Cowpea lipid transfer protein 1 regulates plant defense by inhibiting the cysteine protease of cowpea mosaic virus.

Many virus genomes encode proteases that facilitate infection. The molecular mechanism of plant recognition of viral proteases is largely unexplored. Using the system of Vigna unguiculata and cowpea mosaic virus (CPMV), we identified a cowpea lipid transfer protein (LTP1) which interacts with CPMV-encoded 24KPro, a cysteine protease, but not with the enzymatically inactive mutant 24KPro(C166A). Biochemical assays showed that LTP1 inhibited 24KPro proteolytic cleavage of the coat protein precursor large coat protein-small coat protein. Transient overexpression of LTP1 in cowpea reduced CPMV infection, whereas RNA interference-mediated LTP1 silencing increased CPMV accumulation in cowpea. LTP1 is mainly localized in the apoplast of uninfected plant cells, and after CPMV infection, most of the LTP1 is relocated to intracellular compartments, including chloroplast. Moreover, in stable LTP1-transgenic Nicotiana benthamiana plants, LTP1 repressed soybean mosaic virus (SMV) nuclear inclusion a protease activity, and accumulation of SMV was significantly reduced. We propose that cowpea LTP1 suppresses CPMV and SMV accumulation by directly inhibiting viral cysteine protease activity.

Early agriculture and crop transitions at Kakapel Rockshelter in the Lake Victoria region of eastern Africa.

The histories of African crops remain poorly understood despite their contemporary importance. Integration of crops from western, eastern and northern Africa probably first occurred in the Great Lakes Region of eastern Africa; however, little is known about when and how these agricultural systems coalesced. This article presents archaeobotanical analyses from an approximately 9000-year archaeological sequence at Kakapel Rockshelter in western Kenya, comprising the largest and most extensively dated archaeobotanical record from the interior of equatorial eastern Africa. Direct radiocarbon dates on carbonized seeds document the presence of the West African crop cowpea (Vigna unguiculata (L.) Walp) approximately 2300 years ago, synchronic with the earliest date for domesticated cattle (Bos taurus). Peas (Pisum sativum L. or Pisum abyssinicum A. Braun) and sorghum (Sorghum bicolor (L.) Moench) from the northeast and eastern African finger millet (Eleusine coracana (L.) Gaertn.) are incorporated later, by at least 1000 years ago. Combined with ancient DNA evidence from Kakapel and the surrounding region, these data support a scenario in which the use of diverse domesticated species in eastern Africa changed over time rather than arriving and being maintained as a single package. Findings highlight the importance of local heterogeneity in shaping the spread of food production in sub-Saharan Africa.

Seeds of nonhost species as sources of toxic compounds for the cowpea weevil Callosobruchus maculatus (F.).

Cowpea weevil, Callosobruchus maculatus, is the primary pest of stored cowpea seeds. The management of this infestation currently relies on insecticides, resulting in environmental pollution and selection of insecticide-resistant pests. Consequently, research efforts are being devoted to identify natural insecticides as sustainable and environment friendly alternatives for the control of C. maculatus. In this study, we explore the toxic effects of the nonhost seeds Parkia multijuga, Copaifera langsdorffii, Ormosia arborea, Amburana cearensis, Lonchocarpus guilleminianus, Sapindus saponaria, and Myroxylon peruiferum, on the cowpea weevil C. maculatus. Notably, all nonhost seeds led to reductions between 60 and 100% in oviposition by C. maculatus females. Additionally, the larvae were unable to penetrate the nonhost seeds. Artificial seeds containing 0.05% to 10% of cotyledon flour were toxic to C. maculatus larvae. Approximately 40% of larvae that consumed seeds containing 0.05% of O. arborea failed to develop, in contrast to control larvae. Proteomic analysis of A. cearensis and O. arborea seeds identify revealed a total of 371 proteins. From those, 237 are present in both seeds, 91 were exclusive to O. arborea seeds, and 43 were specific to A. cearensis seeds. Some of these proteins are related to defense, such as proteins containing the cupin domain and 11S seed storage protein. The in silico docking of cupin domain-containing proteins and 11S storage protein with N-acetylglucosamine (NAG)4 showed negative values of affinity energy, indicating spontaneous binding. These results showed that nonhost seeds have natural insecticide compounds with potential to control C. maculatus infestation.

