Exploration of the pearl millet phospholipase gene family to identify potential candidates for grain quality traits.

BACKGROUND: Phospholipases constitute a diverse category of enzymes responsible for the breakdown of phospholipids. Their involvement in signal transduction with a pivotal role in plant development and stress responses is well documented. RESULTS: In the present investigation, a thorough genome-wide analysis revealed that the pearl millet genome contains at least 44 phospholipase genes distributed across its 7 chromosomes, with chromosome one harbouring the highest number of these genes. The synteny analysis suggested a close genetic relationship of pearl millet phospholipases with that of foxtail millet and sorghum. All identified genes were examined to unravel their gene structures, protein attributes, cis-regulatory elements, and expression patterns in two pearl millet genotypes contrasting for rancidity. All the phospholipases have a high alpha-helix content and distorted regions within the predicted secondary structures. Moreover, many of these enzymes possess binding sites for both metal and non-metal ligands. Additionally, the putative promoter regions associated with these genes exhibit multiple copies of cis-elements specifically responsive to biotic and abiotic stress factors and signaling molecules. The transcriptional profiling of 44 phospholipase genes in two genotypes contrasting for rancidity across six key tissues during pearl millet growth revealed a predominant expression in grains, followed by seed coat and endosperm. Specifically, the genes PgPLD-alpha1-1, PgPLD-alpha1-5, PgPLD-delta1-7a, PgPLA1-II-1a, and PgPLD-delta1-2a exhibited notable expression in grains of both the genotypes while showing negligible expression in the other five tissues. The sequence alignment of putative promoters revealed several variations including SNPs and InDels. These variations resulted in modifications to the corresponding cis-acting elements, forming distinct transcription factor binding sites suggesting the transcriptional-level regulation for these five genes in pearl millet. CONCLUSIONS: The current study utilized a genome-wide computational analysis to characterize the phospholipase gene family in pearl millet. A comprehensive expression profile of 44 phospholipases led to the identification of five grain-specific candidates. This underscores a potential role for at least these five genes in grain quality traits including the regulation of rancidity in pearl millet. Therefore, this study marks the first exploration highlighting the possible impact of phospholipases towards enhancing agronomic traits in pearl millet.

A Quantitative Theory for Genomic Offset Statistics.

Genomic offset statistics predict the maladaptation of populations to rapid habitat alteration based on association of genotypes with environmental variation. Despite substantial evidence for empirical validity, genomic offset statistics have well-identified limitations, and lack a theory that would facilitate interpretations of predicted values. Here, we clarified the theoretical relationships between genomic offset statistics and unobserved fitness traits controlled by environmentally selected loci and proposed a geometric measure to predict fitness after rapid change in local environment. The predictions of our theory were verified in computer simulations and in empirical data on African pearl millet (Cenchrus americanus) obtained from a common garden experiment. Our results proposed a unified perspective on genomic offset statistics and provided a theoretical foundation necessary when considering their potential application in conservation management in the face of environmental change.

Transcriptome analysis of Pennisetum americanum × Pennisetum purpureum and Pennisetum americanum leaves in response to high-phosphorus stress.

Excessive phosphorus (P) levels can disrupt nutrient balance in plants, adversely affecting growth. The molecular responses of Pennisetum species to high phosphorus stress remain poorly understood. This study examined two Pennisetum species, Pennisetum americanum × Pennisetum purpureum and Pennisetum americanum, under varying P concentrations (200, 600 and 1000 µmol·L- 1 KH2PO4) to elucidate transcriptomic alterations under high-P conditions. Our findings revealed that P. americanum exhibited stronger adaption to high-P stress compared to P. americanum× P. purpureum. Both species showed an increase in plant height and leaf P content under elevated P levels, with P. americanum demonstrating greater height and higher P content than P. americanum× P. purpureum. Transcriptomic analysis identified significant up- and down-regulation of key genes (e.g. SAUR, GH3, AHP, PIF4, PYL, GST, GPX, GSR, CAT, SOD1, CHS, ANR, P5CS and PsbO) involved in plant hormone signal transduction, glutathione metabolism, peroxisomes, flavonoid biosynthesis, amino acid biosynthesis and photosynthesis pathways. Compared with P. americanum× P. purpureum, P. americanum has more key genes in the KEGG pathway, and some genes have higher expression levels. These results contribute valuable insights into the molecular mechanisms governing high-P stress in Pennisetum species and offer implications for broader plant stress research.

