. Consequently, PAS1 may significantly reduce the adverse effects that arsenic causes to plant development in acidic soils, improve plant uptake of nutrients, and increase plant production. The findings of this study reveal that P. alcaliphila PAS1 is intrinsic for phytoremediation by reducing arsenic accumulation in the root and shoot.

Stilbenoids and Flavonoids from Cajanus cajan (L.) Millsp. and Their α-Glucosidase Inhibitory Activities.

Two new stilbenoids, cajanstilbenoid C (1) and cajanstilbenoid D (2), together with eight other known stilbenoids (3-10) and seventeen known flavonoids (11-27), were isolated from the petroleum ether and ethyl acetate portions of the 95% ethanol extract of leaves of Cajanus cajan (L.) Millsp. The planar structures of the new compounds were elucidated by NMR and high-resolution mass spectrometry, and their absolute configurations were determined by comparison of their experimental and calculated electronic circular dichroism (ECD) values. All the compounds were assayed for their inhibitory activities against yeast α-glucosidase. The results demonstrated that compounds 3, 8-9, 11, 13, 19-21, and 24-26 had strong inhibitory activities against α-glucosidase, with compound 11 (IC50 = 0.87 ± 0.05 µM) exhibiting the strongest activity. The structure-activity relationships were preliminarily summarized. Moreover, enzyme kinetics showed that compound 8 was a noncompetitive inhibitor, compounds 11, 24-26 were anticompetitive, and compounds 9 and 13 were mixed-competitive.

Decomposition and nutrient release of green manure biomass in a passion fruit orchard in the brazilian semiarid region.

Green manure decomposition and nutrient recycling improve soil quality and productivity of different crops, but information on irrigated fruit orchards in the Brazilian semi-arid region is still scarce. Decomposition and nitrogen, phosphate, and potassium release from the cut biomass of three green manure legumes (sunn hemp, pigeon pea and jack bean) placed in litterbags, and spontaneous vegetation grown for 90 days in the rows of a passion fruit orchard were followed for 150 days. Biomasses decreased exponentially, reaching 12 (sunn hemp) to 25% (jack beans and spontaneous vegetation) after 150 days. K was rapidly released (< 21 and 4% of the original content remaining after 7 and 150 days, respectively), contrasting with more than half of the P and one third of the N remaining after 150 days. The amounts released were more influenced by the amounts of biomass produced (sunn hemp, 1583); (Jack bean 5152 kg ha-1); (Pigeon pea 822 kg ha-1); (Spontaneous plants 3175 kg ha-1); (spontaneous legumes 744 kg ha-1) than by variation in decomposition proportions among species. N release represented a liquid input to the soil, since more than 80% of the green manure and spontaneous vegetation contents came from N2-symbiotic fixation. Therefore, green manure is an effective technique to incorporate N and recycle K and P in irrigated orchards in the Brazilian semi-arid region.

Distribution and pathogenic diversity in Fusarium udum Butler isolates: the causal agent of pigeonpea Fusarium wilt.

BACKGROUND: Fusarium wilt (Fusarium udum Butler), an important soil-borne disease of pigeonpea [Cajanus cajan (L.)], causes significant yield losses across the major pigeonpea production regions. Widespread and high diversity in F. udum hampers the breeding for pigeonpea wilt resistance. The study aimed to elucidate the pathogenic diversity and distribution of F. udum variants in major pigeonpea growing regions of India. RESULTS: The roving survey was conducted in major pigeonpea-growing states of India to collect the F. udum isolates. Pathogenic variability of 60 F. udum isolates which are selected from diverse geographical locations and pathogenicity test were performed against 11 pigeonpea host differentials cultivars [ICP 8858, ICP 8859, ICP 8862, ICP 8863, ICP 9174, C 11, BDN 1, BDN 2, LRG 30, ICP 2376 and Bahar (ICP 7197)]. The current study indicated distribution of F. udum isolates into nine variants (0, 1, 2, 3, 4, 5, 6, 7 and 8). Variant-2 and 3 were found to be widespread and predominant in most pigeonpea producing regions. Variant-7 (Karnataka) and Variant-8 (Madhya Pradesh and Maharashtra) were found highly virulent, as most of the host differentials were susceptible to these variants. Three host differential cultivars namely ICP 9174, BDN-2 and Bahar (ICP 7197) were found resistant to most of the F. udum isolates. CONCLUSION: The present study generated significant information in terms of variants of F. udum which could be used further for the deployment of location-specific wilt resistant cultivars for optimized disease-management strategies. Study is also useful for development of broad-based wilt resistant cultivars to curtail the possible epidemics.

