Comparative analysis of lipid and flavonoid biosynthesis between Pongamia and soybean seeds: genomic, transcriptional, and metabolic perspectives.

BACKGROUND: Soybean (Glycine max) is a vital oil-producing crop. Augmenting oleic acid (OA) levels in soybean oil enhances its oxidative stability and health benefits, representing a key objective in soybean breeding. Pongamia (Pongamia pinnata), known for its abundant oil, OA, and flavonoid in the seeds, holds promise as a biofuel and medicinal plant. A comparative analysis of the lipid and flavonoid biosynthesis pathways in Pongamia and soybean seeds would facilitate the assessment of the potential value of Pongamia seeds and advance the genetic improvements of seed traits in both species. RESULTS: The study employed multi-omics analysis to systematically compare differences in metabolite accumulation and associated biosynthetic genes between Pongamia seeds and soybean seeds at the transcriptional, metabolic, and genomic levels. The results revealed that OA is the predominant free fatty acid in Pongamia seeds, being 8.3 times more abundant than in soybean seeds. Lipidomics unveiled a notably higher accumulation of triacylglycerols (TAGs) in Pongamia seeds compared to soybean seeds, with 23 TAG species containing OA. Subsequently, we identified orthologous groups (OGs) involved in lipid biosynthesis across 25 gene families in the genomes of Pongamia and soybean, and compared the expression levels of these OGs in the seeds of the two species. Among the OGs with expression levels in Pongamia seeds more than twice as high as in soybean seeds, we identified one fatty acyl-ACP thioesterase A (FATA) and two stearoyl-ACP desaturases (SADs), responsible for OA biosynthesis, along with two phospholipid:diacylglycerol acyltransferases (PDATs) and three acyl-CoA:diacylglycerol acyltransferases (DGATs), responsible for TAG biosynthesis. Furthermore, we observed a significantly higher content of the flavonoid formononetin in Pongamia seeds compared to soybean seeds, by over 2000-fold. This difference may be attributed to the tandem duplication expansions of 2,7,4'-trihydroxyisoflavanone 4'-O-methyltransferases (HI4'OMTs) in the Pongamia genome, which are responsible for the final step of formononetin biosynthesis, combined with their high expression levels in Pongamia seeds. CONCLUSIONS: This study extends beyond observations made in single-species research by offering novel insights into the molecular basis of differences in lipid and flavonoid biosynthetic pathways between Pongamia and soybean, from a cross-species comparative perspective.

Telomere-to-telomere genome of the allotetraploid legume Sesbania cannabina reveals transposon-driven subgenome divergence and mechanisms of alkaline stress tolerance.

Alkaline soils pose an increasing problem for agriculture worldwide, but using stress-tolerant plants as green manure can improve marginal land. Here, we show that the legume Sesbania cannabina is very tolerant to alkaline conditions and, when used as a green manure, substantially improves alkaline soil. To understand genome evolution and the mechanisms of stress tolerance in this allotetraploid legume, we generated the first telomere-to-telomere genome assembly of S. cannabina spanning ∼2,087 Mb. The assembly included all centromeric regions, which contain centromeric satellite repeats, and complete chromosome ends with telomeric characteristics. Further genome analysis distinguished A and B subgenomes, which diverged approximately 7.9 million years ago. Comparative genomic analysis revealed that the chromosome homoeologs underwent large-scale inversion events (>10 Mb) and a significant, transposon-driven size expansion of the chromosome 5A homoeolog. We further identified four specific alkali-induced phosphate transporter genes in S. cannabina; these may function in alkali tolerance by relieving the deficiency in available phosphorus in alkaline soil. Our work highlights the significance of S. cannabina as a green tool to improve marginal lands and sheds light on subgenome evolution and adaptation to alkaline soils.

Multi-omics analysis reveals the roles of purple acid phosphatases in organic phosphorus utilization by the tropical legume Stylosanthes guianensis.