Comprehensive genomic analysis of Bacillus subtilis and Bacillus paralicheniformis associated with the pearl millet panicle reveals their antimicrobial potential against important plant pathogens.

BACKGROUND: Plant microbiome confers versatile functional roles to enhance survival fitness as well as productivity. In the present study two pearl millet panicle microbiome member species Bacillus subtilis PBs 12 and Bacillus paralicheniformis PBl 36 found to have beneficial traits including plant growth promotion and broad-spectrum antifungal activity towards taxonomically diverse plant pathogens. Understanding the genomes will assist in devising a bioformulation for crop protection while exploiting their beneficial functional roles. RESULTS: Two potential firmicute species were isolated from pearl millet panicles. Morphological, biochemical, and molecular characterization revealed their identities as Bacillus subtilis PBs 12 and Bacillus paralicheniformis PBl 36. The seed priming assays revealed the ability of both species to enhance plant growth promotion and seedling vigour index. Invitro assays with PBs 12 and PBl 36 showed the antibiosis effect against taxonomically diverse plant pathogens (Magnaporthe grisea; Sclerotium rolfsii; Fusarium solani; Alternaria alternata; Ganoderma sp.) of crops and multipurpose tree species. The whole genome sequence analysis was performed to unveil the genetic potential of these bacteria for plant protection. The complete genomes of PBs 12 and PBl 36 consist of a single circular chromosome with a size of 4.02 and 4.33 Mb and 4,171 and 4,606 genes, with a G + C content of 43.68 and 45.83%, respectively. Comparative Average Nucleotide Identity (ANI) analysis revealed a close similarity of PBs 12 and PBl 36 with other beneficial strains of B. subtilis and B. paralicheniformis and found distant from B. altitudinis, B. amyloliquefaciens, and B. thuringiensis. Functional annotation revealed a majority of pathway classes of PBs 12 (30) and PBl 36 (29) involved in the biosynthesis of secondary metabolites, polyketides, and non-ribosomal peptides, followed by xenobiotic biodegradation and metabolism (21). Furthermore, 14 genomic regions of PBs 12 and 15 of PBl 36 associated with the synthesis of RiPP (Ribosomally synthesized and post-translationally modified peptides), terpenes, cyclic dipeptides (CDPs), type III polyketide synthases (T3PKSs), sactipeptides, lanthipeptides, siderophores, NRPS (Non-Ribosomal Peptide Synthetase), NRP-metallophone, etc. It was discovered that these areas contain between 25,458 and 33,000 secondary metabolite-coding MiBiG clusters which code for a wide range of products, such as antibiotics. The PCR-based screening for the presence of antimicrobial peptide (cyclic lipopeptide) genes in PBs 12 and 36 confirmed their broad-spectrum antifungal potential with the presence of spoVG, bacA, and srfAA AMP genes, which encode antimicrobial compounds such as subtilin, bacylisin, and surfactin. CONCLUSION: The combined in vitro studies and genome analysis highlighted the antifungal potential of pearl millet panicle-associated Bacillus subtilis PBs12 and Bacillus paralicheniformis PBl36. The genetic ability to synthesize several antimicrobial compounds indicated the industrial value of PBs 12 and PBl 36, which shed light on further studies to establish their action as a biostimulant for crop protection.

Omics-driven utilization of wild relatives for empowering pre-breeding in pearl millet.

MAIN CONCLUSION: Pearl millet wild relatives harbour novel alleles which could be utilized to broaden genetic base of cultivated species. Genomics-informed pre-breeding is needed to speed up introgression from wild to cultivated gene pool in pearl millet. Rising episodes of intense biotic and abiotic stresses challenge pearl millet production globally. Wild relatives provide a wide spectrum of novel alleles which could address challenges posed by climate change. Pre-breeding holds potential to introgress novel diversity in genetically narrow cultivated Pennisetum glaucum from diverse gene pool. Practical utilization of gene pool diversity remained elusive due to genetic intricacies. Harnessing promising traits from wild pennisetum is limited by lack of information on underlying candidate genes/QTLs. Next-Generation Omics provide vast scope to speed up pre-breeding in pearl millet. Genomic resources generated out of draft genome sequence and improved genome assemblies can be employed to utilize gene bank accessions effectively. The article highlights genetic richness in pearl millet and its utilization with a focus on harnessing next-generation Omics to empower pre-breeding.