Melatonin enhances stress tolerance in pigeon pea by promoting flavonoid enrichment, particularly luteolin in response to salt stress.

Melatonin improves plant resistance to multiple stresses by participating in the biosynthesis of metabolites. Flavonoids are an important family of plant secondary metabolites and are widely recognized to be involved in resistance; however, the crosstalk between melatonin and flavonoid is largely unknown. We found that the resistance of pigeon pea (Cajanus cajan) to salt, drought, and heat stresses were significantly enhanced by pre-treatment with melatonin. Combined transcriptome and LC-ESI-MS/MS metabolomics analyses showed that melatonin significantly induced the enrichment of flavonoids and mediated the reprogramming of biosynthetic pathway genes. The highest fold-increase in expression in response to melatonin treatment was observed for the CcF3´H family, which encodes an enzyme that catalyses the biosynthesis of luteolin, and the transcription factor CcPCL1 directly bonded to the CcF3´H-5 promoter to enhance its expression. In addition, salt stress also induced the expression of CcPCL1 and CcF3´H-5, and their overexpression in transgenic plants greatly enhanced salt tolerance by promoting the biosynthesis of luteolin. Overall, our results indicated that pre-treatment of pigeon pea with melatonin promoted luteolin biosynthesis through the CcPCL1 and CcF3´H-5 pathways, resulting in salt tolerance. Our study shows that melatonin enhances plant tolerance to multiple stresses by mediating flavonoid biosynthesis, providing new avenues for studying the crosstalk between melatonin and flavonoids.

Alterations of Primary Metabolites in Root Exudates of Intercropped Cajanus cajan-Zea mays Modulate the Adaptation and Proteome of Ensifer (Sinorhizobium) fredii NGR234.

Legume-cereal intercropping systems, in the context of diversity, ecological function, and better yield have been widely studied. Such systems enhance nutrient phytoavailability by balancing root-rhizosphere interactions. Root exudates (RE) play an important role in the rhizospheric interactions of plant-plant and/or plant-microbiome interaction. However, the influence of the primary metabolites of RE on plant-rhizobia interactions in a legume-cereal intercrop system is not known. To understand the plant communication with rhizobia, Cajanus cajan-Zea mays intercropped plants and the broad host range legume nodulating Ensifer fredii NGR234 as the model plants and rhizobium used respectively. A metabolomics-based approach revealed a clear separation between intercropped and monocropped RE of the two plants. Intercropped C. cajan showed an increase in the myo-inositol, and proline, while intercropped Z. mays showed enhanced galactose, D-glucopyranoside, and arginine in the RE. Physiological assays of NGR234 with the RE of intercropped C. cajan exhibited a significant enhancement in biofilm formation, while intercropped Z. mays RE accelerated the bacterial growth in the late log phase. Further, using label-free proteomics, we identified a total of 2570 proteins of NGR234 covering 50% annotated protein sequences upon exposure to Z. mays RE. Furthermore, intercropped Z. mays RE upregulated bacterioferritin comigratory protein (BCP), putative nitroreductase, IlvD, LeuC, D (branched-chain amino acid proteins), and chaperonin proteins GroEL2. Identification offered new insights into the metabolome of the legume-cereal intercrop and proteome of NGR234-Z. mays interactions that underline the new molecular candidates likely to be involved in the fitness of rhizobium in the intercropping system.

Cajanus cajan shows multiple novel adaptations in response to regular mechanical stress.

