Sugar sensing and signaling in plants

The cell colony development is connected with the accumulation of embryogenesis-related proteins and dynamic distribution of cell wall components in in vitro cultures of Fagopyrum tataricum and Fagopyrum esculentum

BACKGROUND

Due to the totipotency of plant cells, which allows them to reprogram from a differentiated to a dedifferentiated state, plants exhibit a remarkable regenerative capacity, including under in vitro culture conditions. When exposed to plant hormones, primarily auxins and cytokinins, explant cells cultured in vitro can undergo differentiation through callus formation. Protoplast culture serves as a valuable research model for studying these processes in detail. This knowledge is particularly relevant for improving common and Tartary buckwheat species. To gain deeper insights into the stages of cell development from protoplasts-such as cell division, cell colony formation, and microcalli development-we focused on analyzing proteomes, cell wall composition, and changes in the expression profiles of selected genes in Fagopyrum protoplast cultures.

RESULTS

The results demonstrate a significant accumulation of somatic embryogenesis-related proteins like late embryogenesis abundant proteins (embryogenic protein-DC-8-like, seed biotin-containing protein) and endochitinases during the developmental path of protoplast-derived cultures. Additionally, we noted an extensive increase in seed storage proteins like vicilin, oleosins, and seed biotin-containing proteins during the culture. Investigation of somatic embryogenesis-associated transcription factors revealed massive up-regulation of LEAFY COTYLEDON1 for the 50th day of F. tataricum protoplast-derived cultures. However, for BABY BOOM, the transcription factor was noted to be down-regulated during the development of cell colonies. Furthermore, we demonstrated the variable distribution of cell wall components like pectin side chains, arabinogalactan proteins (AGPs) and extensins (EXTs), indicating the reorganisation of cell wall composition during the culture period.

CONCLUSIONS

This study revealed changes correlating with regaining embryogenic competence during the development of Fagopyrum protoplast-derived cell colonies. Our findings revealed variable expression levels of genes and proteins associated with somatic embryogenesis. This analysis identified an increase in seed storage proteins that play a significant role in the somatic somatic embryogenesis pathway of regeneration. Furthermore, the relationship between transcription factors and these processes seems to be connected with regaining somatic cells' totipotency and promoting embryogenic competence of protoplast-derived cell colonies. Additionally, we observed dynamic changes in cell wall composition during the development of the protoplast-derived cultures.

CLINICAL TRIAL NUMBER

Not applicable.

Interplay Between Phytohormones and Sugar Metabolism in Dendrocalamus latiflorus

Dendrocalamus latiflorus, a species of giant bamboo, holds significant ecological and economic value. This review delves into the intricate interplay between phytohormones and sugar metabolism in Dendrocalamus latiflorus, emphasizing species-specific mechanisms that enhance its ecological adaptability and rapid growth. By synthesizing recent research, this work highlights how phytohormones, including auxins, cytokinins, and abscisic acid, regulate sugar metabolism pathways such as glycolysis and starch degradation in response to environmental stimuli. These hormones influence crucial plant processes, including cell division, elongation, stress responses, and sugar metabolism pathways such as glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation. Geographic variations in these processes are examined, demonstrating their role in environmental adaptation and ecological resilience. For instance, populations in nutrient-rich soils exhibit enhanced cytokinin activity and sugar transport efficiency, while those in water-limited areas display elevated abscisic acid levels, aiding drought tolerance. This targeted focus on D. latiflorus provides novel insights into its potential applications in sustainable forestry and agroforestry systems. By integrating recent advances, this review highlights the critical role of phytohormone-sugar interplay in improving the productivity and stress resilience of D. latiflorus, with implications for agroforestry systems and climate change adaptation.

β-Glucan content increase in Waxy-mutated barley is closely associated with positive stress responses and is regulated by ASR1

Mixed-linkage (1,3; 1,4)-β-D-glucan (MLG) impacts the food and industrial end-uses of barley, but the molecular mechanism of variations in MLG content remains unclear. MLG content usually increases in Waxy-mutated barley. This study applied transcriptomic, proteomic, and metabolomic analyses to Waxy-mutated recombinant inbred lines with higher MLG content and wild-type lines with lower MLG content, and identified candidate genes and pathways regulating MLG content through combining preliminary gene function analysis. MLG biosynthesis differed significantly during late grain development in the Waxy-mutated and wild-type barley lines. The MLG increase was closely associated with strongly active sugar and starch metabolism and stress-responsive plant hormones, particularly abscisic acid (ABA) signaling process. Stress-responsive transcript factors ILR3, BTF3, RGGA, and PR13 protein bind to CslF6, which is critical for barley MLG biosynthesis, and the stress-responsive gene ASR1 also had a positive effect on MLG increase. Waxy mutation enhances barley stress responses by activating ABA- or other stress-responsive plant hormones signaling processes, which facilitates MLG biosynthesis. This study provides a new approach for elucidating the variations in MLG content of barley grains.

Unraveling the occurrence of hyperhydricity in oil palm somatic embryos during somatic embryogenesis process

The propagation of oil palm through somatic embryogenesis is the most effective method of cloning this palm tree; however, in vitro cultivation can lead to abnormalities in plant tissue, such as hyperhydricity. The present study aimed to evaluate the difference in anatomical, morphological, and histochemical characteristics, and gene expression in normal (Nm) and hyperhydric (Hh) somatic embryos of oil palm. For this purpose, Nm and Hh somatic embryos were collected from the differentiation medium and were submitted to anatomical and histochemical analyses to assess the nucleus/cytoplasm ratio (toluidine blue), starch (Lugol), and proteins (XP), as well as ultrastructural analyses via transmission electron microscopy. Additionally, gene expression analyses were performed to gain a better understanding on the molecular aspect of hyperhydric abnormality. A higher quantity of differentiated Nm somatic embryos per explant was observed, with a germination rate close to zero in Hh somatic embryos. Additionally, a higher accumulation of proteins and starch was found in Nm somatic embryos when compared to Hh embryos. It was also noted that in Nm somatic embryos, protein reserves were primarily located in the proximal region (embryonic axis), whereas starch reserves were mainly accumulated in the distal region of the somatic embryos. Hh somatic embryos exhibit insignificant starch reserves, and a greater number of intercellular spaces were observed compared to Nm somatic embryos. However, some Hh somatic embryos displayed histochemical characteristics similar to Nm, which could explain the occurrence of reversions from the Hh state to the Nm state observed in this study. Regarding molecular analyses, the gene expression results obtained showed that out of the 19 genes analyzed, 17 were upregulated in hyperhydric embryos when compared to the control condition (normal somatic embryos). Genes involved in stress response, energy metabolism, defense, membrane transport, hormonal regulation, and development were positively regulated, especially those involved in ethylene synthesis and energetic metabolism. To the best of our knowledge, this is the first in-depth study addressing hyperhydricity in oil palm during somatic embryogenesis.

Carotenoid-carbohydrate crosstalk: evidence for genetic and physiological interactions in storage tissues across crop species

Carotenoids play essential roles in photosynthesis, photoprotection, and human health. Efforts to increase carotenoid content in several staple crops have been successful through both conventional selection and genetic engineering methods. Interestingly, in some cases, altering carotenoid content has had unexpected effects on other aspects of plant metabolism, impacting traits like sugar content, dry matter percentage, fatty acid content, stress tolerance, and phytohormone concentrations. Studies across several diverse crop species have identified negative correlations between carotenoid and starch contents, as well as positive correlations between carotenoids and soluble sugars. Collectively, these reports suggest a metabolic interaction between carotenoids and carbohydrates. We synthesize evidence pointing to four hypothesized mechanisms: (1) direct competition for precursors; (2) physical interactions in plastids; (3) influences of sugar or apocarotenoid signaling networks; and (4) nonmechanistic population or statistical sources of correlations. Though the carotenoid biosynthesis pathway is well understood, the regulation and interactions of carotenoids, especially in nonphotosynthetic tissues, remain unclear. This topic represents an underexplored interplay between primary and secondary metabolism where further research is needed.