Consensus genetic linkage map and QTL mapping allow to capture the genomic regions associated with agronomic traits in pearl millet.

MAIN CONCLUSION: A genetic linkage map representing the pearl millet genome was constructed with SNP markers. Major and stable QTL associated with flowering, number of productive tillers, ear head length, and test weight were mapped on chromosomes 1 and 3. Pearl millet (Pennisetum glaucum) is a major cereal and fodder crop in arid and semi-arid regions of Asia and Africa. Agronomic traits are important traits in pearl millet breeding and genetic and environmental factors highly influence them. In the present study, an F9 recombinant inbred line (RIL) population derived from a cross between PT6029 and PT6129 was evaluated for agronomic traits in three environments. Utilizing a genotyping by sequencing approach, a dense genetic map with 993 single nucleotide polymorphism markers covering a total genetic distance of 1035.4 cM was constructed. The average interval between the markers was 1.04 cM, and the seven chromosomes varied from 115.39 to 206.72 cM. Quantitative trait loci (QTL) mapping revealed 35 QTL for seven agronomic traits, and they were distributed on all pearl millet chromosomes. These QTL individually explained 11.35 to 26.71% of the phenotypic variation, with LOD values ranging from 2.74 to 5.80. Notably, four QTL (qDFF1.1, qNPT3.1, qEHL3.1, and qTW1.1) associated with days to fifty percent flowering, the number of productive tillers, ear head length, and test weight were found to be major and stable QTL located on chromosomes 1 and 3. Collectively, our results provide an important base for understanding the genetic architecture of agronomic traits in pearl millet, which is useful for accelerating the genetic gain toward crop improvement.

Genome-wide SNPs and candidate genes underlying the genetic variations for protein and amino acids in pearl millet (Pennisetum glaucum) germplasm.

MAIN CONCLUSION: A total of 544 significant marker-trait associations and 286 candidate genes associated with total protein and 18 amino acids were identified. Thirty-three candidate genes were found near the strong marker trait associations (- log10P ≥ 5.5). Pearl millet (Pennisetum glaucum) is largely grown as a subsistence crop in South Asia and sub-Saharan Africa. It serves as a major source of daily protein intake in these regions. Despite its importance, no systematic effort has been made to study the genetic variations of protein and amino acid content in pearl millet germplasm. The present study was undertaken to dissect the global genetic variations of total protein and 18 essential and non-essential amino acids in pearl millet, using a set of 435 K Single Nucleotide Polymorphisms (SNPs) and 161 genotypes of the Pearl Millet Inbred Germplasm Association Panel (PMiGAP). A total of 544 significant marker-trait associations (at P < 0.0001; - log10P ≥ 4) were detected and 23 strong marker-trait associations were identified using Bonferroni's correction method. Forty-eight pleiotropic loci were found in the genome for the studied traits. In total, 286 candidate genes associated with total protein and 18 amino acids were identified. Thirty-three candidate genes were found near strongly associated SNPs. The associated markers and the candidate genes provide an insight into the genetic architecture of the traits studied and are going to be useful in breeding improved pearl millet varieties in the future. Availabilities of improved pearl millet varieties possessing higher protein and amino acid compositions will help combat the rising malnutrition problem via diet.

Genome-wide characterization of the NBLRR gene family provides evolutionary and functional insights into blast resistance in pearl millet (Cenchrus americanus (L.) Morrone).