Cajanus cajan is one of the least studied crop plants regarding its responses to stress conditions. Regular mechanical stress suppresses plant physiology and growth at the cellular and systemic levels. In the current study, we have explored morphological, physiological, and anatomical adaptations of C. cajan seedlings to regular mechanical stress. Young seedlings of C. cajan were given mechanical stress in the form of touch for fifteen days and observed for various changes. Touch stimuli caused an immediate release of oxidative burst, suppressed plant growth, increased compactness of the stem tissue, and altered the chlorophyll a/b ratio. We have also identified two novel phenotypes; regular touch stimuli affected the nyctinasty movements of the leaves and also affected the root nodule development. We have identified and studied the expression of four putative touch responsive calcium binding genes, TCH gene homologs, in C. cajan using Arabidopsis TCH gene sequences. At an early time point, the expression of two TCH gene homologs (CcTCH1-1 and CcTCH2-2) were found to be upregulated. This study unravels the novel adaptation displayed by C. cajan in response to mechanical stress that can be used as a phenotypic marker for future studies in this plant.

Lignans and Flavonoids from Cajanus cajan (L.) Millsp. and Their α-Glucosidase Inhibitory Activities.

A pair of new lignan conformers (1-2), one new flavonoid glycoside (3), as well as nineteen known compounds were purified from the twigs and leaves of Cajanus cajan (L.) Millsp.. The planar structures of the unknown compounds were determined via NMR and high-resolution mass spectrometry, while their absolute configurations were elucidated via comparison between their experimental and calculated electronic circular dichroism (ECD) values. All the isolated compounds were assayed for their α-glucosidase inhibitory activities. The results demonstrated that compounds 8-12, 15-16, 18-19, 21-22 had strong inhibition activities, with compound 10 (IC50 =0.4±0.21 µM) most active. The structure-activity relationships were preliminarily summarized. Enzyme kinetics showed that compounds 8, 9, 15-16, 18-19, 21-22 were non-competitive inhibitors and compounds 10-12 were anti-competitive ones.

Insulin sensitizer and antihyperlipidemic effects of Cajanus cajan (L.) millsp. root in methylglyoxal-induced diabetic rats.

Cajanus cajan (L.) Millsp., known as pigeon pea, is one of the major grain legume crops of the tropical world. It recognizes as an ethnomedicine to possess various functions, such as helping in healing wound and cancer therapy. We investigated whether 95% ethanol extracts from C. cajan root (EECR) protect against methylglyoxal (MGO)-induced insulin resistance (IR) and hyperlipidemia in male Wistar rats and explored its possible mechanisms. The hypoglycemic potential of EECR was evaluated using α-amylase, α-glucosidase activities, and advanced glycation end products (AGEs) formation. For in vivo study, the rats were divided into six groups and orally supplemented with MGO except for Group 1 (controls). Group 2 was supplemented with MGO only, Group 3: MGO + metformin, Group 4: MGO + Low dose-EECR (L-EECR; 10 mg/kg bw), Group 5: MGO + Middle dose-EECR (M-EECR; 50 mg/kg bw), and Group 6: MGO + High dose-EECR (H-EECR; 100 mg/kg bw). EECR possessed good inhibition of α-glucosidase, α-amylase activities, and AGEs formation (IC50 = 0.12, 0.32, and 0.50 mg/mL), respectively. MGO significantly increased serum levels of blood glucose (GLU), glycosylated hemoglobin, homeostasis model assessment of IR, AGEs, lipid biochemical values, and atherogenic index, whereas EECR decreased these levels in a dose-dependent manner. EECR can also act as an insulin sensitizer, which significantly decreased (47%, P < 0.05) the blood GLU levels after intraperitoneal injection of insulin in the insulin tolerance tests. The hypoglycemic and antihyperlipidemic mechanisms of EECR are likely through several possible pathways including the inhibition of carbohydrate-hydrolyzing enzymes (α-glucosidase and α-amylase) and the enhancement of MGO-trapping effects on inhibition of AGEs formation.

Revisiting the Nutritional, Chemical and Biological Potential of Cajanus cajan (L.) Millsp.

The genus Cajanus (Family: Fabaceae) consists of approximately 37 species, and Cajanus cajan (C. cajan) is a significant member of the genus. It is a commercial legume crop widely grown in sub-tropical and semi-arid tropical areas of the world. C. cajan is well known for its folk medicinal uses to treat various disorders, such as toothache, dizziness, diabetes, stomachache, female ailments and chronic infections. These properties have been linked to the presence of several value-added nutritional and bioactive components. Different solvent extracts from C.cajan (leaves, root, stem and seeds) have been evaluated for their phytochemical and biological activities, namely antioxidant, antimicrobial, antidiabetic, neuroprotective, and anti-inflammatory effects. Taken together, and considering the prominent nutraceutical and therapeutic properties of C. cajan, this review article focuses on the important details including ethnomedicinal uses, chemical composition, biological applications and some other medicinal aspects related to C.cajan nutraceutical and pharmacological applications.