Phytoremediation of crude oil-contaminated soil using Vigna Unguiculata and associated rhizosphere bacteria.

Persistent crude oil contamination poses a significant environmental challenge. In this study, the efficacy of Vigna unguiculata (L.) and associated rhizospheric microorganisms in remediating crude oil-contaminated soil within a microcosm setting was investigated. A randomized block design was employed, and soil samples were subjected to varying degrees of contamination: 0% (UR), 2.5% (CR2), 5.0% (CR5), 7.5% (CR7), and 10.0% (CR10) w/w crude oil. The investigation aimed to assess the potential of Vigna unguiculata (L.) in mitigating crude oil contamination across these defined contamination gradients. The plant growth and crude oil removal were monitored concurrently post-emergence. Plant emergence and growth were significantly affected due to contamination, especially among plants in CR5 and CR10. The bacterial population was higher in the rhizosphere, and the treatments with lower hydrocarbon contamination. It was shown that plant density encouraged the growth of bacterial communities. Significant reduction in soil TPH was observed in CR2 (76.61%) and CR7 (65.88%). There was a strong correlation between plant growth and oil-utilizing bacterial population (r2 = 0.966) and plant growth and hydrocarbon reduction (r2 = 0.956), signifying the role of plant-bacterial synergy. Saturate fractions (C30 - C32) were significantly degraded to lower molecular weight compounds (C11 - C14). Except in CR5 and CR10, the remediation within the cowpea rhizosphere was effective even at regulatory standards. Understanding the rhizosphere ecological dynamics would further highlight the role the bacteria played; hence, it is recommended.

The present study established a direct link between bacterial-plant interaction and biodegradation of crude oil. It extensively explored the nature of the degradation and also the fate of the residual oil. The present study achieved high rate of TPH removal within 12 weeks using cowpea alone as against the several previous reports that used other stimulants.

Antithrombotic and anticariogenic activity of peptide fractions from cowpea (Vigna unguiculata) protein hydrolysates.

BACKGROUND: Protein-derived peptide fractions can play a key role in the physiological and metabolic regulation and modulation of the body, which suggests that they could be used as functional ingredients to improve health and to reduce the risk of disease. This work aimed to evaluate the in vitro antithrombotic and anticariogenic bioactivity of hydrolysates and protein fractions obtained from cowpea (Vigna unguiculata) by biocatalysis. RESULTS: Cowpea protein concentrate was hydrolyzed by sequential action with two enzyme systems, Pepsin-Pancreatin or Alcalase-Flavourzyme. There was extensive enzymatic hydrolysis, with degrees of hydrolysis of 34.94% and 81.43% for Pepsin-Pancreatin and Alcalase-Flavourzyme, respectively. The degree of hydrolysis for the control treatments, without the addition of the enzymes Pepsin-Pancreatin and Alcalase-Flavourzyme was 1.1% and 1.2%, respectively. The hydrolysates were subjected to fractionation by ultrafiltration, with five cut-off points according to molecular weight (<1, 1-3, 3-5, 5-10 and >10 kDa). The Alcalase-Flavourzyme hydrolysate led to 100% inhibition of platelet aggregation, while the Pepsin-Pancreatin hydrolysate showed 77.41% inhibition, but this was approximately 100% in the ultrafiltered fractions. The highest anticariogenic activity was obtained with the Pepsin-Pancreatin system, with 61.55% and 56.07% for calcium and phosphorus demineralization, respectively. CONCLUSION: Hydrolysates and their peptide fractions from Vigna unguiculata exhibited inhibition of platelet aggregation and protection of tooth enamel and have the potential for use in the development of functional products with beneficial health effects. © 2024 Society of Chemical Industry.

Signatures of plant defense response specificity mediated by herbivore-associated molecular patterns in legumes.