MAIN CONCLUSION: The investigation is the first report on genome-wide identification and characterization of NBLRR genes in pearl millet. We have shown the role of gene loss and purifying selection in the divergence of NBLRRs in Poaceae lineage and candidate CaNBLRR genes for resistance to Magnaporthe grisea infection. Plants have evolved multiple integral mechanisms to counteract the pathogens' infection, among which plant immunity through NBLRR (nucleotide-binding site, leucine-rich repeat) genes is at the forefront. The genome-wide mining in pearl millet (Cenchrus americanus (L.) Morrone) revealed 146 CaNBLRRs. The variation in the branch length of NBLRRs showed the dynamic nature of NBLRRs in response to evolving pathogen races. The orthology of NBLRRs showed a predominance of many-to-one orthologs, indicating the divergence of NBLRRs in the pearl millet lineage mainly through gene loss events followed by gene gain through single-copy duplications. Further, the purifying selection (Ka/Ks < 1) shaped the expansion of NBLRRs within the lineage of pear millet and other members of Poaceae. Presence of cis-acting elements, viz. TCA element, G-box, MYB, SARE, ABRE and conserved motifs annotated with P-loop, kinase 2, RNBS-A, RNBS-D, GLPL, MHD, Rx-CC and LRR suggests their putative role in disease resistance and stress regulation. The qRT-PCR analysis in pearl millet lines showing contrasting responses to Magnaporthe grisea infection identified CaNBLRR20, CaNBLRR33, CaNBLRR46 CaNBLRR51, CaNBLRR78 and CaNBLRR146 as putative candidates. Molecular docking showed the involvement of three and two amino acid residues of LRR domains forming hydrogen bonds (histidine, arginine and threonine) and salt bridges (arginine and lysine) with effectors. Whereas 14 and 20 amino acid residues of CaNBLRR78 and CaNBLRR20 showed hydrophobic interactions with 11 and 9 amino acid residues of effectors, Mg.00g064570.m01 and Mg.00g006570.m01, respectively. The present investigation gives a comprehensive overview of CaNBLRRs and paves the foundation for their utility in pearl millet resistance breeding through understanding of host-pathogen interactions.

Transcriptomic and physiological analysis provide new insight into seed shattering mechanism in Pennisetum alopecuroides 'Liqiu'.

KEY MESSAGE: Through the histological, physiological, and transcriptome-level identification of the abscission zone of Pennisetum alopecuroides 'Liqiu', we explored the structure and the genes related to seed shattering, ultimately revealing the regulatory network of seed shattering in P. alopecuroides. Pennisetum alopecuroides is one of the most representative ornamental grass species of Pennisetum genus. It has unique inflorescence, elegant appearance, and strong stress tolerance. However, the shattering of seeds not only reduces the ornamental effect, but also hinders the seed production. In order to understand the potential mechanisms of seed shattering in P. alopecuroides, we conducted morphological, histological, physiological, and transcriptomic analyses on P. alopecuroides cv. 'Liqiu'. According to histological findings, the seed shattering of 'Liqiu' was determined by the abscission zone at the base of the pedicel. Correlation analysis showed that seed shattering was significantly correlated with cellulase, lignin, auxin, gibberellin, cytokinin and jasmonic acid. Through a combination of histological and physiological analyses, we observed the accumulation of cellulase and lignin during 'Liqiu' seed abscission. We used PacBio full-length transcriptome sequencing (SMRT) combined with next-generation sequencing (NGS) transcriptome technology to improve the transcriptome data of 'Liqiu'. Transcriptomics further identified many differential genes involved in cellulase, lignin and plant hormone-related pathways. This study will provide new insights into the research on the shattering mechanism of P. alopecuroides.

Pearl millet a promising fodder crop for changing climate: a review.

The agricultural sector faces colossal challenges amid environmental changes and a burgeoning human population. In this context, crops must adapt to evolving climatic conditions while meeting increasing production demands. The dairy industry is anticipated to hold the highest value in the agriculture sector in future. The rise in the livestock population is expected to result in an increased demand for fodder feed. Consequently, it is crucial to seek alternative options, as crops demand fewer resources and are resilient to climate change. Pearl millet offers an apposite key to these bottlenecks, as it is a promising climate resilience crop with significantly low energy, water and carbon footprints compared to other crops. Numerous studies have explored its potential as a fodder crop, revealing promising performance. Despite its capabilities, pearl millet has often been overlooked. To date, few efforts have been made to document molecular aspects of fodder-related traits. However, several QTLs and candidate genes related to forage quality have been identified in other fodder crops, which can be harnessed to enhance the forage quality of pearl millet. Lately, excellent genomic resources have been developed in pearl millet allowing deployment of cutting-edge genomics-assisted breeding for achieving a higher rate of genetic gains. This review would facilitate a deeper understanding of various aspects of fodder pearl millet in retrospect along with the future challenges and their solution. This knowledge may pave the way for designing efficient breeding strategies in pearl millet thereby supporting sustainable agriculture and livestock production in a changing world.