The Effects of Lead and Cross-Talk Between Lead and Pea Aphids on Defence Responses of Pea Seedlings

The main goal of this study was to investigate the effect of lead (Pb) at various concentrations, as an abiotic factor, and the cross-talk between Pb and pea aphid (Acyrthosiphon pisum (Harris)) (Hemiptera: Aphididae), as a biotic factor, on the defence responses of pea seedlings (Pisum sativum L. cv. Cysterski). The analysis of growth parameters for pea seedlings demonstrated that Pb at a low concentration, i.e., 0.025-0.0625 mM Pb(NO3)2, caused a hormesis effect, i.e., stimulation of seedling growth, whereas Pb at higher concentrations, i.e., 0.01-0.325 mM Pb(NO3)2, inhibited growth, which manifested as the inhibition of length and fresh biomass. The differences in the level of the main defence-related phytohormones, such as abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA), and indole-3-acetic acid (IAA)-an auxin stimulating plant cell growth-depended on the dose of Pb, aphid infestation and direct contact of the stress factor with the organ. A high accumulation of soluble sugars in the organs of pea seedlings both at sublethal doses and hormetic doses at early experimental time points was observed. At 0 h and 24 h of the experiment, the hormetic doses of Pb significantly stimulated invertase activities, especially in the roots. Moreover, an increase was observed in the pisatin concentration in pea seedlings growing in the presence of different concentrations of Pb and in the case of cross-talk between Pb and A. pisum in relation to the control. Additionally, a significant induction of the expressions of isoflavone synthase (IFS) and 6α-hydroxymaackiain 3-O-methyltransferase (HMM) genes, which participate in the regulation of the pisatin biosynthesis pathway, in pea seedlings growing under the influence of sublethal 0.5 mM Pb(NO3)2 and hormetic 0.075 mM Pb(NO3)2 doses of Pb was noted. The obtained results showed that the response of P. sativum seedlings depends on the Pb dose applied, direct contact of the stress factor with the organ and the duration of contact.

Nuclear-localized pyruvate kinases control phosphorylation of histone H3 on threonine 11

Phosphorylation of histone H3 at threonine 11 (H3T11ph) affects transcription and chromosome stability. However, the enzymes responsible for depositing H3T11ph and the functions of H3T11ph in plants remain unknown. Here we report that in Arabidopsis thaliana, PYRUVATE KINASE 6 (PK6), PK7 and PK8 enter the nucleus under conditions of sufficient glucose and light exposure, where they interact with SWI2/SNF2-RELATED 1 COMPLEX 4 (SWC4) and phosphorylate H3 at threonine 11. Mutations in these kinases or knockdown of SWC4 resulted in FLC-dependent early flowering, short hypocotyls and short pedicels. Genome-wide, H3T11ph is highly enriched at transcription start sites and transcription termination sites, and positively correlated with gene transcript levels. PK6 and SWC4 targeted FLC, MYB73, PRE1, TCP4 and TCP10, depositing H3T11ph at these loci and promoting their transcription, and PK6 occupancy at these loci requires SWC4. Together, our results reveal that nuclear-localized PK6, PK7 and PK8 modulate H3T11ph and plant growth.

Harnessing de novo transcriptome sequencing to identify and characterize genes regulating carbohydrate biosynthesis pathways in Salvia guaranitica L

Introduction

Carbohydrate compounds serve multifaceted roles, from energy sources to stress protectants, found across diverse organisms including bacteria, fungi, and plants. Despite this broad importance, the molecular genetic framework underlying carbohydrate biosynthesis pathways, such as starch, sucrose, and glycolysis/gluconeogenesis in Salvia guaranitica, remains largely unexplored.

Methods

In this study, the Illumina-HiSeq 2500 platform was used to sequence the transcripts of S. guaranitica leaves, generating approximately 8.2 Gb of raw data. After filtering and removing adapter sequences, 38 million reads comprising 210 million high-quality nucleotide bases were obtained. De novo assembly resulted in 75,100 unigenes, which were annotated to establish a comprehensive database for investigating starch, sucrose, and glycolysis biosynthesis. Functional analyses of glucose-6-phosphate isomerase (SgGPI), trehalose-6-phosphate synthase/phosphatase (SgT6PS), and sucrose synthase (SgSUS) were performed using transgenic Arabidopsis thaliana.

Results

Among the unigenes, 410 were identified as putatively involved in these metabolic pathways, including 175 related to glycolysis/gluconeogenesis and 235 to starch and sucrose biosynthesis. Overexpression of SgGPI, SgT6PS, and SgSUS in transgenic A. thaliana enhanced leaf area, accelerated flower formation, and promoted overall growth compared to wild-type plants.

Discussion

These findings lay a foundation for understanding the roles of starch, sucrose, and glycolysis biosynthesis genes in S. guaranitica, offering insights into future metabolic engineering strategies for enhancing the production of valuable carbohydrate compounds in S. guaranitica or other plants.

Whole-Genome Resequencing Identifies SNPs in Sucrose Synthase and Sugar Transporter Genes Associated with Sweetness in Coconut

Coconut (Cocos nucifera L.) is an important agricultural commodity with substantial economic and nutritional value, widely used for various products, including coconut water. The sweetness is an important quality trait of coconut water, which is influenced by genetic and environmental factors. In this study, we utilized next-generation sequencing to identify genetic variations in the coconut genome associated with the sweetness of coconut water. Whole-genome resequencing of 49 coconut accessions, including diverse germplasm and an F2 population of 81 individuals, revealed ~27 M SNPs and ~1.5 M InDels. Sugar content measured by °Bx was highly variable across all accessions tested, with dwarf varieties generally sweeter. A comprehensive analysis of the sugar profiles revealed that sucrose was the major sugar contributing to sweetness. Allele mining of the 148 genes involved in sugar metabolism and transport and genotype-phenotype association tests revealed two significant SNPs in the hexose carrier protein (Cnu01G018720) and sucrose synthase (Cnu09G011120) genes associated with the higher sugar content in both the germplasm and F2 populations. This research provides valuable insights into the genetic basis of coconut sweetness and offers molecular markers for breeding programs aimed at improving coconut water quality. The identified variants can improve the selection process in breeding high-quality sweet coconut varieties and thus support the economic sustainability of coconut cultivation.

Analysis of the Correlation between Persimmon Fruit-Sugar Components and Taste Traits from Germplasm Evaluation

Persimmon fruits are brightly colored and nutritious and are fruits that contain large amounts of sugar, vitamins, mineral elements, and phenolic substances. The aim of this study was to explore the differences in fruit-sugar components of different persimmon germplasms and their relationships with phenotypic and flavor indices through the determination of phenotypes and sugar components and through electronic-tongue indices, which provided the basis and inspiration for the selection of different sugar-accumulating types of persimmon fruits and the selection of high-sugar persimmon varieties. Our results showed that persimmon germplasm fruit-sugar components were dominated by sucrose, glucose and fructose and that the remaining sugar components were more diverse but less distributed among the various germplasm types. Based on the proportion of each sugar component in the fruit, persimmon germplasms can be categorized into sucrose-accumulating and reduced-sugar-accumulation types. Sucrose-accumulating types are dominated by sucrose, galactose, fucose and inositol, while reduced-sugar-accumulation types are dominated by glucose, fructose, mannose-6-phosphate, and xylose. The content of sugar components in the germplasm persimmon of fruits of different types and maturity periods of also differed, with significant differences in sugar components between PCNA (pollination-constant non-astringent) and PCA (pollination-constant astringent) fruits. Cluster analysis classified 81 persimmon germplasms into three clusters, including cluster I-A, with low glucose and fructose content, and cluster I-B, with medium glucose, fructose, and sucrose contents. Cluster II was high in sucrose and fructose. Cluster III had high contents of glucose and fructose and low contents of sucrose and inositol.