Chewing herbivores activate plant defense responses through a combination of mechanical wounding and elicitation by herbivore-associated molecular patterns (HAMPs). HAMPs are wound response amplifiers; however, specific defense outputs may also exist that strictly require HAMP-mediated defense signaling. To investigate HAMP-mediated signaling and defense responses, we characterized cowpea (Vigna unguiculata) transcriptome changes following elicitation by inceptin, a peptide HAMP common in Lepidoptera larvae oral secretions. Following inceptin treatment, we observed large-scale reprogramming of the transcriptome consistent with three different response categories: (i) amplification of mechanical wound responses, (ii) temporal extension through accelerated or prolonged responses, and (iii) examples of inceptin-specific elicitation and suppression. At both early and late timepoints, namely 1 and 6 h, large sets of transcripts specifically accumulated following inceptin elicitation. Further early inceptin-regulated transcripts were classified as reversing changes induced by wounding alone. Within key signaling- and defense-related gene families, inceptin-elicited responses included target subsets of wound-induced transcripts. Transcripts displaying the largest inceptin-elicited fold changes included transcripts encoding terpene synthases (TPSs) and peroxidases (POXs) that correspond with induced volatile production and increased POX activity in cowpea. Characterization of inceptin-elicited cowpea defenses via heterologous expression in Nicotiana benthamiana demonstrated that specific cowpea TPSs and POXs were able to confer terpene emission and the reduced growth of beet armyworm (Spodoptera exigua) herbivores, respectively. Collectively, our present findings in cowpea support a model where HAMP elicitation both amplifies concurrent wound responses and specifically contributes to the activation of selective outputs associated with direct and indirect antiherbivore defenses.

Diallel analysis of cowpea (Vigna unguiculata (L.) Walp.) genotypes under water deficit stress.

Combining ability is referred to as the hybridization value of the parental genotypes involved in the crossing to develop hybrids. The best parents are selected through combining ability methods and subsequently used to produce high yielding and resistant hybrids. Thus, the objectives of this study were to (i) understand the nature and action of genes controlling water deficit tolerance, and (ii) identify superior genotypes from the genetic breadth provided by hybridization in cowpea. Twenty-four genotypes were subjected to normal irrigation and water deficit condition to examine combining ability, genotypic and phenotypic correlations for traits directly related to water deficit (proline and chlorophylls), grain yield and yield components. The results showed the presence of the action of additive and non-additive genes under both water regime conditions. However, there was the predominance of the action of additive genes for most of the traits studied under both conditions. The parents KVX61-1, IT06K242-3, IT07K-211-1-8, Kpodjiguèguè, IT99K-573-1-1, Tawa and IT97K-206-1-1 were observed to be good general combiners for proline content, chlorophyll content and traits associated with yield, while KVX61-1 × KVX396-18, IT06K242-3 × KVX396-18, IT07K-211-1-1 × KVX396-18, Kpodjiguèguè x KVX396-18, KVX61 -1 × IT97K-206-1-1, IT06K242-3 × IT97K-206-1-1, IT07K-211-1-1 × IT97K-206-1-1 and Kpodjiguèguè x IT97K-206-1-1 were proven to be the best specific combiners for traits directly related to water deficit tolerance and yield. It should be noted that number of days to pod maturity, pod length, number of pods per plant and weight of hundred seeds were highly heritable traits in this study.

Comprehensive genomic analyses of Vigna unguiculata provide insights into population differentiation and the genetic basis of key agricultural traits.

Vigna unguiculata is an important legume crop worldwide. The subsp. sesquipedalis and unguiculata are the two major types grown; the former is mainly grown in Asia to produce fresh pods, while the latter is mainly grown in Africa to produce seeds. Here, a chromosome-scale genome for subsp. sesquipedalis was generated by combining high-fidelity (HiFi) long-read sequencing with high-throughput chromosome conformation capture (Hi-C) technology. The genome size for all contigs and N50 were 594 and 18.5 Mb, respectively. The Hi-C interaction map helped cluster 91% of the contigs into 11 chromosomes. Genome comparisons between subsp. sesquipedalis and unguiculata revealed extensive genomic variations, and some variations resulted in gene loss. A germplasm panel with 315 accessions of V. unguiculata was resequenced, and a genomic variation map was constructed. Population structure and phylogenetic analyses suggested that subsp. sesquipedalis originated from subsp. unguiculata. Highly differentiated genomic regions were also identified, and a number of genes functionally enriched in adaptations were located in these regions. Two traits, pod length (PL) and pod width (PW), were observed for this germplasm, and genome-wide association analysis of these traits was performed. The quantitative trait loci (QTLs) for these two traits were identified, and their candidate genes were uncovered. Interestingly, genomic regions of PL QTLs also showed strong signals of artificial selection. Taken together, the results of this study provide novel insights into the population differentiation and genetic basis of key agricultural traits in V. unguiculata.