DNAJ protein gene expansion mechanism in Panicoideae and PgDNAJ functional identification in pearl millet.

KEY MESSAGE: Analyze the evolutionary pattern of DNAJ protein genes in the Panicoideae, including pearl millet, to identify and characterize the biological function of PgDNAJ genes in pearl millet. Global warming has become a major factor threatening food security and human development. It is urgent to analyze the heat-tolerant mechanism of plants and cultivate crops that are adapted to high temperature conditions. The Panicoideae are the second largest subfamily of the Poaceae, widely distributed in warm temperate and tropical regions. Many of these species have been reported to have strong adaptability to high temperature stress, such as pearl millet, foxtail millet and sorghum. The evolutionary differences in DNAJ protein genes among 12 Panicoideae species and 10 other species were identified and analyzed. Among them, 79% of Panicoideae DNAJ protein genes were associated with retrotransposon insertion. Analysis of the DNAJ protein pan-gene family in six pearl millet accessions revealed that the non-core genes contained significantly more TEs than the core genes. By identifying and analyzing the distribution and types of TEs near the DNAJ protein genes, it was found that the insertion of Copia and Gypsy retrotransposons provided the source of expansion for the DNAJ protein genes in the Panicoideae. Based on the analysis of the evolutionary pattern of DNAJ protein genes in Panicoideae, the PgDNAJ was obtained from pearl millet through identification. PgDNAJ reduces the accumulation of reactive oxygen species caused by high temperature by activating ascorbate peroxidase (APX), thereby improving the heat resistance of plants. In summary, these data provide new ideas for mining potential heat-tolerant genes in Panicoideae, and help to improve the heat tolerance of other crops.

Introgression of Δ1-pyrroline-5-carboxylate synthetase (PgP5CS) confers enhanced resistance to abiotic stresses in transgenic tobacco.

Δ1-pyrroline-5-carboxylate synthetase (P5CS) is one of the key regulatory enzymes involved in the proline biosynthetic pathway. Proline acts as an osmoprotectant, molecular chaperone, antioxidant, and regulator of redox homeostasis. The accumulation of proline during stress is believed to confer tolerance in plants. In this study, we cloned the complete CDS of the P5CS from pearl millet (Pennisetum glaucum (L.) R.Br. and transformed into tobacco. Three transgenic tobacco plants with single-copy insertion were analyzed for drought and heat stress tolerance. No difference was observed between transgenic and wild-type (WT) plants when both were grown in normal conditions. However, under heat and drought, transgenic plants have been found to have higher chlorophyll, relative water, and proline content, and lower malondialdehyde (MDA) levels than WT plants. The photosynthetic parameters (stomatal conductance, intracellular CO2 concentration, and transpiration rate) were also observed to be high in transgenic plants under abiotic stress conditions. qRT-PCR analysis revealed that the expression of the transgene in drought and heat conditions was 2-10 and 2-7.5 fold higher than in normal conditions, respectively. Surprisingly, only P5CS was increased under heat stress conditions, indicating the possibility of feedback inhibition. Our results demonstrate the positive role of PgP5CS in enhancing abiotic stress tolerance in tobacco, suggesting its possible use to increase abiotic stress-tolerance in crops for sustained yield under adverse climatic conditions.

Evaluating Plant Growth-Promoting Rhizobacteria to Improve the Productivity of Forage Pearl Millet.