Fusarium solani G6, a novel vitexin-producing endophytic fungus: characterization, yield improvement and osteoblastic proliferation activity.

The study aimed to characterize a novel vitexin-producing endophytic fungus Fusarium solani G6 from Cajanus cajan, improve its capability for producing vitexin and evaluate its osteoblastic proliferation activity. A total of 153 endophytic fungi, classified into 6 genera, were isolated from C. cajan. Among them, only one strain, endophyte G6 identified as Fusarium solani, was found to produce vitexin. After the optimization of fermentation conditions, the highest vitexin yield (18.72 mg/L) for the strain was observed in PDB liquid medium containing 20.54 g/L of glucose and 8.90 g/L of ammonium sulfate, at an initial medium pH of 5.1 and at 28 °C for 6 days of cultivation. Moreover, the fungal vitexin exhibited notable osteoblastic proliferation stimulating activity. A novel vitexin-producing endophytic fungus F. solani G6 was characterized from C. cajan for the first time. The findings highlighted its potential use for large-scale production of vitexin and might have a promising use as therapeutic agent for osteoporosis.

Comparative TMT Proteomic Analysis Unveils Unique Insights into Helicoverpa armigera (Hübner) Resistance in Cajanus scarabaeoides (L.) Thouars.

Pigeonpea [Cajanus cajan (L.) Millspaugh] is an economically important legume playing a crucial role in the semi-arid tropics. Pigeonpea is susceptible to Helicoverpa armigera (Hübner), which causes devastating yield losses. This pest is developing resistance to many commercially available insecticides. Therefore, crop wild relatives of pigeonpea, are being considered as potential sources of genes to expand the genetic base of cultivated pigeonpea to improve traits such as host plant resistance to pests and pathogens. Quantitative proteomic analysis was conducted using the tandem mass tag platform to identify differentially abundant proteins between IBS 3471 and ICPL 87 tolerant accession and susceptible variety to H. armigera, respectively. Leaf proteome were analysed at the vegetative and flowering/podding growth stages. H. armigera tolerance in IBS 3471 appeared to be related to enhanced defence responses, such as changes in secondary metabolite precursors, antioxidants, and the phenylpropanoid pathway. The development of larvae fed on an artificial diet with IBS 3471 lyophilised leaves showed similar inhibition with those fed on an artificial diet with quercetin concentrations with 32 mg/25 g of artificial diet. DAB staining (3,3'-diaminobenzidine) revealed a rapid accumulation of reactive oxygen species in IBS 3471. We conclude that IBS 3471 is an ideal candidate for improving the genetic base of cultivated pigeonpea, including traits for host plant resistance.

Green Extraction of Antioxidant Flavonoids from Pigeon Pea (Cajanus cajan (L.) Millsp.) Seeds and Its Antioxidant Potentials Using Ultrasound-Assisted Methodology.

Pigeon pea is an important pea species in the Fabaceae family that has long been used for food, cosmetic, and other phytopharmaceutical applications. Its seed is reported as a rich source of antioxidants and anti-inflammatory flavonoids, especially isoflavones, i.e., cajanin, cajanol, daidzein, and genistein. In today's era of green chemistry and green cosmetic development, the development and optimization of extraction techniques is increasing employed by the industrial sectors to provide environmentally friendly products for their customers. Surprisingly, there is no research report on improving the extraction of these isoflavonoids from pigeon pea seeds. In this present study, ultrasound-assisted extraction (USAE) methodology, which is a green extraction that provides a shorter extraction time and consumes less solvent, was optimized and compared with the conventional methods. The multivariate strategy, the Behnken-Box design (BBD) combined with response surface methodology, was employed to determine the best extraction conditions for this USAE utilizing ethanol as green solvent. Not only in vitro but also cellular antioxidant activities were evaluated using different assays and approaches. The results indicated that USAE provided a substantial gain of ca 70% in the (iso)flavonoids extracted and the biological antioxidant activities were preserved, compared to the conventional method. The best extraction conditions were 39.19 min with a frequency of 29.96 kHz and 63.81% (v/v) aqueous ethanol. Both the antioxidant and anti-aging potentials of the extract were obtained under optimal USAE at a cellular level using yeast as a model, resulting in lower levels of malondialdehyde. These results demonstrated that the extract can act as an effective activator of the cell longevity protein (SIR2/SIRT1) and cell membrane protector against oxidative stress. This finding supports the potential of pigeon pea seeds and USAE methodology to gain potential antioxidant and anti-aging (iso)flavonoids-rich sources for the cosmetic and phytopharmaceutical sectors.