Not just passengers, but co-pilots! Non-rhizobial nodule-associated bacteria promote cowpea growth and symbiosis with (brady)rhizobia.

AIMS: To isolate and characterize non-rhizobial nodule-associated bacteria (NAB) from cowpea root-nodules regarding their performance of plant-growth-promoting mechanisms and their ability to enhance cowpea growth and symbiosis when co-inoculated with bradyrhizobia. METHODS AND RESULTS: Sixteen NAB were isolated, identified, and in vitro evaluated for plant growth promotion traits. The ability to promote cowpea growth was analyzed when co-inoculated with Bradyrhizobium pachyrhizi BR 3262 in sterile and non-sterile substrates. The 16S rRNA gene sequences analysis revealed that NAB belonged to the genera Chryseobacterium (4), Bacillus (3), Microbacterium (3), Agrobacterium (1), Escherichia (1), Delftia (1), Pelomonas (1), Sphingomonas (1), and Staphylococcus (1). All strains produced different amounts of auxin siderophores and formed biofilms. Twelve out of the 16 strains carried the nifH, a gene associated with nitrogen fixation. Co-inoculation of NAB (ESA 424 and ESA 29) with Bradyrhizobium pachyrhizi BR 3262 significantly promoted cowpea growth, especially after simultaneous inoculation with the three strains. CONCLUSIONS: NAB are efficient cowpea growth promoters and can improve the efficiency of the symbiosis between cowpea and the N2-fixing microsymbiont B. pachyrhizi BR 3262, mainly under a specific triple microbial association.

Vigna unguiculata L. Walp. Leaves as a Source of Phytochemicals of Dietary Interest: Optimization of Ultrasound-Assisted Extraction and Assessment of Traditional Consumer Habits.

Vigna unguiculata L. Walp. is an African crop spread worldwide mainly for pulses production. Despite being a neglected and under-utilized food, cowpea leaves are a rich source of phytochemicals and micronutrients. The aim of the work is to characterize the phytochemical composition of cowpea leaves by an optimized ultrasound-assisted extraction (USAE) and to compare raw and boiled leaves. A three-level factorial design (Box-Behnken) was employed for the optimization of the USAE considering three different parameters (% ethanol, drug-to-solvent ratio, and number of cycles). The optimized extracts were characterized by LC/MS/MS. Finally, leaves were boiled at 100 °C for 30 min to simulate traditional cooking procedures and compared to raw leaves. The best extraction condition was EtOH/H2 O 1 : 2 v/v, drug to solvent ratio 1 : 47 w/v, and 3 extraction cycles. The phytochemicals identified mainly belong to the family of phenolic acids, flavonoids, terpenoids, and alkaloids. Boiled leaves revealed a significant loss of most phytochemicals and a net decrease of their antioxidant activity compared to the raw ones. The results highlight the potential nutraceutical value of cowpea leaves whilst the impoverishment triggered by traditional consumer habits pushes the need to evaluate alternative cooking procedures helpful in the maintenance of their phytochemical properties.

GC/MS and LC/MS Phytochemical Analysis of Vigna unguiculata L. Walp Pod.

Vigna unguiculata (L. Walp) or Cowpea pod methanolic extracts phytochemical analysis, total phenolic content (TPC), and secondary metabolite profiling were determined using gas chromatography-mass spectrometry (GC/MS) and liquid chromatography-mass spectrometry (LC/MS) analysis. GC/MS analysis revealed twenty compounds in the extract, while LC/MS analysis identified twenty-four compounds. GC/MS chromatogram analysis suggested the presence of opioid α-N-Normethadol a major constituent found in methanolic extract and fatty acid esters carotenoid is found second major constituent. LC/MS chromatogram and the mass spectral analysis demonstrated the presence of flavonoids, carotenoids, and alkaloids as major phytochemicals. We investigated the antibacterial, anti-fungal, and anti-oxidant activity of pod methanolic extract. The extract was found equally effective against E. coli, S. pyogenes, and P. aeruginosa with MIC 100 µg/mL similar to the standard Ampicillin (MIC 100 µg/mL). C. albicans were found to be most susceptible to Vign unguiculata pods methanolic extract with a MIC of 250 µg/mL. The pod extract showed significant DPPH scavenging activity (IC50 =78.38±0.15) which suggests its antioxidant potential.