India's livestock industry is grappling with a shortage of green fodder, necessitating concerted efforts to boost organized production and ensure a sufficient supply of high-quality forages, crucial for formulating nutritionally balanced, cost-effective, and rumen-healthy animal diets. Hence, this study was conducted to assess the plant growth-promoting characteristics of liquid microbial inoculants and their impact on the yield of forage pearl millet. The bacterial cultures utilized included Sphingobacterium sp., Stenotrophomonas maltophilia, and an isolate from vegetable cowpea, subsequently identified as Burkholderia seminalis. These cultures were initially characterized for their plant growth-promoting traits at different temperature and physiological conditions. All the bacterial cultures were found promising for PGPR traits over varied temperature conditions and the optimum activity was recorded at 40 °C, with tolerance to saline and drought stresses as well as wide pH and temperature ranges. A field experiment was conducted during kharif 2020 at Punjab Agricultural University, Ludhiana and Punjab Agricultural University, Regional Research Station, Bathinda, involving combinations of liquid microbial inoculants along with 100% Recommended Dose of Fertilizer (RDF). It was observed that the treatment including B. seminalis + S. maltophilia along with RDF yielded the highest green fodder and dry matter yield, In conclusion, it is evident that the utilization of these liquid microbial inoculants holds significant potential for playing a pivotal role in the integrated nutrient management of forage pearl millet, thereby contributing to heightened productivity and sustained soil health.

Differential subgenome expression underlies biomass accumulation in allotetraploid Pennisetum giganteum.

BACKGROUND: Pennisetum giganteum (AABB, 2n = 4x = 28) is a C4 plant in the genus Pennisetum with origin in Africa but currently also grown in Asia and America. It is a crucial forage and potential energy grass with significant advantages in yield, stress resistance, and environmental adaptation. However, the mechanisms underlying these advantageous traits remain largely unexplored. Here, we present a high-quality genome assembly of the allotetraploid P. giganteum aiming at providing insights into biomass accumulation. RESULTS: Our assembly has a genome size 2.03 Gb and contig N50 of 88.47 Mb that was further divided into A and B subgenomes. Genome evolution analysis revealed the evolutionary relationships across the Panicoideae subfamily lineages and identified numerous genome rearrangements that had occurred in P. giganteum. Comparative genomic analysis showed functional differentiation between the subgenomes. Transcriptome analysis found no subgenome dominance at the overall gene expression level; however, differentially expressed homoeologous genes and homoeolog-specific expressed genes between the two subgenomes were identified, suggesting that complementary effects between the A and B subgenomes contributed to biomass accumulation of P. giganteum. Besides, C4 photosynthesis-related genes were significantly expanded in P. giganteum and their sequences and expression patterns were highly conserved between the two subgenomes, implying that both subgenomes contributed greatly and almost equally to the highly efficient C4 photosynthesis in P. giganteum. We also identified key candidate genes in the C4 photosynthesis pathway that showed sustained high expression across all developmental stages of P. giganteum. CONCLUSIONS: Our study provides important genomic resources for elucidating the genetic basis of advantageous traits in polyploid species, and facilitates further functional genomics research and genetic improvement of P. giganteum.

Phytostabilization of fly ash from a coalmine in Botswana and biovalorisation of the recovered Napier grass (Pennisetum purpureum Schumach.).

The disposal of fly ash (FA) from coal power plants polluting the air, soil, and groundwater is a major environmental concern. Phytoremediation to rehabilitate fly ash dumpsites is a promising alternative but has practical concerns about the disposal of harvested biomass. This study investigated the effect of supplementing fly ash with fresh sewage sludge (FSS), aged sewage sludge, food waste, and compost (COM) to enhance the phytoremediation potential of Napier grass and its subsequent utilization for ethanol production. The highest removal of Mn (1196.12 g ha-1) and Ni (128.06 g ha-1) from FA could be obtained when Napier is grown in the presence of FSS and inorganic fertilizer (NPK). In addition, the highest bioethanol yield (19.31 g L-1) was obtained from Napier grown in fly ash with COM + NPK, thus providing additional economic benefits aside from the remediation process. Given the significant levels of heavy metals present in the pulp and bio-slurry after ethanol production, further research is required in this area to determine the best ways to utilize this waste such as converting it into biochar.