Carbohydrate distribution via SWEET17 is critical for Arabidopsis inflorescence branching under drought

Sugars Will Eventually be Exported Transporters (SWEETs) are the most recently discovered family of plant sugar transporters. By acting as uniporters, SWEETs facilitate the diffusion of sugars across cell membranes and play an important role in various physiological processes such as abiotic stress adaptation. AtSWEET17, a vacuolar fructose facilitator, was shown to be involved in the modulation of the root system during drought. In addition, previous studies have shown that overexpression of an apple homolog leads to increased drought tolerance in tomato plants. Therefore, SWEET17 might be a molecular element involved in plant responses to drought. However, the role and function of SWEET17 in above-ground tissues of Arabidopsis under drought stress remain elusive. By combining gene expression analysis and stem architecture with the sugar profiles of different above-ground tissues, we uncovered a putative role for SWEET17 in carbohydrate supply and thus cauline branch elongation, especially during periods of carbon limitation, as occurs under drought stress. Thus, SWEET17 seems to be involved in maintaining efficient plant reproduction under drought stress conditions.

Spliceosomal complex components are critical for adjusting the C:N balance during high-light acclimation

Plant acclimation to an ever-changing environment is decisive for growth, reproduction, and survival. Light availability limits biomass production on both ends of the intensity spectrum. Therefore, the adjustment of plant metabolism is central to high-light (HL) acclimation, and the accumulation of photoprotective anthocyanins is commonly observed. However, mechanisms and factors regulating the HL acclimation response are less clear. Two Arabidopsis mutants of spliceosome components exhibiting a pronounced anthocyanin overaccumulation in HL were isolated from a forward genetic screen for new factors crucial for plant acclimation. Time-resolved physiological, transcriptome, and metabolome analysis revealed a vital function of the spliceosome components for rapidly adjusting gene expression and metabolism. Deficiency of INCREASED LEVEL OF POLYPLOIDY1 (ILP1), NTC-RELATED PROTEIN1 (NTR1), and PLEIOTROPIC REGULATORY LOCUS1 (PRL1) resulted in a marked overaccumulation of carbohydrates and strongly diminished amino acid biosynthesis in HL. While not generally limited in N-assimilation, ilp1, ntr1, and prl1 showed higher glutamate levels and reduced amino acid biosynthesis in HL. The comprehensive analysis reveals a function of the spliceosome components in the conditional regulation of the carbon:nitrogen balance and the accumulation of anthocyanins during HL acclimation. The importance of gene expression, metabolic regulation, and re-direction of carbon towards anthocyanin biosynthesis for HL acclimation are discussed.

From acidity to sweetness: a comprehensive review of carbon accumulation in grape berries

Most of the carbon found in fruits at harvest is imported by the phloem. Imported carbon provide the material needed for the accumulation of sugars, organic acids, secondary compounds, in addition to the material needed for the synthesis of cell walls. The accumulation of sugars during fruit development influences not only sweetness but also various parameters controlling fruit composition (fruit "quality"). The accumulation of organic acids and sugar in grape berry flesh cells is a key process for berry development and ripening. The present review presents an update of the research on grape berry development, anatomical structure, sugar and acid metabolism, sugar transporters, and regulatory factors.

Exploring the relationship between pollen viability and inclusion in Paeonia lactiflora after cryopreservation

Pollen, as the male gametophyte, carries half of plant genetic information and is an important source of germplasm. The cryopreservation of pollen can not only preserve germplasm, but also solve the problem of time and space barrier in crossbreeding. So it is of great significance to explore the mechanism of pollen viability maintenance after cryopreservation. In this paper, 10 cultivars of Paeonia lactiflora with different fresh pollen viability that did not change after cryopreservation were taken as objects and the effects of pollen inclusions such as soluble sugar, starch, soluble protein, free amino acids, and proline were explored. The results showed that: (1) The contents of pollen inclusions in the fresh pollen of 10 cultivars were different. After cryopreservation, the contents of starch and free amino acids significantly decreased in 10 cultivars, and the soluble sugar, soluble protein, and proline varied with cultivars. (2) Correlation analysis showed that fresh pollen viability was significantly positively correlated with the soluble sugar (R-values of 0.630) and starch content (R-values of 0.694) in fresh pollen. But after cryopreservation pollen viability was only significantly positively correlated with the starch content (R-values of 0.725). These results suggest that the effects of pollen inclusions on pollen vitality are different before and after cryopreservation. The fresh pollen with higher soluble sugar and starch is more vital. But after cryopreservation, the pollen with high starch content has higher viability. The maintenance of stable pollen viability after cryopreservation appears to be related to starch content or starch metabolism, which requires further to study for a final determination.

Effect of Low Temperature on Content of Primary Metabolites in Two Wheat Genotypes Differing in Cold Tolerance

The study of cold-tolerance mechanisms of wheat as a leading cereal crop is very relevant to science. Primary metabolites play an important role in the formation of increased cold tolerance. The aim of this research is to define changes in the content of primary metabolites (soluble proteins and sugars), growth, and photosynthetic apparatus of freezing-tolerant and cold-sustainable wheat (Triticum aestivum L.) genotypes under optimal conditions and after prolonged (7 days) exposure to low temperature (4 °C). In order to gain a deeper comprehension of the mechanisms behind wheat genotypes' adaptation to cold, we determined the expression levels of photosynthetic genes (RbcS, RbcL) and genes encoding cold-regulated proteins (Wcor726, CBF14). The results indicated different cold-adaptation strategies of freezing-tolerant and cold-sustainable wheat genotypes, with soluble proteins and sugars playing a significant role in this process. In plants of freezing-tolerant genotypes, the strategy of adaptation to low temperature was aimed at increasing the content of soluble proteins and modification of carbohydrate metabolism. The accumulation of sugars was not observed in wheat of cold-sustainable genotypes during chilling, but a high content of soluble proteins was maintained both under optimal conditions and after cold exposure. The adaptation strategies of wheat genotypes differing in cold tolerance were related to the expression of photosynthetic genes and genes encoding cold-regulated proteins. The data improve our knowledge of physiological and biochemical mechanisms of wheat cold adaptation.

Growth and Phytochemistry of Cymbopogon citratus Stapf Inoculated with Plant Growth-Promoting Bacteria under Different Lead Levels

This study aimed to investigate the phytochemistry of lemongrass (Cymbopogon citratus) inoculated with Azospirillum brasilense and grown in lead (Pb)-contaminated soil to assess its responses to inoculation under different Pb levels. The experimental design was completely randomized in a 2 × 5 factorial scheme: two levels of A. brasilense (absence or presence) and five Pb levels. After four months of treatment, the following were analyzed: total and reducing sugars, total phenolic content, flavonoids, antioxidant activity, antioxidant enzymes, proline, and essential oil (EO) content and composition. Soil Pb levels and A. brasilense inoculation affected phytochemicals in lemongrass plants. Azospirillum inoculation reduced total sugars in the roots at all soil Pb levels, while increasing Pb levels favored a rise in sugar contents. There was an increase in flavonoid content in treatments associated with Pb and inoculated with A. brasilense. Antioxidant capacity was lower at lower Pb levels, regardless of bacterial inoculation. Enzymatic response was mainly affected by Pb concentrations between 50 and 100 mg kg-1 soil. EO content was influenced by soil Pb levels, with higher EO production at 500 mg Pb kg-1 soil and without A. brasilense inoculation. Overall, lemongrass cultivation in Pb-contaminated areas can be an alternative to phytoremediation and EO production for the industry.