First report of powdery mildew on Vigna unguiculata caused by Podosphaera xanthii in China.

Vigna unguiculata belongs to the Legume family, and is an annual twining, herbaceous vine plant, which is native to Africa. V. unguiculata is the most economically beneficial type of off-season vegetables in Hainan, China because of its rich in nutrients such as protein, minerals, dietary fiber, and vitamins (Jayathilake et al. 2018). In April 2022, typical powdery mildew infection was observed on V. unguiculata leaves in Haikou, Hainan Province, China (20°3'40.428"N, 110°19'45.217"E). More than 70% leaves of 13 V. unguiculata plants displayed severe powdery mildew disease. The diseased leaves at first exhibited white rounded irregular patches, which gradually enlarged, fused and covered all the leaf as well as stems. Edges of the infected leaves crinkled upwards, and the leaves often fell off the plants at the late infection stage. On the infected leaves, many conidiophores and dense mycelium were observed by microscopic analysis. Hyphae were septate, branched, epigenous, and flexuous to straight. Hyphal appressoria were indistinct or slightly nipple-shaped, and the haustoria developed were in the shape of oval-sphere and 9 to 11µm long. Foot cells of conidiophores were straight, cylindrical, and measured 43 to 70 × 10 to 12 µm. The conidiophores arising straightly from a hyphal cell, were measured 168 to 252 (mean = 204) µm in length and produced 6 to 9 immature conidia in each chain. Conidia were ovate, pyriform or barrel-shaped, with fibrosin bodies, and measured 26 to 32 (mean = 29.4) × 16 to 20 (mean = 18.6) µm. The chasmothecia was not found in all samples. These morphological characteristics were typical of the conidial stage of the powdery mildew Podosphaera xanthii of genus Podosphaera (Braun and Cook 2012). To further confirm the identity of this causal fungus, the internal transcribed spacer (ITS) region, and the partial sequence of large subunit ribosomal RNA gene (28S rRNA), were amplified with primer pairs ITS1/ ITS4 (White et al. 1990) and NL1/NLP2 (Mori et al. 2000) from extracted genomic DNA. The obtained 563-bp ITS region and 715-bp 28S rRNA gene sequences were deposited in GenBank (ITS, OQ415534; 28S rRNA, OQ415545.1), and were compared with BLAST analysis in the GenBank nr database. The results revealed that the ITS region sequence was 99.82% identity with P. xanthii isolate HUVU-08 (MH143485.1), and the 28S rRNA gene partial sequence was 100% identity with P. xanthii isolate XHL1 (MK357442.1). On the basis of the morphological characteristics and sequence analysis, this fungus was identified as P. xanthii. Pathogenicity tests were performed by gently brushing conidia onto the leaves of six healthy potted V. unguiculata plants. Six non-inoculated plants were used as control. All plants were maintained in a greenhouse at 26 ± 2°C. After 2 weeks inoculation, similar symptoms were observed in the inoculated plants, whereas no symptoms occurred on the control plants. By microscopic observation, the fungus present on the inoculated plants was morphologically identical to those on originally diseased plants. Furthermore, ITS and 28S rRNA sequences of the re-isolated fungus individually displayed 100% identity with OQ415534 and OQ415545.1. So far, although powdery mildew disease caused by P. xanthii on different plants including Sigesbeckia orientalis (Mukhtar et al. 2022), Vigna radiata (Sheu et al. 2021), Cosmos bipinnatus (Kong et al. 2023), Verbena brasiliensis (Luecke et al. 2020), Cucurbita ficifolia (Choi et al. 2022), Glandularia tenera (Pei et al. 2023) and Verbena bonariensis (Choi et al. 2023) have been reported, to our knowledge, this is the first report of powdery mildew caused by P. xanthii on V. unguiculata in Hainan, China, which seriously threatens the utilization of V. unguiculata on off-season vegetables industry.

First Report of 16SrII Group Related Phytoplasma Associated with Witches'-broom Disease on Cowpea (Vigna unguiculata) in Hainan Province, China.