Using energy crops as a phytoremediation agent for fly ash dumpsites has the potential to remediate heavy metal contamination and provide additional economic benefits. Napier grass was able to tolerate high concentrations of heavy metals and yield high biomass in fly ash in the presence of organic amendments. The harvested biomass was successfully converted into substrate for bioethanol production using heavy metal-tolerant yeast. This is the first report on the production of ethanol from the phytoremediation biomass of Napier grass.

Rhizosphere microbiome of plants used in phytoremediation of mine tailing dams.

Rhizospheric microbial communities improve the effectiveness of hyperaccumulators in the phytoremediation of heavy metals. However, limited access to tailing dams and inadequate assessment of plants' phytoremediation potential limit the characterization of native accumulators, hindering the effectiveness of local remediation efforts. This study evaluates the heavy metal sequestration potentials of Pennisetum purpureum, Leucaena leucocephala, and Pteris vittata and their associated rhizospheric microbial communities at the Marlu and Pompora tailing dams in Ghana. The results indicate shoot hyperaccumulation of Cd (334.5 ± 6.3 mg/kg) and Fe (10,647.0 ± 12.6 mg/kg) in P. purpureum and L. leucocephala, respectively. Analysis of rhizospheric bacterial communities revealed the impact of heavy metal contamination on bacterial community composition, associating Fe and Cd hyperaccumulation with Bacillus, Arthrobacter, and Sphingomonas species. This study reports the hyperaccumulation potentials of L. leucocephala and P. purpureum enhanced by associated rhizosphere bacterial communities, suggesting their potential application as an environmentally friendly remediation process of heavy metals contaminated lands.

The novelty of this study is the report of the heavy metal accumulation potentials of the fast-growing herbaceous plants Leucaena leucocephala and Pennisetum purpureum at abandoned gold mine tailing dams in Ghana. Substantial amounts of Cd (334.5 mg/kg) and Fe (10,647.0 mg/kg) were accumulated in P. purpureum and L. leucocephala shoots, indicating their hyperaccumulation potentials. The concentration of heavy metal levels in the rhizosphere influenced the bacterial community structure, with the abundance of Bacillus, Arthrobacter, and Sphingomonas linked to hyperaccumulation. The outcome of this study supports the utilization of L. leucocephala and P. purpureum in the phytoremediation of lands contaminated with heavy metals.

Genome-Wide Identification and Transcriptional Analysis of AP2/ERF Gene Family in Pearl Millet (Pennisetum glaucum).

The apetala2/ethylene response factor (AP2/ERF) gene family plays a crucial role in regulating plant growth and development and responding to different abiotic stresses (e.g., drought, heat, cold, and salinity). However, the knowledge of the ERF family in pearl millet remains limited. Here, a total of 167 high-confidence PgERF genes are identified and divided into five subgroups based on gene-conserved structure and phylogenetic analysis. Forty-one pairs of segmental duplication are found using collinear analysis. Nucleotide substitution analysis reveals these duplicated pairs are under positive purification, indicating they are actively responding to natural selection. Comprehensive transcriptomic analysis reveals that PgERF genesare preferentially expressed in the imbibed seeds and stem (tilling stage) and respond to heat, drought, and salt stress. Prediction of the cis-regulatory element by the PlantCARE program indicates that PgERF genes are involved in responses to environmental stimuli. Using reverse transcription quantitative real-time PCR (RT-qPCR), expression profiles of eleven selected PgERF genes are monitored in various tissues and during different abiotic stresses. Transcript levels of each PgERF gene exhibit significant changes during stress treatments. Notably, the PgERF7 gene is the only candidate that can be induced by all adverse conditions. Furthermore, four PgERF genes (i.e., PgERF22, PgERF37, PgERF88, and PgERF155) are shown to be involved in the ABA-dependent signaling pathway. These results provide useful bioinformatic and transcriptional information for understanding the roles of the pearl millet ERF gene family in adaptation to climate change.

The dominant-substrate driven the enhanced performance in co-digestion of Pennisetum hybrid and livestock waste.