Stylo (Stylosanthes guianensis) is a tropical legume known for its exceptional tolerance to low phosphate (Pi), a trait believed to be linked to its high acid phosphatase (APase) activity. Previous studies have observed genotypic variations in APase activity in stylo; however, the gene encoding the crucial APase responsible for this variation remains unidentified. In this study, transcriptomic and proteomic analyses were employed to identify eight Pi starvation-inducible (PSI) APases belonging to the purple APase (PAP) family in the roots of stylo and seven in the leaves. Among these PSI-PAPs, SgPAP7 exhibited a significantly positive correlation in its expression levels with the activities of both internal APase and root-associated APase across 20 stylo genotypes under low-Pi conditions. Furthermore, the recombinant SgPAP7 displayed high catalytic activity toward adenosine 5'-diphosphate (ADP) and phosphoenolpyruvate (PEP) in vitro. Overexpression (OE) of SgPAP7 in Arabidopsis facilitated exogenous organic phosphorus utilization. Moreover, SgPAP7 OE lines showed lower shoot ADP and PEP levels than the wild type, implying that SgPAP7 is involved in the catabolism and recycling of endogenous ADP and PEP, which could be beneficial for plant growth in low-Pi soils. In conclusion, SgPAP7 is a key gene with a major role in stylo adaptation to low-Pi conditions by facilitating the utilization of both exogenous and endogenous organic phosphorus sources. It may also function as a PEP phosphatase involved in a glycolytic bypass pathway that minimizes the need for adenylates and Pi. Thus, SgPAP7 could be a promising target for improving tolerance of crops to low-Pi availability.

Multi-Omics Analysis Reveals Mechanisms of Strong Phosphorus Adaptation in Tea Plant Roots.

Low phosphorus (P) is a major limiting factor for plant growth in acid soils, which are preferred by tea plants. This study aims to investigate the unique mechanisms of tea plant roots adaptation to low-P conditions. Tea plant roots were harvested for multi-omics analysis after being treated with 0 µmol·L-1 P (0P) and 250 µmol·L-1 P (250P) for 30 days. Under 250P conditions, root elongation was significantly inhibited, and the density of lateral roots was dramatically increased. This suggests that 250P may inhibit the elongation of tea plant roots. Moreover, the P concentration in roots was about 4.58 times higher than that under 0P, indicating that 250P may cause P toxicity in tea plant roots. Contrary to common plants, the expression of CsPT1/2 in tea plant roots was significantly increased by four times at 250P, which indicated that tea plant roots suffering from P toxicity might be due to the excessive expression of phosphate uptake-responsible genes under 250P conditions. Additionally, 94.80% of P-containing metabolites accumulated due to 250P stimulation, most of which were energy-associated metabolites, including lipids, nucleotides, and sugars. Especially the ratio of AMP/ATP and the expression of energy sensor CsSnRKs were inhibited by P application. Therefore, under 250P conditions, P over-accumulation due to the excessive expression of CsPT1/2 may inhibit energy metabolism and thus the growth of tea plant roots.

Facile production of cellulose nanofibers from raw elephant grass by an aluminum chloride-enhanced acidic deep eutectic solvent.

To develop a greener and more efficient method for producing cellulose nanofibers (CNFs) from raw plants, an AlCl3-enhanced ternary deep eutectic solvent, DES2 (consisting of choline chloride, citric acid, and AlCl3·6H2O in a molar ratio of 1:0.4:0.08), was synthesized. Raw elephant grass (EG) was pretreated with DES2, followed by sodium chlorite (NaClO2) bleaching and ultrasonic disruption to extract high-performance CNFs. The DES2 and NaClO2 treatments effectively removed hemicellulose and lignin, achieving removal rates of 99.23 % and 99.62 %, respectively, while maintaining a cellulose content of 78.3 %. DES2 demonstrated easy recyclability and maintained excellent biomass pretreatment performance even after multiple cycles. Following a brief 30-min intermittent ultrasound treatment, the resulting CNFs demonstrated superior crystallinity, increased carboxyl content, and a narrower width distribution compared to CNFs obtained from AlCl3-free DES1. Optimized conditions at 110 °C yielded CNFs with 85.3 % crystallinity, 0.64 mmol/g carboxyl content, 5.15 nm width distribution, and excellent dispersion in water for at least six months. Additionally, CNFs enhanced the tensile strength of chia seed mucilage (CM) composite films, showing a significant improvement to 26.6 MPa, representing a 231.3 % increase over the control film. This study offers a promising approach for efficiently producing CNFs from raw plants.

Analysis of seed production and seed shattering in a new artificial grassland forage: pigeon pea.