Transcription factor OsMYB30 increases trehalose content to inhibit α-amylase and seed germination at low temperature

Low-temperature germination (LTG) is an important agronomic trait for direct-seeding cultivation of rice (Oryza sativa). Both OsMYB30 and OsTPP1 regulate the cold stress response in rice, but the function of OsMYB30 and OsTPP1 in regulating LTG and the underlying molecular mechanism remains unknown. Employing transcriptomics and functional studies revealed a sugar signaling pathway that regulates seed germination in response to low temperature (LT). Expression of OsMYB30 and OsTPP1 was induced by LT during seed germination, and overexpressing either OsMYB30 or OsTPP1 delayed seed germination and increased sensitivity to LT during seed germination. Transcriptomics and qPCR revealed that expression of OsTPP1 was upregulated in OsMYB30-overexpressing lines but downregulated in OsMYB30-knockout lines. In vitro and in vivo experiments revealed that OsMYB30 bound to the promoter of OsTPP1 and regulated the abundance of OsTPP1 transcripts. Overaccumulation of trehalose (Tre) was found in both OsMYB30- and OsTPP1-overexpressing lines, resulting in inhibition of α-amylase 1a (OsAMY1a) gene during seed germination. Both LT and exogenous Tre treatments suppressed the expression of OsAMY1a, and the osamy1a mutant was not sensitive to exogenous Tre during seed germination. Overall, we concluded that OsMYB30 expression was induced by LT to activate the expression of OsTPP1 and increase Tre content, which thus inhibited α-amylase activity and seed germination. This study identified a phytohormone-independent pathway that integrates environmental cues with internal factors to control seed germination.

Bio-stimulants from medicinally and nutritionally significant plant extracts mitigate drought adversities in Zea mays through enhanced physiological, biochemical, and antioxidant activities

Drought stress poses a substantial threat to global plant productivity amid increasing population and rising agricultural demand. To overcome this problem, the utilization of organic plant growth ingredients aligns with the emphasis on eco-friendly farming practices. Therefore, the present study aimed to assess the influence of 30 botanical extracts on seed germination, seedling vigor, and subsequent maize plant growth under normal and water deficit conditions. Specifically, eight extracts showed significant enhancement in agronomical parameters (ranging from ∼2 % to ∼ 183 %) and photosynthetic pigments (ranging from ∼21 % to ∼ 195 %) of seedlings under drought conditions. Extended tests on maize in a greenhouse setting confirmed that the application of six extracts viz Moringa oleifera leaf (MLE), bark (MBE), Terminalia arjuna leaf (ALE), bark (ABE), Aegel marmelos leaf (BLE), and Phyllanthus niruri leaf (AmLE) improved plant growth and drought tolerance, as evident in improved physio-biochemical parameters. GC-MS analysis of the selected extracts unveiled a total of 51 bioactive compounds, including sugars, sugar alcohols, organic acids, and amino acids, and might be playing pivotal roles in plant acclimatization to drought stress. In conclusion, MLE, MBE, BLE, and ABE extracts exhibit significant potential for enhancing seedling establishment and growth in maize under both normal and water deficit conditions.

The mechanisms behind the contrasting responses to waterlogging in black-grass (Alopecurus myosuroides) and wheat (Triticum aestivum)

Black-grass (Alopecurus myosuroides ) is one of the most problematic agricultural weeds of Western Europe, causing significant yield losses in winter wheat (Triticum aestivum ) and other crops through competition for space and resources. Previous studies link black-grass patches to water-retaining soils, yet its specific adaptations to these conditions remain unclear. We designed pot-based waterlogging experiments to compare 13 biotypes of black-grass and six cultivars of wheat. These showed that wheat roots induced aerenchyma when waterlogged whereas aerenchyma-like structures were constitutively present in black-grass. Aerial biomass of waterlogged wheat was smaller, whereas waterlogged black-grass was similar or larger. Variability in waterlogging responses within and between these species was correlated with transcriptomic and metabolomic changes in leaves of control or waterlogged plants. In wheat, transcripts associated with regulation and utilisation of phosphate compounds were upregulated and sugars and amino acids concentrations were increased. Black-grass biotypes showed limited molecular responses to waterlogging. Some black-grass amino acids were decreased and one transcript commonly upregulated was previously identified in screens for genes underpinning metabolism-based resistance to herbicides. Our findings provide insights into the different waterlogging tolerances of these species and may help to explain the previously observed patchiness of this weed's distribution in wheat fields.

Leaf senescence attributes: the novel and emerging role of sugars as signaling molecules and the overlap of sugars and hormones signaling nodes

Sugars are the primary products of photosynthesis and play multiple roles in plants. Although sugars are usually considered to be the building blocks of energy storage and carbon transport molecules, they have also gradually come to be acknowledged as signaling molecules that can initiate senescence. Senescence is an active and essential process that occurs at the last developmental stage and corresponds to programmed degradation of: cells, tissues, organs, and entire organisms. It is a complex process involving: numerous biochemical changes, transporters, genes, and transcription factors. The process is controlled by multiple developmental signals, among which sugar signals are considered to play a vital role; however, the regulatory pathways involved are not fully understood. The dynamic mechanistic framework of sugar accumulation has an inconsistent effect on senescence through the sugar signaling pathway. Key metabolizing enzymes produce different sugar signals in response to the onset of senescence. Diverse sugar signal transduction pathways and a variety of sugar sensors are involved in controlling leaf senescence. This review highlights the processes underlying initiation of sugar signaling and crosstalk between sugars and hormones signal transduction pathways affecting leaf senescence. This summary of the state of current knowledge across different plants aids in filling knowledge gaps and raises key questions that remain to be answered with respect to regulation of leaf senescence by sugar signaling pathways.

Exploring sustainable alternatives: Wood distillate alleviates the impact of bioplastic in basil plants

The growing interest in bioplastics and bio-based crop management products in agriculture is driven by the Sustainable Development Goals of the 2030 Agenda. However, recent research has raised concerns about the sustainability of bioplastics due to their potential negative impact on crop growth and yield, with implications for the environment and human health. In this study, wood distillate (WD) was evaluated as a natural enhancer of plant growth and defence system to mitigate the negative impact of a starch-based bioplastic on basil (Ocimum basilicum L.) plants. The study analyzed physiological and biochemical changes in basil plants subjected for 35 days to single or combined treatments of WD and bioplastic by measuring biomarkers of healthy growth, such as soluble proteins, sugars, vitamin C, and malondialdehyde (MDA). The results showed that WD promoted basil development, whereas the presence of bioplastic hindered it. Interestingly, WD did not affect sugars but increased vitamin C by 12 %, which is considered a positive effect as changes in sugar levels could indicate plant stress. In contrast, bioplastic resulted in reduced sugars (-41 %) and increased (+17 %) MDA level, while vitamin C content remained unchanged. However, when WD was added to plants grown with bioplastic, it elevated the levels of all examined parameters, except for sugars and vitamin C, which experienced reductions (-66 % and 33 %, respectively). Intriguingly, despite this reduction, the observed direct correlation between sugar and vitamin C contents was maintained, indicating that the decrease in sugar content may have reached a critical threshold. This study suggests that the use of WD has the potential to alleviate the adverse effects of bioplastic on basil growth and development and highlights the importance of adopting sustainable practices in agriculture, as well as the need for a critical assessment of the environmental impact of new technologies and products.