Genomic characterization of ZIP genes in pigeonpea (CcZIP) and their expression analysis among the genotypes with contrasting host response to pod borer.

Zinc (Zn) is a vital micronutrient from the perspective of biofortification and biotic stress endurance in pigeonpea. The ZIP transporters with domain (Pfam: PF02535) regulate uptake and transport of metal ions, including Zn, in consonance with plant metal homeostasis. Genome-wide analysis in pigeonpea identified 19 non-redundant members of ZIP family (CcZIP) that were analyzed for gene structure, conserved motifs and homology besides other structural and biochemical parameters. Intra-specific as well as the inter-specific phylogenetic relationships of these 19 CcZIPs were elucidated by comparison with ZIP proteins of Arabidopsis thaliana, Medicago truncatula, Phaseolus vulgaris and Glycine max. In addition to gene structure, the cis-regulatory elements (CREs) in the promoter region were also identified. It revealed several stress responsive CREs that might be regulatory for differential expression of CcZIP proteins. Expression analysis showed that both CcZIP3 and CcZIP15, having zinc deficiency responsive element, up-regulated in the reproductive leaf tissues and down-regulated in matured green pods of the pod borer resistant genotypes with higher zinc content. Alternately, the expression of CcZIP6 and CcZIP13 was higher in matured green pods than reproductive leaves of the resistant genotypes. These findings on differential expression indicate the possible role of these CcZIPs on the mobilization of Zn from leaves to pods, phloem loading and unloading, and higher accumulation of seed zinc in pod borer resistant genotypes used in this study. Further functional characterization of CcZIP genes could shed light on their role in bio-fortification and genetic improvement to inhibit the pod borer herbivory in pigeonpea. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01111-1.

Effects of Cajanus cajan (L.) millsp. roots extracts on the antioxidant and anti-inflammatory activities.

Cajanus cajan (L.) Millsp., also named pigeon pea, is widely grown in the tropics and the subtropics. C. cajan roots (CR) and ribs stewed in hot water have been used as a traditional medicine in various cultures to treat diabetes. The purpose of this study was to determine the functional components of hot water (WCR) and 50%, 95% ethanol extracts (EECR50 and EECR95) from CR, then evaluating their antioxidant and anti-inflammatory effects. The results indicated that EECR95 had higher polyphenol, especially the isoflavones (e.x. daidzein, genistein, and cajanol) than those of the other extracts, and it also exhibited the most potent anti-oxidative activities by in vitro antioxidant assay. In the lipopolysaccharide-stimulated RAW 264.7 cells, we found that EECR95 significantly decreased intracellular reactive oxygen species and significantly enhanced the activities of superoxide dismutase and catalase. Mechanism studies showed that EECR95 mainly activated nuclear factor (NF) erythroid 2-related factor 2/antioxidant protein heme oxygenase-1 and inhibited nuclear factor kappa B (NF-κB) signaling pathway, and thus exhibited antioxidant and anti-inflammatory effects. Overall, this study suggests that CR may have the potential to be developed as a biomedical material and that genistein, which has relatively high uptakes (3.44% for the pure compound and 1.73% for endogenous genistein of EECR95) at 24 h of incubation with RAW 264.7 cells, could be the main active component of CR.

Root colonization by heavy metal resistant Enterobacter and its influence on metal induced oxidative stress on Cajanus cajan.