Pigeon pea is a perennial leguminous plant that is widely cultivated as a forage and pharmaceutical plant in subtropical and tropical areas, especially in artificial grasslands. Higher seed shattering is one of the most important factors in potentially increasing the seed yield of pigeon pea. Advance technology is necessary to increase the seed yield of pigeon pea. Through 2 consecutive years of field observations, we found that fertile tiller number was the key component of the seed yield of pigeon pea due to the direct effect of fertile tiller number per plant (0.364) on pigeon pea seed yield was the highest. Multiplex morphology, histology, and cytological and hydrolytic enzyme activity analysis showed that shatter-susceptible and shatter-resistant pigeon peas possessed an abscission layer at the same time (10 DAF); however, abscission layer cells dissolved earlier in shattering-susceptible pigeon pea (15 DAF), which led to the tearing of the abscission layer. The number of vascular bundle cells and vascular bundle area were the most significant negative factors (p< 0.01) affecting seed shattering. Cellulase and polygalacturonase were involved in the dehiscence process. In addition, we inferred that larger vascular bundle tissues and cells in the ventral suture of seed pods could effectively resist the dehiscence pressure of the abscission layer. This study provides foundation for further molecular studies to increase the seed yield of pigeon pea.

Multi-omics-based identification of purple acid phosphatases and metabolites involved in phosphorus recycling in stylo root exudates.

Stylo (Stylosanthes guianensis) is a tropical forage and cover crop that possesses low phosphate (Pi) tolerance traits. However, the mechanisms underlying its tolerance to low-Pi stress, particularly the role of root exudates, remain unclear. This study employed an integrated approach using physiological, biochemical, multi-omics, and gene function analyses to investigate the role of stylo root exudates in response to low-Pi stress. Widely targeted metabolomic analysis revealed that eight organic acids and one amino acid (L-cysteine) were significantly increased in the root exudates of Pi-deficient seedlings, among which tartaric acid and L-cysteine had strong abilities to dissolve insoluble-P. Furthermore, flavonoid-targeted metabolomic analysis identified 18 flavonoids that were significantly increased in root exudates under low-Pi conditions, mainly belonging to the isoflavonoid and flavanone subclasses. Additionally, transcriptomic analysis revealed that 15 genes encoding purple acid phosphatases (PAPs) had upregulated expression in roots under low-Pi conditions. Among them, SgPAP10 was characterized as a root-secreted phosphatase, and overexpression of SgPAP10 enhanced organic-P utilization by transgenic Arabidopsis. Overall, these findings provide detailed information regarding the importance of stylo root exudates in adaptation to low-Pi stress, highlighting the plant's ability to release Pi from organic-P and insoluble-P sources through root-secreted organic acids, amino acids, flavonoids, and PAPs.

Association Between Serum Copper Levels and Urinary Incontinence in Adult Men.

Urinary incontinence (UI) is a major health burden to aging patients. The function of the trace element copper in male UI is unclear. To elaborate on the impact of serum copper levels on UI, we investigated the association between serum copper levels and UI using data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional survey of male participants aged 20 years old and older in the United States from 2011 to 2016. We performed weighted multivariable logistic and linear regression models to evaluate the association between serum copper levels and UI. Compared with serum copper levels in quartile 1 (Q1), serum copper levels in Q2 and Q3 were associated with stress urinary incontinence (SUI) after adjusting for all potential confounders (Q2, odds ratio [OR] = 0.292, 95% confidence interval [CI] = 0.093-0.920, P = 0.047; Q3, OR = 0.326, 95% CI = 0.113-0.937, P = 0.049). No significance was found between serum copper levels and other types of UI. Our findings revealed that the serum copper levels were inversely related to SUI in adult males. Race and education level might modulate this relationship. Further studies are warranted for validation.

Intercropping of Stylosanthes green manure could improve the organic nitrogen fractions in a coconut plantation with acid soil.

Intercropping green manure (GM) may be a good solution to the problems of acid soil in tropical plantations. Soil organic nitrogen (No) may change due to the application of GM. A three-year field experiment was conducted to determine the effect of different utilization patterns of Stylosanthes guianensis GM on soil No fractions in a coconut plantation. Three treatments were set: no GM intercropping (CK), intercropping and mulching utilization pattern (MUP), and intercropping and green manuring utilization pattern (GMUP). The content dynamics of soil total N (TN) and soil No fractions including of non-hydrolysable N (NHNo) and hydrolyzable N (HN) in the cultivated soil layer was examined. The results showed that after three years of intercropping, the TN content of the MUP and GMUP treatment was 29.4% and 58.1% respectively higher (P < 0.05) than those of the initial soil, and the No fractions content of GMUP and MUP treatment was 15.1%-60.0% and 32.7%-111.0% higher (P < 0.05) than those of the initial soil. The further results indicated that after three years of intercropping, compared with CK, GMUP and MUP could increase the content of TN by 32.6% and 61.7% respectively, and No fractions content was also increased by 15.2%-67.3% and 32.3%-120.3%% respectively (P < 0.05). The No fractions content of GMUP treatment was 10.3%-36.0% higher than those of MUP treatment (P < 0.05). These results indicated that intercropping Stylosanthes guianensis GM could significantly increase the soil N including of the TN an No fractions content, and the GMUP was more effective than MUP, therefore, GMUP is a better GM utilization pattern to improve the soil fertility and should be popularized in the tropical fruit plantation.