How metabolism and development are intertwined in space and time

Developmental transitions, occurring throughout the life cycle of plants, require precise regulation of metabolic processes to generate the energy and resources necessary for the committed growth processes. In parallel, the establishment of new cells, tissues, and even organs, alongside their differentiation provoke profound changes in metabolism. It is increasingly being recognized that there is a certain degree of feedback regulation between the components and products of metabolic pathways and developmental regulators. The generation of large-scale metabolomics datasets during developmental transitions, in combination with molecular genetic approaches has helped to further our knowledge on the functional importance of metabolic regulation of development. In this perspective article, we provide insights into studies that elucidate interactions between metabolism and development at the temporal and spatial scales. We additionally discuss how this influences cell growth-related processes. We also highlight how metabolic intermediates function as signaling molecules to direct plant development in response to changing internal and external conditions.

Physiological Comparison of Two Salt-Excluder Hybrid Grapevine Rootstocks under Salinity Reveals Different Adaptation Qualities

Like other plant stresses, salinity is a central agricultural problem, mainly in arid or semi-arid regions. Therefore, salt-adapted plants have evolved several adaptation strategies to counteract salt-related events, such as photosynthesis inhibition, metabolic toxicity, and reactive oxygen species (ROS) formation. European grapes are usually grafted onto salt-tolerant rootstocks as a cultivation practice to alleviate salinity-dependent damage. In the current study, two grape rootstocks, 140 Ruggeri (RUG) and Millardet et de Grasset 420A (MGT), were utilized to evaluate the diversity of their salinity adaptation strategies. The results showed that RUG is able to maintain higher levels of the photosynthetic pigments (Chl-T, Chl-a, and Chl-b) under salt stress, and hence accumulates higher levels of total soluble sugars (TSS), monosaccharides, and disaccharides compared with the MGT rootstock. Moreover, it was revealed that the RUG rootstock maintains and/or increases the enzymatic activities of catalase, GPX, and SOD under salinity, giving it a more efficient ROS detoxification machinery under stress.

Effects of drought and rehydration on root gene expression in seedlings of Pinus massoniana Lamb

The mechanisms underlying plant response to drought involve the expression of numerous functional and regulatory genes. Transcriptome sequencing based on the second- and/or third-generation high-throughput sequencing platforms has proven to be powerful for investigating the transcriptional landscape under drought stress. However, the full-length transcriptomes related to drought responses in the important conifer genus Pinus L. remained to be delineated using the third-generation sequencing technology. With the objectives of identifying the candidate genes responsible for drought and/or rehydration and clarifying the expression profile of key genes involved in drought regulation, we combined the third- and second-generation sequencing techniques to perform transcriptome analysis on seedling roots under drought stress and rewatering in the drought-tolerant conifer Pinus massoniana Lamb. A sum of 294,114 unique full-length transcripts were produced with a mean length of 3217 bp and N50 estimate of 5075 bp, including 279,560 and 124,438 unique full-length transcripts being functionally annotated and Gene Ontology enriched, respectively. A total of 4076, 6295 and 18,093 differentially expressed genes (DEGs) were identified in three pair-wise comparisons of drought-treatment versus control transcriptomes, including 2703, 3576 and 8273 upregulated and 1373, 2719 and 9820 downregulated DEGs, respectively. Moreover, 157, 196 and 691 DEGs were identified as transcription factors in the three transcriptome comparisons and grouped into 26, 34 and 44 transcription factor families, respectively. Gene Ontology enrichment analysis revealed that a remarkable number of DEGs were enriched in soluble sugar-related and cell wall-related processes. A subset of 75, 68 and 97 DEGs were annotated to be associated with starch, sucrose and raffinose metabolism, respectively, while 32 and 70 DEGs were associated with suberin and lignin biosynthesis, respectively. Weighted gene co-expression network analysis revealed modules and hub genes closely related to drought and rehydration. This study provides novel insights into root transcriptomic changes in response to drought dynamics in Masson pine and serves as a fundamental work for further molecular investigation on drought tolerance in conifers.

In Vitro Evaluation of Biological and Anticancer Activities Exhibited by Five Varieties of Vitis vinifera L

Vitis vinifera commonly known as grapevine is one of the most important fruit crops worldwide. Its cultivation started more than 7000 years ago in the Near East, and over the millennia was followed by the development of thousands of cultivars that were further selected and characterized for specific purposes. Its important pharmacological value and its richness in phytoconstituents were the triggers to perform this project. Seven extracts were prepared from five different V. vinifera varieties (V. vinifera 'Black Pearl' (BP), V. vinifera 'Red Glob' (RG), V. vinifera 'Crimson' (CR), V. vinifera 'Beitamouni' (BE) and V. vinifera 'Superior' (SU)) by separating the pulp from the seeds, followed by methanolic extraction. The phytochemical analysis showed that red colored grapes (RE, BP and CR), the seeds from V. vinifera 'Black Pearl' and V. vinifera 'Red Globe' contain higher amounts of primary and secondary metabolites such as polyphenols, anthocyanins and reducing sugars. In addition to their richness in phytoconstituents, these varieties/seeds possess an important antioxidant activity. The results of the cell viability assays showed that the red varieties have a potential anticancer activity against Capan-2 pancreatic cancer and MDA-MB231(TNBC) breast cancer cell lines, with the greatest promise when combined with the seeds.

Genome-Wide Identification of GmSPS Gene Family in Soybean and Expression Analysis in Response to Cold Stress

Sucrose metabolism plays a critical role in development, stress response, and yield formation of plants. Sucrose phosphate synthase (SPS) is the key rate-limiting enzyme in the sucrose synthesis pathway. To date, genome-wide survey and comprehensive analysis of the SPS gene family in soybean (Glycine max) have yet to be performed. In this study, seven genes encoding SPS were identified in soybean genome. The structural characteristics, phylogenetics, tissue expression patterns, and cold stress response of these GmSPSs were investigated. A comparative phylogenetic analysis of SPS proteins in soybean, Medicago truncatula, Medicago sativa, Lotus japonicus, Arabidopsis, and rice revealed four families. GmSPSs were clustered into three families from A to C, and have undergone five segmental duplication events under purifying selection. All GmSPS genes had various expression patterns in different tissues, and family A members GmSPS13/17 were highly expressed in nodules. Remarkably, all GmSPS promoters contain multiple low-temperature-responsive elements such as potential binding sites of inducer of CBF expression 1 (ICE1), the central regulator in cold response. qRT-PCR proved that these GmSPS genes, especially GmSPS8/18, were induced by cold treatment in soybean leaves, and the expression pattern of GmICE1 under cold treatment was similar to that of GmSPS8/18. Further transient expression analysis in Nicotiana benthamiana and electrophoretic mobility shift assay (EMSA) indicated that GmSPS8 and GmSPS18 transcriptions were directly activated by GmICE1. Taken together, our findings may aid in future efforts to clarify the potential roles of GmSPS genes in response to cold stress in soybean.