Cowpea (Vigna unguiculata L.), a significant vegetable crop in China, holds particular prominence in the tropical island of Hainan. This region serves as the primary production area for the winter cultivation of cowpea. Phytoplasmas are an idiopathic parasitic pathogen and cannot be cultured in vitro. It is mainly transmitted by the insect vectors with the piercing and sucking mouthparts, such as leafhoppers, plant hoppers, and psyllids. (Kumari et al. 2019). On September 11, 2023, typical characteristics of phytoplasma diseases on cowpeas were observed in the experimental base of Hainan Academy of Agricultural Sciences (20°0'38.6964″N, 110°21'35.4024″E, Haikou City, Hainan Province, China), including reduced leaf size, chlorosis, and the development of broom-like branch deformities reminiscent, as depicted in Figure 1. At the same time, we found a large number of leafhoppers near the diseased plants, and we speculated that leafhoppers are the insect carriers that spread the disease. Following an on-site investigation, it was determined that the disease incidence ranges from 10% to 15%, leading to a consequential decrease of about 10% in yield, which is a potential disease that seriously threatens the cowpea industry in Hainan. Ten disease and healthy samples were meticulously collected and subsequently preserved at -80°C within the laboratory refrigerator. Three disease samples denoted as HNNKY-1, HNNKY-2, and HNNKY-3, were randomly chosen, and total DNA extraction was carried out employing the NuClean Plant Genomic DNA Kit (CWBIO, Taizhou, China), while three healthy samples were randomly selected as control. The 16S rRNA gene was amplified by PCR using the primer pairs P1/P7 (Schneider et al. 1995) and R16F2n / R16R2 (Lee et al. 1993) and the secA gene was amplified by PCR using the primer pairs secAfor1/secArev3 (Hodgetts et al. 2008). After agarose gel electrophoresis analysis, no DNA fragments were observed in the healthy leaf samples, whereas all three disease samples yielded amplification products. The PCR products were subsequently sequenced by Hainan Nanshan Biotech Co., Ltd., Haikou, China. After sequence analysis, it was found that the 16S rRNA gene and secA gene sequences HNNKY-1, HNNKY-2, and HNNKY-3 were identical to each other. We selected two gene sequences of strain HNNKY-3 to submission to the GenBank database, The length of the 16S rRNA gene sequence is 1193 base pairs, identified by the accession number OR666421, while the secA gene sequence is 825 base pairs in length, associated with the accession number OR661282. The phytoplasma strain HNNKY-3 was named 'Vigna unguiculata' witches'-broom phytoplasma. A BLAST analysis of the 16S rRNA gene revealed that strain HNNKY-3 displayed a 100% sequence match with 'Emilia sonchifolia' witches'-broom phytoplasma (MT420682), Peanut witches'-broom phytoplasma (OR239773), and 'Raphanus sativus' witches'-broom phytoplasma (OK491387). All of these phytoplasmas were classified within the 16SrII group. Based on the BLAST analysis of partial secA gene sequences, it was discerned that sequence homogeneity ranged from 99.27% to 99.74% among the studied sequences. These sequences were collectively classified as members of the 16SrII group. In addition, a phylogenetic tree was constructed by MEGA 11 (version 11.0.13) based on the 16Sr RNA gene and secA gene by the neighbor-joining method (Tamura et al. 2004). The results demonstrated the clustering of HNNKY-3 phytoplasma strains within the 16SrII group, as illustrated in Figures 2 and 3. A virtual RFLP analysis based on the 16S rRNA gene fragment of HNNKY-3 was conducted using the interactive online phytoplasma classification tool, iPhyClassifier (Zhao et al. 2009). The results indicated that the phytoplasma strain was the same as the reference pattern of the onion yellows phytoplasma of 16SrII-A (GenBank accession: L33765), and the similarity coefficient was 1.00. To best of our knowledge, this is the inaugural documentation of 16SrII Group-related phytoplasma infecting cowpea in Hainan, China, and lays the groundwork for further research on the dissemination of cowpea phytoplasma disease within China.

Isolation, Structural Characteristics Analysis of a Vigna unguiculata Polysaccharide VUP80-3 and Its Protective Effect on GES-1 Cells In Vitro.