Genome-Wide Mining of the Tandem Duplicated Type III Polyketide Synthases and Their Expression, Structure Analysis of Senna tora.

Senna tora is one of the homologous crops used as a medicinal food containing an abundance of anthraquinones. Type III polyketide synthases (PKSs) are key enzymes that catalyze polyketide formation; in particular, the chalcone synthase-like (CHS-L) genes are involved in anthraquinone production. Tandem duplication is a fundamental mechanism for gene family expansion. However, the analysis of the tandem duplicated genes (TDGs) and the identification and characterization of PKSs have not been reported for S. tora. Herein, we identified 3087 TDGs in the S. tora genome; the synonymous substitution rates (Ks) analysis indicated that the TDGs had recently undergone duplication. The Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the type III PKSs were the most enriched TDGs involved in the biosynthesis of the secondary metabolite pathways, as evidenced by 14 tandem duplicated CHS-L genes. Subsequently, we identified 30 type III PKSs with complete sequences in the S. tora genome. Based on the phylogenetic analysis, the type III PKSs were classified into three groups. The protein conserved motifs and key active residues showed similar patterns in the same group. The transcriptome analysis showed that the chalcone synthase (CHS) genes were more highly expressed in the leaves than in the seeds in S. tora. The transcriptome and qRT-PCR analysis showed that the CHS-L genes had a higher expression in the seeds than in other tissues, particularly seven tandem duplicated CHS-L2/3/5/6/9/10/13 genes. The key active-site residues and three-dimensional models of the CHS-L2/3/5/6/9/10/13 proteins showed slight variation. These results indicated that the rich anthraquinones in S. tora seeds might be ascribed to the PKSs' expansion from tandem duplication, and the seven key CHS-L2/3/5/6/9/10/13 genes provide candidate genes for further research. Our study provides an important basis for further research on the regulation of anthraquinones' biosynthesis in S. tora.

Improving phosphorus acquisition efficiency through modification of root growth responses to phosphate starvation in legumes.

Phosphorus (P) is one of the essential macronutrients for plant growth and development, and it is an integral part of the major organic components, including nucleic acids, proteins and phospholipids. Although total P is abundant in most soils, a large amount of P is not easily absorbed by plants. Inorganic phosphate (Pi) is the plant-available P, which is generally immobile and of low availability in soils. Hence, Pi starvation is a major constraint limiting plant growth and productivity. Enhancing plant P efficiency can be achieved by improving P acquisition efficiency (PAE) through modification of morpho-physiological and biochemical alteration in root traits that enable greater acquisition of external Pi from soils. Major advances have been made to dissect the mechanisms underlying plant adaptation to P deficiency, especially for legumes, which are considered important dietary sources for humans and livestock. This review aims to describe how legume root growth responds to Pi starvation, such as changes in the growth of primary root, lateral roots, root hairs and cluster roots. In particular, it summarizes the various strategies of legumes to confront P deficiency by regulating root traits that contribute towards improving PAE. Within these complex responses, a large number of Pi starvation-induced (PSI) genes and regulators involved in the developmental and biochemical alteration of root traits are highlighted. The involvement of key functional genes and regulators in remodeling root traits provides new opportunities for developing legume varieties with maximum PAE needed for regenerative agriculture.

Development of transgenic composite Stylosanthes plants to study root growth regulated by a ß-expansin gene, SgEXPB1, under phosphorus deficiency.