Genome-wide identification, evolution and expression pattern analysis of the GATA gene family in Sorghum bicolor

The GATA family of transcription factors is zinc finger DNA binding proteins involved in a variety of biological processes, including plant growth and development and response to biotic/abiotic stresses, and thus play an essential role in plant response to environmental changes. However, the GATA gene family of Sorghum (SbGATA) has not been systematically analyzed and reported yet. Herein, we used a variety of bioinformatics methods and quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) to explore the evolution and function of the 33 SbGATA genes identified. These SbGATA genes, distributed on 10 chromosomes, are classified into four subfamilies (I-IV) containing one pair of tandem duplications and nine pairs of segment duplications, which are more closely related to the monocot Brachypodium distachyon and Oryza sativa GATA genes. The physicochemical properties of the SbGATAs are significantly different among the subfamilies, while the protein structure and conserved protein motifs are highly conserved in the subfamilies. In addition, the transcription of SbGATAs is tissue-specific during Sorghum growth and development, which allows for functional diversity in response to stress and hormones. Collectively, our study lays a theoretical foundation for an in-depth analysis of the functions, mechanisms and evolutionary relationships of SbGATA during plant growth and development.

Defence-related metabolic changes in wheat (Triticum aestivum L.) seedlings in response to infection by Puccinia graminis f. sp. tritici

Stem rust caused by the pathogen Puccinia graminis f. sp. tritici is a destructive fungal disease-causing major grain yield losses in wheat. Therefore, understanding the plant defence regulation and function in response to the pathogen attack is required. As such, an untargeted LC-MS-based metabolomics approach was employed as a tool to dissect and understand the biochemical responses of Koonap (resistant) and Morocco (susceptible) wheat varieties infected with two different races of P. graminis (2SA88 [TTKSF] and 2SA107 [PTKST]). Data was generated from the infected and non-infected control plants harvested at 14- and 21- days post-inoculation (dpi), with 3 biological replicates per sample under a controlled environment. Chemo-metric tools such as principal component analysis (PCA), orthogonal projection to latent structures-discriminant analysis (OPLS-DA) were used to highlight the metabolic changes using LC-MS data of the methanolic extracts generated from the two wheat varieties. Molecular networking in Global Natural Product Social (GNPS) was further used to analyse biological networks between the perturbed metabolites. PCA and OPLS-DA analysis showed cluster separations between the varieties, infection races and the time-points. Distinct biochemical changes were also observed between the races and time-points. Metabolites were identified and classified using base peak intensities (BPI) and single ion extracted chromatograms from samples, and the most affected metabolites included flavonoids, carboxylic acids and alkaloids. Network analysis also showed high expression of metabolites from thiamine and glyoxylate, such as flavonoid glycosides, suggesting multi-faceted defence response strategy by understudied wheat varieties towards P. graminis pathogen infection. Overall, the study provided the insights of the biochemical changes in the expression of wheat metabolites in response to stem rust infection.

Tomato SlSTK is involved in glucose response and regulated by the ubiquitin ligase SlSINA4

Glucose signaling plays an essential role in plant growth, development and stress response. Previous studies have shown that STOREKEEPER (STK) is a new class of DNA binding protein that regulates patatin expression in potato tubers and confers elevated sensitivity to glucose response in Arabidopsis thaliana. However, the biological functions of STK gene in tomato (Solanum lycopersicum) have not been studied. Here, we characterized the tomato SlSTK and determined its role in glucose signaling. The SlSTK protein was localized in the nucleus and the expression of the SlSTK gene was induced by the glucose treatment. Overexpression of SlSTK in tomato enhanced glucose sensitivity, as manifested by reduced seed germination rate and arrested growth at the early seedling stage. In contrast, the SlSTK-knockout plants generated via the clustered regularly interspaced short palindromic repeats (CRISPR) - CRISPR-associated protein 9 (CRISPR-Cas9) technique attenuated the sensitivity to glucose. In addition, SlSTK was ubiquitinated in plant cells and interacted with the tomato ubiquitin ligase SEVEN IN ABSENTIA4 (SlSINA4) that degrades SlSTK in a ligase-dependent manner. Taken together, these results suggest that SlSTK is involved in glucose signaling and its stability is regulated by the ubiquitin ligase SlSINA4.

Insights into the convergent evolution of fructan biosynthesis in angiosperms from the highly characteristic chicory genome

Fructans in angiosperms play essential roles in physiological functions and environmental adaptations. As a major source of industrial fructans (especially inulin-type), chicory (Cichorium intybus L.) is a model species for studying fructan biosynthesis. However, the genes underlying this process and their evolutionary history in angiosperms remain elusive. We combined multiple sequencing technologies to assemble and annotate the chicory genome and scan its (epi)genomic features, such as genomic components, DNA methylation, and three-dimensional (3D) structure. We also performed a comparative genomics analysis to uncover the associations between key traits and gene families. We achieved a nearly complete chicory genome assembly and found that continuous bursts of a few highly active retrotransposon families largely shaped the (epi)genomic characteristics. The highly methylated genome with its unique 3D structure potentially influences critical biological processes. Our comprehensive comparative genomics analysis deciphered the genetic basis for the rich sesquiterpene content in chicory and indicated that the fructan-accumulating trait resulted from convergent evolution in angiosperms due to shifts in critical sites of fructan-active enzymes. The highly characterized chicory genome provides insight into Asteraceae evolution and fructan biosynthesis in angiosperms.

Genome-wide analysis and characterization of Dendrocalamus farinosus SUT gene family reveal DfSUT4 involvement in sucrose transportation in plants

Sucrose is the main transported form of photosynthetic products. Sucrose transporter (SUT) participates in the translocation of sucrose from source to sink, which is important for the growth and development of plants. Dendrocalamus farinosus is an important economic crop in southwestern China because of its high growth rate, high fiber content, and dual usage for food and timber, but the mechanism of sucrose transportation in D. farinosus is unclear. In this study, a total of 12 SUT transporter genes were determined in D. farinosus by whole-genome identification. DfSUT2, DfSUT7, and DfSUT11 were homologs of rice OsSUT2, while DfSUT4 was a homolog of OsSUT4, and these four DfSUT genes were expressed in the leaf, internode, node, and bamboo shoots of D. farinosus. In addition, DfSUT family genes were involved in photosynthetic product distribution, ABA/MeJA responses, and drought resistance, especially DfSUT4. The function of DfSUT4 was then verified in Nicotiana tabacum. DfSUT4 was localized mainly in the leaf mesophyll and stem phloem of pDfSUT4::GUS transgenic plant. The overexpression of DfSUT4 gene in transgenic plant showed increases of photosynthetic rate, above-ground biomass, thousand grain weight, and cellulose content. Our findings altogether indicate that DfSUT4 can be a candidate gene that can be involved in phloem sucrose transportation from the source leaves to the sink organs, phytohormone responses, abiotic stress, and fiber formation in plants, which is very important in the genetic improvement of D. farinosus and other crops.

Iodine Biofortification and Seaweed Extract-Based Biostimulant Supply Interactively Drive the Yield, Quality, and Functional Traits in Strawberry Fruits

The horticultural sector is seeking innovative and sustainable agronomic practices which could lead to enhanced yield and product quality. Currently, plant biofortification is recognized as a valuable technique to improve microelement concentrations in plant tissues. Among trace elements, iodine (I) is an essential microelement for human nutrition. Concomitantly, the application of biostimulants may improve overall plant production and quality traits. With the above background in mind, an experiment was designed with the aim of assessing the interactive impact of a seaweed extract-based biostimulant (SwE) (0 mL L^-1 (served as control) or 3 mL L^-1 (optimal dosage)) and 0, 100, 300, or 600 mg L^-1 I on the growth parameters, yield, fruit quality, minerals, and functional characteristics of the tunnel-grown "Savana" strawberry. SwE foliar application improved the plant growth-related traits, total and marketable yield, fruit color parameters, soluble solids content, nitrogen (N), potassium (K), and magnesium (Mg) fruit concentrations. Furthermore, an enhancement in the fruit dry matter content, ascorbic acid, and I concentration in fruits was detected when the SwE supply interacted with a mild I dose (100 or 300 mg L^-1). The research underlined that combining SwE application and I biofortification increased the strawberry yield and quality and enhanced the plant nutritional status variation, thereby, determining a boosted strawberry I tolerance.