BACKGROUND: Heavy metal resistant bacterium Enterobacter sp. C1D was evaluated for cadmium (Cd) mediated exopolysaccharide production, biofilm formation and legume root colonization ability under Cd stress to alleviate metal induced stress. RESULTS: The plant was sensitive to Cd (IC50 3-4 µg mL-1 ), whereas the bacterium showed high Cd tolerance (MIC99 120 µg mL-1 ). Confocal laser scanning microscopy of the Cajanus cajan roots showed heavy loads of green fluorescence protein labelled Enterobacter sp. C1D on the surface of plant root, specifically at the point of root hair/lateral root formation along with cortex, even under metal stress. The root colonizing ability of Enterobacter sp. C1D was not affected by the presence of Rhizobium and the bacteria could be observed after 30 days of incubation in soil. Various plant growth parameters, antioxidant metabolites and oxidative stress indicator were significantly influenced by bacterial treatment, which, overall, reduced the adverse effect of Cd. CONCLUSION: Heavy metal tolerant bacteria may be a good choice for the development of biofertilizers and may work well with the native soil microbes such as Rhizobium under the metal polluted soil. © 2019 Society of Chemical Industry.

Spray drying encapsulation of a native plant extract rich in phenolic compounds with combinations of maltodextrin and non-conventional wall materials.

Crotalaria longirostrata (chipilin) leaves contain phenolic compounds with antioxidant activity. These phenolic compounds, however, could easily degrade after extraction. Microencapsulation is a possible solution for avoiding this degradation. Frequently, microencapsulation is carried out using conventional encapsulating agents. The aim of this work was to evaluate the effect of several non-conventional encapsulating agents on microencapsulation by spray drying of phenolic compounds from chipilin, stability and release of phenolic compounds were also studied. Maltodextrin (MD), gum Arabic (GA), soy protein (SP), cocoa shell pectin (CSP), and protein (PC), as well as the gum (GC) of Cajanus cajan seeds were used. Different blends of these matrixes containing phenolic compounds from chipilin leaves were spray dried at 120 °C. After drying, the yield and microencapsulation efficiency were determined. All results were analyzed by an ANOVA test (p < 0.05). The release kinetics of phenolic compounds were modeled using zero, first-order, Higuchi and Korsmeyer-Peppas models. The R2 was calculated for each model. The blends of encapsulating agents allowed the formation of an efficient polymer matrix with yields between 46 and 64% and microencapsulation efficiency between 65 and 92%. Results show that maltodextrin with soy protein allowed the highest (92%) microencapsulation efficiency, although maltodextrin and cocoa shell pectin were more effective protective agents, showing greater stability. The Korsmeyer-Peppas model was the best in predicting the phenolic compounds release with R2 values higher than 98%. The stability time for microcapsules with MD-CSP was 8.88 years and 1.43 years at 4 °C and 30 °C, respectively.

Development of sequence-based markers for seed protein content in pigeonpea.

Pigeonpea is an important source of dietary protein to over a billion people globally, but genetic enhancement of seed protein content (SPC) in the crop has received limited attention for a long time. Use of genomics-assisted breeding would facilitate accelerating genetic gain for SPC. However, neither genetic markers nor genes associated with this important trait have been identified in this crop. Therefore, the present study exploited whole genome re-sequencing (WGRS) data of four pigeonpea genotypes (~ 12X coverage) to identify sequence-based markers and associated candidate genes for SPC. By combining a common variant filtering strategy on available WGRS data with knowledge of gene functions in relation to SPC, 108 sequence variants from 57 genes were identified. These genes were assigned to 19 GO molecular function categories with 56% belonging to only two categories. Furthermore, Sanger sequencing confirmed presence of 75.4% of the variants in 37 genes. Out of 30 sequence variants converted into CAPS/dCAPS markers, 17 showed high level of polymorphism between low and high SPC genotypes. Assay of 16 of the polymorphic CAPS/dCAPS markers on an F2 population of the cross ICP 5529 (high SPC) × ICP 11605 (low SPC), resulted in four of the CAPS/dCAPS markers significantly (P < 0.05) co-segregated with SPC. In summary, four markers derived from mutations in four genes will be useful for enhancing/regulating SPC in pigeonpea crop improvement programs.