KEY MESSAGE: A highly efficient transformation procedure to generate transgenic Stylosanthes roots was established. SgEXPB1 is involved in Stylosanthes root growth under phosphorus deficiency. Stylo (Stylosanthes spp.) is an important forage legume widely applied in agricultural systems in the tropics. Due to the recalcitrance of stylo genetic transformation, functional characterization of candidate genes involved in stylo root growth is limited. This study established an efficient procedure for Agrobacterium rhizogenes-mediated transformation for generating transgenic composite plants of S. guianensis cultivar 'Reyan No. 5'. Results showed that composite stylo plants with transgenic hairy roots were efficiently generated by A. rhizogenes strains K599 and Arqual, infecting the residual hypocotyl at 1.0 cm of length below the cotyledon leaves of 9-d-old seedlings, leading to a high transformation efficiency of > 95% based on histochemical ß-glucuronidase (GUS) staining. Notably, 100% of GUS staining-positive hairy roots can be achieved per composite stylo plant. Subsequently, SgEXPB1, a ß-expansin gene up-regulated by phosphorus (P) deficiency in stylo roots, was successfully overexpressed in hairy roots. Analysis of hairy roots showed that root growth and P concentration in the transgenic composite plants were increased by SgEXPB1 overexpression under low-P treatment. Taken together, a highly efficient A. rhizogenes-mediated transformation procedure for generating composite stylo plants was established to study the function of SgEXPB1, revealing that this gene is involved in stylo root growth during P deficiency.

Characterization of phosphate transporter genes and the function of SgPT1 involved in phosphate uptake in Stylosanthes guianensis.

Phosphorus (P) is one of the principal macronutrients for plant growth and productivity. Although the phosphate (Pi) transporter (PT) of the PHT1 family has been functionally characterized as participating in Pi uptake and transport in plants, information about PT genes in stylo (Stylosanthes guianensis), an important tropical forage legume that exhibits good adaptability to low-P acid soils, is limited. In this study, stylo root growth was found to be stimulated under P deficiency. The responses of PT genes to nutrient deficiencies and their roles in Pi uptake were further investigated in stylo. Four novel PT genes were identified in stylo and designated SgPT2 to SgPT5. Like SgPT1, which had been previously identified, all five SgPT proteins harboured the major facilitator superfamily (MFS) domain. Variations in tissue-specific expression were observed among the SgPT genes, which displayed diverse responses to deficiencies in nitrogen (N), P and potassium (K) in stylo roots. Four of the five SgPTs exhibited high levels of transcriptional responsiveness to P deficiency in roots. Furthermore, SgPT1, a Pi-starvation-induced gene closely related to legume PT homologues that participate in Pi transport, was selected for functional analysis. SgPT1 was localized to the plasma membrane. Analysis of transgenic Arabidopsis showed that overexpression of SgPT1 led to increased Pi accumulation and promoted root growth in Arabidopsis plants. Taken together, the results of this study suggest the involvement of SgPTs in the stylo response to nutrient deprivation. SgPT1 might mediate Pi uptake in stylo, which is beneficial for root growth during P deficiency.

Histological characteristics, cell wall hydrolytic enzyme activity, and transcriptome analysis with seed shattering of Stylosanthes accessions.

Stylosanthes spp. (stylo) are annual or perennial legume forages that are widely grown as forage and cover crops in tropical and subtropical regions. However, the seed yield of stylo is very low due to serious seed shattering. In the present study, we found that, although seed shattering was common among the stylo accessions, the shattering rates were genetically different. Therefore, we first synthesized the morphological, histological characteristic, physiochemical, and transcriptome analyses to determine the seed shattering mechanism in stylo. In general, the stylo germplasm with shorter lobules and thicker stems had a lower seed shattering rate and a higher seed weight. The seed and seed stalk joint is the abscission zone in stylo. Multiplex histology and hydrolytic enzyme activity analysis showed that the tearing of the abscission zone occurs due to the intense enzymatic degradation of polygalacturonase and cellulase in the seed shattering-susceptible accession TF0275. cDNA libraries from the abscission zone tissues of TF0041 and TF0275 at 14, 21, and 28 days after flowering were constructed and sequenced. A total of 47,606 unigenes were annotated and 18,606 differentially expressed genes (DEGs) were detected, including 9,140 upregulated and 9,446 downregulated unigenes. Furthermore, the 26 candidate DEGs involved in lignin biosynthesis, cellulase synthesis, and plant hormone signal transduction were found at all three developmental stages. This study provides valuable insights for future mechanistic studies of seed shattering in stylo.

SgNramp1, a plasma membrane-localized transporter, involves in manganese uptake in Stylosanthes guianensis.