The functional analysis of sugar transporter proteins in sugar accumulation and pollen tube growth in pummelo (Citrus grandis)

Sugar transporter proteins (STPs) play vital roles in sugar transport and allocation of carbon sources in plants. However, the evolutionary dynamics of this important gene family and their functions are still largely unknown in citrus, which is the largest fruit crop in the world. In this study, fourteen non-redundant CgSTP family members were identified in pummelo (Citrus grandis). A comprehensive analysis based on the biochemical characteristics, the chromosomal location, the exon-intron structures and the evolutionary relationships demonstrated the conservation and the divergence of CgSTPs. Moreover, CgSTP4, 11, 13, 14 were proofed to be localized in plasma membrane and have glucose transport activity in yeast. The hexose content were significantly increased with the transient overexpression of CgSTP11 and CgSTP14. In addition, antisense repression of CgSTP4 induced the shorter pollen tube length in vitro, implying the potential role of CgSTP4 in pummelo pollen tube growth. Taken together, this work explored a framework for understanding the physiological role of CgSTPs and laid a foundation for future functional studies of these members in citrus species.

Physiological and biochemical responses of Limonium tetragonum to NaCl concentrations in hydroponic solution

Introduction

Limonium (L.) tetragonum (Thunb.) A. A. Bullock, a halophyte that grows all over the southwest coast of Korea, is a medicinal plant with various pharmacological effects. The salt defense mechanism stimulates the biosynthesis of various secondary metabolites and improves functional substances. In this study, we investigated the optimal NaCl concentration for the growth and enhancement of secondary metabolites in hydroponically grown L. tetragonum.

Methods

The seedlings grown for 3 weeks in a hydroponic cultivation system were treated with 0-, 25-, 50-, 75-, and 100-mM NaCl in Hoagland's nutrient solution for 8 weeks. No significant effect on the growth and chlorophyll fluorescence was observed for the NaCl concentrations below 100-mM.

Results and discussions

The increase in the NaCl concentration resulted in the decrease in the water potential of the L. tetragonum leaves. The Na⁺ content accumulated in the aerial part increased rapidly and the content of K⁺, which acts as an antagonist, decreased with the increase in NaCl concentrations in hydroponics. The total amino acid content of L. tetragonum decreased compared to the 0-mM NaCl, and most of the amino acid content decreased as the NaCl concentration increased. In contrast, the content of urea, proline (Pro), β-alanine, ornithine, and arginine was increased with an increase in NaCl concentration. The Pro content at 100-mM NaCl accounted for 60% of the total amino acids and was found to be a major osmoregulator as an important component of the salt defense mechanisms. The top five compounds identified in the L. tetragonum were classified as flavonoids while the flavanone compound was detected only in the NaCl treatments. A total of four myricetin glycosides were increased in comparison to the 0-mM NaCl. Among the differentially expressed genes, a significantly large change in Gene ontology was seen in the circadian rhythm. NaCl treatment enhanced the flavonoid-based substances of L. tetragonum. The optimum NaCl concentration for the enhancement of secondary metabolites of the L. tetragonum in the vertical farm-hydroponic cultivation system was 75-mM NaCl.

Response of sugar metabolism in the cotyledons and roots of Ricinus communis subjected to salt stress

Ricinus communis is an important oilseed crop worldwide and is also considered one of the best potential plants for salt-affected soil improvement in northeast China. However, little is known about photosynthesis and carbohydrate metabolism in this plant, nor the distribution of carbohydrates in cotyledons and roots under salinity stress. In the present study, seedling growth, gas exchange parameters (P_N , E, g_s and C_i ), carbohydrate (fructose, sucrose, glucose, soluble sugar and starch) metabolism and related enzymes and genes were measured in Ricinus plants. Under salt stress, P_N of cotyledons decreased significantly (P < 0.05), resulting in weak photosynthetic capacity. Furthermore, salt stress increased sucrose and glucose content in cotyledons, but decreased soluble sugar and starch content. However, sucrose increased and starch decreased in roots. This may be correlated with the increasing sugar metabolism under salinity, including notable changes in sugar-related enzyme activities (SPS, SuSy, α-amylase and β-amylase) and gene expression of RcINV, RcSUS, RcAmY, RcBAM and RcGBE1. The results suggest that salinity reduces photosynthesis of cotyledons, alters carbohydrate allocation between cotyledons and roots and also promotes starch utilization in cotyledons and starch biosynthesis in roots, leading to a functional imbalance between cotyledons and roots. Together, these findings provide insights into the crucial role of sugar metabolism in improving salt-tolerance of Ricinus during the early seedling growth stage.

Arabidopsis MPK3 and MPK6 regulates D-glucose signaling and interacts with G-protein, RGS1

Sugar as a signaling molecule has attracted lots of attention. Even though several kinases have been shown to play a crucial role in the sugar signaling and response to exogenous D-glucose (Glc), the information on the involvement of MAP kinase cascade in sugar signaling has remain largely unexplored. In this report we demonstrate that MAP kinase signaling is essential for sensitivity to higher concentrations of D-Glc in Arabidopsis. We found that D-Glc activates MAP kinases, MPK3 and MPK6 in a concentration and time-dependent manner. The mutants of mpk3 and mpk6 display hyposensitivity to 6% D-Glc during seed germination, cotyledon greening and root growth. Interestingly, the altered sensitivity to increased D-Glc is severely enhanced by addition of 1% Sucrose in the media. Our study also deciphered the role of one of the Glc sensor proteins, RGS1 that interacts and gets phosphorylated at its C-terminal domain by MPK3 and MPK6. Overall our study provides a new insight on the involvement of MAP kinases in association with G-proteins that might regulate sugar signaling and sugar responsive growth and development in Arabidopsis.

When to branch: seasonal control of shoot architecture in trees

Long-lived perennial plants optimize their shoot architecture by responding to seasonal cues. The main strategy used by plants of temperate and boreal regions with respect to surviving the extremely unfavourable conditions of winter comprises the protection of their apical and lateral meristematic tissues. This involves myriads of transcriptional, translational and metabolic changes in the plants because shoot architecture is controlled by multiple pathways that regulate processes such as bud formation and flowering, small RNAs, environmental factors (especially light quality, photoperiod and temperature), hormones, and sugars. Recent studies have begun to reveal how these pathways are recruited for the seasonal adaptation and regulation of shoot architecture in perennial plants, including the role of a regulatory module consisting of antagonistic players terminal flower 1 (TFL1) and like-ap1 (LAP1) in the hybrid aspen. Here, we review recent progress in our understanding of the genetic control of shoot architecture in perennials compared to in annuals.