Cowpea (Vigna unguiculata) is one of the main edible legume vegetables in China, and it can improve spleen and stomach function. A polysaccharide component (VUP80-3) has been isolated from V. unguiculata in this study. The average molecular weight of VUP80-3 is 6.43 × 104 Da, and the main monosaccharide group is glucose. The mass ratio of monosaccharide groups in the polysaccharide was glucose:galactose:arabinose:rhamnose:xylose:mannose:fucose = 152.36:24.50:16.53:8.13:1.26:0.97:0.82. NMR analysis showed that VUP80-3 has →4)-α-D-Galp (1→ and →4)-α-D-Glcp(1→ main chain and →3,4)-ß-D-Glcp(1→, →4,6)-α-D-Glcp(1→ branch chains, and the terminal sugar is α-D-Glcp(1→. Biological activity test results showed that VUP80-3 at 1000 µg·mL-1 significantly increased the activity of ethanol injured GES-1 cells (p < 0.01) and significantly reduced reactive oxygen species (ROS) in ethanol injured GES-1 cells and inflammatory factors (IL-8, IL-1ß and TNF-α,) in GES-1 cells. This compound also reduced the apoptosis rate (p < 0.05), thereby significantly reducing the oxidative damage caused by ethanol in GES-1 cells. Therefore, VUP80-3 is a potential drug to protect the gastric mucosa from damage.

Polymeric formulations of liquid inoculants with rhizobia exopolysaccharides increase the survival and symbiotic efficiency of elite Bradyrhizobium strains.

We studied the survival of four elite strains of Bradyrhizobium in liquid inoculants with three formulations with exopolysaccharides extracted from other rhizobia genera, and the symbiotic efficiency of these elite strains with soybean and cowpea in a greenhouse. For that purpose, we verified the effectiveness of formulations for maintaining the cell viability of strains by counting the colony-forming units (CFU) per milliliter of the liquid inoculants with formulations after 90 days. For survival of the soybean inoculant strains, 29W and CPAC15, the largest number of CFU (> 1010 mL-1) after 90 days was observed in the PEPS formulation. For the cowpea inoculant strains, INPA3-11B and UFLA3-84, the REPS1 formulation had the largest number of CFU (> 1010 mL-1) after 90 days. The symbiotic efficiency of the PEPS formulation, followed by REPS2, was higher than that shown by the commercial inoculant in soybean. For cowpea, the three formulations with EPS, especially REPS1, showed symbiotic efficiency better than that of the commercial inoculant.

Thermal Shift Assay as a Tool to Evaluate the Release of Breakdown Peptides from Cowpea ß-Vignin during Seed Germination.

The present work aimed to characterize the molecular relationships between structure and function of the seed storage protein ß-vignin, the vicilin storage protein of cowpea (Vigna unguiculata, l. Walp) seeds. The molecular characterization of ß-vignin was carried out firstly by assessing its thermal stability, under different conditions of pH and ionic strength, by thermal shift assay (TSA) using SYPRO Orange fluorescent dye. Secondly, its aggregation propensity was evaluated using a combination of chromatographic and electrophoretic techniques. Two forms of ß-vignin were considered: the native form purified from mature quiescent seeds, and a stable breakdown intermediate of 27 kDa produced while seeds germinate. TSA is a useful tool for determining and following over time the structural changes that occur to the protein during germination. The main result was the molecular characterization of the 27 kDa intermediate breakdown polypeptide, which, to the best of our knowledge, has never been described before. ß-vignin seems to retain its trimeric conformation despite the evident degradation of its polypeptides.

The roles of photorespiration and alternative electron acceptors in the responses of photosynthesis to elevated temperatures in cowpea.

We explored the effects, on photosynthesis in cowpea (Vigna unguiculata) seedlings, of high temperature and light-environmental stresses that often co-occur under field conditions and can have greater impact on photosynthesis than either by itself. We observed contrasting responses in the light and carbon assimilatory reactions, whereby in high temperature, the light reactions were stimulated while CO2 assimilation was substantially reduced. There were two striking observations. Firstly, the primary quinone acceptor (QA ), a measure of the regulatory balance of the light reactions, became more oxidized with increasing temperature, suggesting increased electron sink capacity, despite the reduced CO2 fixation. Secondly, a strong, O2 -dependent inactivation of assimilation capacity, consistent with down-regulation of rubisco under these conditions. The dependence of these effects on CO2 , O2 and light led us to conclude that both photorespiration and an alternative electron acceptor supported increased electron flow, and thus provided photoprotection under these conditions. Further experiments showed that the increased electron flow was maintained by rapid rates of PSII repair, particularly at combined high light and temperature. Overall, the results suggest that photodamage to the light reactions can be avoided under high light and temperatures by increasing electron sink strength, even when assimilation is strongly suppressed.