Transporters belonging to the natural resistance-associated macrophage protein (Nramp) family play important roles in metal uptake and homeostasis. Although Nramp members have been functionally characterized in plants, the role of Nramp in the important tropical forage legume Stylosanthes guianensis (stylo) is largely unknown. This study aimed to determine the responses of Nramp genes to metal stresses and investigate its metal transport activity in stylo. Five SgNramp genes were identified from stylo. Expression analysis showed that SgNramp genes exhibited tissue preferential expressions and diverse responses to metal stresses, especially for manganese (Mn), suggesting the involvement of SgNramps in the response of stylo to metal stresses. Of the five SgNramps, SgNramp1 displayed the highest expression in stylo roots. A close correlation between SgNramp1 expression and root Mn concentration was observed among nine stylo cultivars under Mn limited condition. The higher expression of SgNramp1 was correlated with a high Mn uptake in stylo. Subsequent subcellular localization analysis showed that SgNramp1 was localized to the plasma membrane. Furthermore, heterologous expression of SgNramp1 complemented the phenotype of the Mn uptake-defective yeast (Saccharomyces cerevisiae) mutant Δsmf1. Mn concentration in the yeast cells expressing SgNramp1 was higher than that of the empty vector control, suggesting the transport activity of SgNramp1 for Mn in yeast. Taken together, this study reveals that SgNramp1 is a plasma membrane-localized transporter responsible for Mn uptake in stylo.

Priming of soil organic carbon mineralization and its temperature sensitivity in response to vegetation restoration in a karst area of Southwest China.

Plant residue input alters native soil organic carbon (SOC) mineralization through the priming effect, which strongly controls C sequestration during vegetation restoration. However, the effects of different vegetation types on SOC priming and the underlying microbial mechanisms due to global warming are poorly understood. To elucidate these unknowns, the current study quantified soil priming effects using 13C-labeled maize residue amendments and analyzed the community structure and abundances in the soils of a vegetation succession gradient (maize field (MF), grassland (GL), and secondary forest (SF)) from a karst region under two incubation temperatures (15 °C and 25 °C). Results revealed that after 120 d of incubation, vegetation restoration increased the soil priming effects. Compared to MF, the priming effects of SF at 15 °C and 25 °C increased by 142.36 % and 161.09 %, respectively. This may be attributed to a high C/N ratio and low-N availability (NO3-), which supports the "microbial nitrogen mining" theory. Variations in soil priming were linked to changes in microbial properties. Moreover, with vegetation restoration, the relative abundance of Actinobacteria (copiotrophs) increased, while Ascomycota (oligotrophs) decreased, which accelerated native SOC decomposition. Co-occurrence network analysis indicated that the cooperative interactions of co-existing keystone taxa may facilitate SOC priming. Furthermore, structural equation modeling (SEM) indicated that changes in the priming effects were directly related to the fungal Shannon index and microbial biomass C (MBC), which were affected by soil C/N and NO3-. Warming significantly decreased soil priming, which may be attributed to the increase in microbial respiration (qCO2) and decreased MBC. The temperature sensitivity (Q10) of SOC mineralization was higher after residue amendment, but significant differences were not detected among the vegetation types. Collectively, our results indicated that the intensity of priming effects was dependent on vegetation type and temperature. Microbial community alterations and physicochemical interactions played important roles in SOC decomposition and sequestration.

Dissection of Crop Metabolome Responses to Nitrogen, Phosphorus, Potassium, and Other Nutrient Deficiencies.

Crop growth and yield often face sophisticated environmental stresses, especially the low availability of mineral nutrients in soils, such as deficiencies of nitrogen, phosphorus, potassium, and others. Thus, it is of great importance to understand the mechanisms of crop response to mineral nutrient deficiencies, as a basis to contribute to genetic improvement and breeding of crop varieties with high nutrient efficiency for sustainable agriculture. With the advent of large-scale omics approaches, the metabolome based on mass spectrometry has been employed as a powerful and useful technique to dissect the biochemical, molecular, and genetic bases of metabolisms in many crops. Numerous metabolites have been demonstrated to play essential roles in plant growth and cellular stress response to nutrient limitations. Therefore, the purpose of this review was to summarize the recent advances in the dissection of crop metabolism responses to deficiencies of mineral nutrients, as well as the underlying adaptive mechanisms. This review is intended to provide insights into and perspectives on developing crop varieties with high nutrient efficiency through metabolite-based crop improvement.