Co-digestion has been considered a promising method to improve methane yield. The effect of the proportion of dominant substrate on the performance and microbial community of anaerobic digestion of Pennisetum hybrid (PH) and livestock waste (LW) was investigated. An obvious synergistic effect was obtained with an increase of 15.20%-17.45% in specific methane yield compared to the predicted value. Meanwhile, the dominant substrate influenced the relational model between methane yield enhancement rate and mixture ratio. For the LW-dominant systems, a parabolic model between enhancement rate and mixture ratio was observed with a highest value of 392.16 mL/g VS achieved at a PH:LW ratio of 2:8. While a linear pattern appeared for PH-dominant systems with the highest methane yield of 307.59 mL/g VS. Co-digestion selectively enriched the relative abundance of Clostridium_sensu_stricto_1, Terrisporobacter, Syntrophomonas, Methanosarcina and Methanobacterium, which boosted the performance of hydrolysis, acidogenesis, acetogenesis and methanogenesis processes.

Evaluating the 3D printability of pearl millet flour with banana pulp blends.

BACKGROUND: Three-dimensional (3D) food printing is a promising method for developing nutritious snack foods with complex and customized structures. In this study, to develop a pearl millet-based snack formulation, the printability of pearl millet flour (PMF) was assessed, without and with the addition of banana pulp (BP), a natural taste and flavor enhancer, at five different levels (PMF:BP of 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100). RESULTS: The water activity significantly decreased with increases in the proportion of BP; higher water activity was exhibited at 100:0 (0.99). The BP proportion influences all the color values (redness: 2-11; yellowness: 17-31.87; total color difference: 2-17). All formulations exhibited shear-thinning behavior (n = 0.02-0.49) and higher hardness (0.2-0.4 N), but not all were printable. A significant decrease in adhesiveness (-0.2 to -0.03 N s) and higher storage modulus (2000-6000 Pa) occurred with an increased proportion of BP. Findings from detailed rheological behavior assessment (static, dynamic and three-interval thixotropy tests) better correlated with trends observed during 3D extrusion printing. The highest yield stress was attained (80 Pa) in the 100:0 formulation. From the thixotropy test, more deformation (>80%) and recovery (>100%) were attained by three of the formulations (100:0, 80:20, 60:40). Overall, the best constructs were obtained (based on the visual sensory characteristics) for the 60:40 formulation printed at 600 mm min-1 printing speed and 240 rpm extrusion motor speed through a 1.22 mm nozzle. CONCLUSION: The findings of this work will provide valuable insights into the development of novel millet-based 3D printed foods. © 2024 Society of Chemical Industry.

Impacts of soil type and drought stress on growth and cesium accumulation in Napier grass.

In our previous study, the decontamination efficiency of cesium-137 (137Cs) by Napier grass (Pennisetum purpureum Schum.) in the field was shown to be variable and often influenced by natural environmental factors. To elucidate the factors influencing this variable 137Cs-decontamination efficiency, we investigated the influences of soil type and drought stress on Cs accumulation using cesium-133 (133Cs) in Napier grass grown in plastic containers. The experiment was performed using two soil types (Soil A and B) and three different soil moisture conditions: well-watered control (CL), slight drought stress (SD), and moderate drought stress (MD). Overall, our results indicate that soil type and drought have a significant impact on plant growth and 133Cs accumulation in Napier grass. Plant height (PH), tiller number (TN), leaf width (Wleaf), and dry matter weight of aboveground parts (DWabove) and root parts (DWroot) in Soil B were greater than those in Soil A. Drought stress negatively affected chlorophyll fluorescence parameters (maximal quantum efficiency of photosystem (PS) II photochemistry and potential activity of PS II), PH, TN, Wleaf, DWabove, DWroot, and total 133Cs content (TCs), but it had a positive effect on 133Cs concentration. The 133Cs concentration in the aboveground parts (Csabove) was increased by MD approximately 1.62-fold in Soil A and 1.11-fold in Soil B compared to each CL counterpart. The TCs in the aboveground parts (TCsabove) decreased due to drought by approximately 19.9%-39.0% in Soil A and 49.9%-62.7% in Soil B; however, there was no significant effect on TCsabove due to soil type. The results of this study indicate that soil moisture is a key factor in maintaining Napier grass 137Cs-decontamination efficiency.