First complete genome sequence of an isolate of cowpea severe mosaic virus from South America.

In this study, the complete nucleotide sequence of a Brazilian isolate of cowpea severe mosaic virus (CPSMV) is presented for the first time. To date, the CPSMV-DG isolate, from the USA, is the only one with the complete known genome. High-throughput sequencing (Illumina HiSeq) and Sanger sequencing of the total RNA extract from a cowpea plant collected in Teresina city, Brazil, revealed the genome sequence of the CPSMV-Ter1 isolate. RNA-1 and RNA-2 are, respectively, 5921 and 3465 nucleotides (nt) long without the poly(A) tail, and show 77.91% and 76.08% nt sequence identity with CPSMV-DG, considered the type isolate of the species. The open reading frames (ORFs) were determined and the cleavage sites of the polyproteins were predicted. Although the two isolates show a similar genomic organization, there was a low percentage of sequence identity between Ter1 and DG. Furthermore, pairwise comparisons of a partial RNA-1 fragment between CPSMV-Ter1 and 11 CPSMV isolates from Brazil indicated 94.6 to 94.8% nt and 98.9% to 99.4% aa sequence identities.

Assessment of selenium spatial distribution using µ-XFR in cowpea (Vigna unguiculata (L.) Walp.) plants: Integration of physiological and biochemical responses.

Low concentrations of selenium (Se) are beneficial for plant growth. Foliar Se application at high concentrations is toxic to plants due to the formation of reactive oxygen species (ROS). This study characterized Se toxicity symptoms using X-ray fluorescence (XRF) technique in response to foliar Se application in cowpea plants. Five Se concentrations (0, 10, 25, 50, 100 e 150 g ha-1) were sprayed on leaves as sodium selenate. The visual symptoms of Se toxicity in cowpea leaves were separated into two stages: I) necrotic points with an irregular distribution and internerval chlorosis at the leaf limb border (50-100 g ha-1); II) total chlorosis with the formation of dark brown necrotic lesions (150 g ha-1). Foliar Se application at 50 g ha-1 increased photosynthetic pigments and yield. Ultrastructural analyses showed that Se foliar application above 50 g ha-1 disarranged the upper epidermis of cowpea leaves. Furthermore, Se application above 100 g ha-1 significantly increased the hydrogen peroxide concentration and lipid peroxidation inducing necrotic leaf lesions. Mapping of the elements in leaves using the XRF revealed high Se intensity, specifically in leaf necrotic lesions accompanied by calcium (Ca) as a possible attenuating mechanism of plant stress. The distribution of Se intensities in the seeds was homogeneous, without specific accumulation sites. Phosphorus (P) and sulfur (S) were found primarily located in the embryonic region. Understanding the factors involved in Se accumulation and its interaction with Ca support new preventive measurement technologies to prevent Se toxicity in plants.

The resistance of the cowpea cv. BRS Xiquexique to infestation by cowpea weevil is related to the presence of toxic chitin-binding proteins.

The cowpea weevil (Callosobruchus maculatus) is the main pest that attacks cowpea (Vigna unguiculata) seeds during storage, causing nutritional and economic losses in the cowpea crop. Thus, studies aiming to identify resistant cowpea cultivars have been developed. Chitin-binding proteins (CBP), such vicilins and chitinases, have been detected in seeds and related with the toxicity to insects. In this work, we investigated the presence of chitin-binding proteins in the partially resistant cowpea cv. BRS Xiquexique and evaluated their toxicity towards cowpea weevil. The CBP fraction was isolated by chitin affinity chromatography. CBP fraction showed, through 15% SDS PAGE, protein bands with varying molecular masses, mainly below 55 kDa. Proteins present in CBP fraction were identified by Western blotting and mass spectrometry analysis, as vicilins and chitinases. CBP fraction, at 5%, was able to interfere with the development of cowpea weevil, decreasing larval mass and length. A CBV (chitin-binding vicilin) fraction isolated from CBP fraction was toxic, at 2.0%, to C. maculatus, decreasing larval mass and length in 64.3% and 33.23%, respectively. These results suggest that chitin binding proteins, such vicilins and chitinases, may be related to the resistance of cowpea cv. BRS Xiquexique to the infestation by C. maculatus.