Integrated multi-omics analysis provides insights into genome evolution and phosphorus deficiency adaptation in pigeonpea (Cajanus cajan).

Pigeonpea (Cajanus cajan) is an important legume food crop and plays a crucial role in a secure food supply in many developing countries. Several previous studies have suggested that pigeonpea has great potential for phosphorus (P) deficiency tolerance, but little is known about the underlying mechanism. In this study, the physiological and molecular responses of pigeonpea roots to phosphate (Pi) starvation were investigated through integrating phenotypic, genomic, transcriptomic, metabolomic, and lipidomic analyses. The results showed that low-Pi treatment increased total root length, root surface area, and root acid phosphatase activity, and promoted the secretion of organic acids (e.g. citric acids, piscidic acids, and protocatechuic acids) and the degradation of phospholipids and other P-containing metabolites in the roots of pigeonpea. Consistent with the morphological, physiological, and biochemical changes, a large number of genes involved in these Pi-starvation responses were significantly upregulated in Pi-deficient pigeonpea roots. Among these Pi-starvation response genes upregulated by low-Pi treatment, four gene families were expanded through recent tandem duplication in the pigeonpea genome, namely phosphate transporter 1 (PHT1), phosphoethanolamine/phosphocholine phosphatase (PECP), fasciclin-like arabinogalactan protein (FLA), and glutamate decarboxylase (GAD). These gene families may be associated with Pi uptake from the soil, phospholipid recycling, root morphological remodeling, and regulation of organic acid exudation. Taken together, our results suggest that pigeonpea employs complex Pi-starvation responses to strengthen P acquisition and utilization during low-Pi stress. This study provides new insights into the genome evolution and P deficiency adaptation mechanism of pigeonpea.

Encapsulation of a Desmodium intortum Protein Isolate Pickering Emulsion of ß-Carotene: Stability, Bioaccesibility and Cytotoxicity.

Owing to their excellent characteristics, Pickering emulsions have been widely used in the development and the application of new carriers for embedding and for delivering active compounds. In this study, ß-carotene was successfully encapsulated in a Pickering emulsion stabilized using Desmodium intortum protein isolate (DIPI). The results showed that the encapsulation efficiencies of ß-carotene in the control group Tween 20 emulsion (TE) and the DIPI Pickering emulsion (DIPIPE) were 46.7 ± 2.5% and 97.3 ± 0.8%, respectively. After storage for 30 days at 25 °C and 37 °C in a dark environment, approximately 79.4% and 72.1% of ß-carotene in DIPIPE were retained. Compared with TE, DIPIPE can improve the stability of ß-carotene during storage. In vitro digestion experiments showed that the bioaccessibility rate of ß-carotene in DIPIPE was less than that in TE. Cytotoxicity experiments showed that DIPI and ß-carotene micelles within a specific concentration range exerted no toxic effects on 3T3 cells. These results indicate that DIPIPE can be used as a good food-grade carrier for embedding and transporting active substances to broaden the application of the protein-based Pickering emulsion system in the development of functional foods.

Chromosome-scale genome assembly provides insights into speciation of allotetraploid and massive biomass accumulation of elephant grass (Pennisetum purpureum Schum.).

Elephant grass (Pennisetum purpureum Schum) is an important forage, biofuels and industrial plant widely distributed in tropical and subtropical areas globally. It is characterized with robust growth and high biomass. We sequenced its allopolyploid genome and assembled 2.07 Gb into A' and B subgenomes of 14 chromosomes with scaffold N50 of 8.47 Mb, yielding a total of 77,139 genes. The allotetraploid speciation occurred approximately 15 Ma after the divergence between Setaria italica and Pennisetum glaucum, according to a phylogenetic analysis of Pennisetum species. Double whole-genome duplication (WGD) and polyploidization events resulted in large-scale gene expansion, especially in the key steps of growth and biomass accumulation. Integrated transcriptome profiling revealed the functional divergence between subgenomes A' and B. A' subgenome mainly contributed to plant growth, development and photosynthesis, whereas the B subgenome was primarily responsible for effective transportation and resistance to stimulation. Some key gene families related to cellulose biosynthesis were expanded and highly expressed in stems, which could explain the high cellulose content in elephant grass. Our findings provide deep insights into genetic evolution of elephant grass and will aid future biological research and breeding, even for other grasses in the family Poaceae.