Involvement of ethylene in melatonin-modified photosynthetic-N use efficiency and antioxidant activity to improve photosynthesis of salt grown wheat

The involvement of melatonin in the regulation of salt stress acclimation has been shown in plants in this present work. We found that the GOAL cultivar of wheat (Triticum aestivum L.) was the most salt-tolerant among the investigated cultivars, GOAL, HD-2967, PBW-17, PBW-343, PBW-550, and WH-1105 when screened for tolerance to 100 mM NaCl. The application of 100 μM melatonin maximally reduced oxidative stress and improved photosynthesis in the cv. GOAL. Melatonin supplementation reduced salt stress-induced oxidative stress by upregulating the activity of antioxidant enzymes, such as superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR), and reduced the glutathione (GSH) production. This resulted in increased membrane stability, photosynthetic-N use efficiency and photosynthesis in plants. The application of 50 μM of the ethylene biosynthesis inhibitor aminoethoxyvinylglycine (AVG) in the presence of melatonin and salt stress increased H₂ O₂ content but reduced GR activity and GSH, photosynthesis, and plant dry mass. This signifies that melatonin-mediated salt stress tolerance was related to ethylene synthesis as it improved antioxidant activity and photosynthesis of plants under salt stress. Thus, the interaction of melatonin and ethylene bears a prominent role in salt stress tolerance in wheat and can be used to develop salt tolerance in other crops.

Effect of Salicylic Acid and Pre-Cold Treatment on Flower Induction in Saffron

Saffron is an important flowering plant, generally known as a golden condiment. The present study was performed to find the influence of different levels of SA and pre-cold treatment in the dormancy period of saffron and their effects on content enzyme activity. The results indicated that the SA2%, SA1%, and, pre-cold treatments took the shortest day to flowering. PAL enzyme activity was highest in pre-cold treatment. The higher total amount of protein was measured in the control, SA1% and SA2%. The highest amount of starch content and total soluble sugar was detected in pre-cold, SA2%, and control, respectively. No significant differences between treatments were present for CAT, PPO, GPX, and APX enzymes activity. There was a negative significant correlation between flowering time and some studied traits, i.e., starch and PAL activity. Applying SA and pre-cold treatment can induce saffron flowering and effect on pal enzyme activity and corm total protein, sugar, and starch content accordingly.

Insight into the regulatory networks underlying the high lipid perennial ryegrass growth under different irradiances

Under favourable conditions, perennial ryegrass (Lolium perenne) engineered to accumulated high lipid (HL) carbon sink in their leaves was previously shown to also enhance photosynthesis and growth. The greater aboveground biomass was found to be diminished in a dense canopy compared to spaced pots. Besides, the underlying genetic regulatory network linking between leaf lipid sinks and these physiological changes remains unknown. In this study, we demonstrated that the growth advantage was not displayed in HL Lolium grown in spaced pots under low lights. Under standard lights, analysis of differentiating transcripts in HL Lolium reveals that the plants had elevated transcripts involved in lipid metabolism, light capturing, photosynthesis, and sugar signalling while reduced expression of genes participating in sugar biosynthesis and transportation. The plants also had altered several transcripts involved in mitochondrial oxidative respiration and redox potential. Many of the above upregulated or downregulated transcript levels were found to be complemented by growing the plants under low light. Overall, this study emphasizes the importance of carbon and energy homeostatic regulatory mechanisms to overall productivity of the HL Lolium through photosynthesis, most of which are significantly impacted by low irradiances.

Comparative transcriptome and metabolome analyses identified the mode of sucrose degradation as a metabolic marker for early vegetative propagation in bulbs of Lycoris

Vegetative propagation (VP) is an important practice for production in many horticultural plants. Sugar supply constitutes the basis of VP in bulb flowers, but the underlying molecular basis remains elusive. By performing a combined sequencing technologies coupled with ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry approach for metabolic analyses, we compared two Lycoris species with contrasting regeneration rates: high-regeneration Lycoris sprengeri and low-regeneration Lycoris aurea. A comprehensive multi-omics analyses identified both expected processes involving carbohydrate metabolism and transcription factor networks, as well as the metabolic characteristics for each developmental stage. A higher abundance of the differentially expressed genes including those encoding ethylene responsive factors was detected at bulblet initiation stage compared to the late stage of bulblet development. High hexose-to-sucrose ratio correlated to bulblet formation across all the species examined, indicating its role in the VP process in Lycoris bulb. Importantly, a clear difference between cell wall invertase (CWIN)-catalyzed sucrose unloading in high-regeneration species and the sucrose synthase-catalyzed pathway in low-regeneration species was observed at the bulblet initiation stage, which was supported by findings from carboxyfluorescein tracing and quantitative real-time PCR analyses. Collectively, the findings indicate a sugar-mediated model of the regulation of VP in which high CWIN expression or activity may promote bulblet initiation via enhancing apoplasmic unloading of sucrose or sugar signals, whereas the subsequent high ratio of hexose-to-sucrose likely supports cell division characterized in the next phase of bulblet formation.

Plant hormone signals regulate trehalose accumulation against osmotic stress in watermelon cells

Trehalose, one of the most chemically stable sugars, can effectively improve the tolerance of various plants against abiotic stress by protecting and stabilizing protein and cell membranes. However, the signaling pathway in trehalose biosynthesis triggered by abiotic stresses is still unclear. In the study, it can be shown that exogenous trehalose can alleviate the inhibitory effect of osmotic stress on cell growth, suppress extracellular alkalization, ROS burst, and maintain the integrity of the microtubular cytoskeleton. Trehalose-6-phosphate synthase (TPS) is the key limiting enzyme for trehalose synthesis and is encoded by 7 ClTPS genes, located in 7 different chromosomes of the watermelon genome. Expression analysis by qRT-PCR indicated that osmotic stress could upregulate the expression of all the family members of ClTPS and promote the accumulation of trehalose in watermelon cells accordingly. Exogenous methyl jasmonate (MeJA), ethephon (ETH), abscisic acid (ABA), or salicylic acid (SA) induced trehalose accumulation, with MeJA being the most effective treatment. When fluridone (FL), an ABA biosynthesis inhibitor, was pre-perfused into the cells before osmotic stress, trehalose accumulation and packed cell volume were suppressed significantly, whereas inhibition of ethylene biosynthesis could even restore cell growth. Moreover, inhibition of trehalose hydrolysis could also increase the tolerance against osmotic stress. This study shows that trehalose biosynthesis is phytohormone-dependent and the hydrolysis of trehalose is involved in osmotic tolerance regulation.

Foliar application of ethephon induces bud dormancy and affects gene expression of dormancy- and flowering-related genes in 'Mauritius' litchi (Litchi chinensis Sonn.)

A previous study showed that foliar application of ethephon to litchi trees with mature shoots and dormant terminal buds during autumn successfully inhibited new vegetative shoot growth prior to floral induction thereby promoting carbohydrate accumulation and flowering. However, the functional mechanisms of ethylene, the breakdown product of ethephon, in the leaves and terminal buds of litchi and its involvement in the flowering process is largely unknown. Therefore, this study aimed to investigate the phenological, physiological and molecular changes underlying ethephon application and its associations with bud dormancy and flowering in litchi. Ethephon was applied as a single full canopy spray at a concentration of 1000 mg⋅L^-1 to 'Mauritius' litchi trees with mature vegetative shoots and dormant terminal buds during late autumn of 2018 (mid-April; Southern Hemisphere). Untreated trees served as a control. Phenological characteristics, such as bud dormancy and panicle development, leaf chlorophyll (as an indicator of shoot maturity), ethylene evolution, gene expression levels of flowering- (LcFT2, LcFLC and LcAP1), dormancy- (LcSVP1 and LcSVP2) and ethylene pathway-related (LcEIN3) genes and non-structural carbohydrates were determined in terminal buds, leaves and/or shoots. Ethephon application induced bud dormancy, significantly delayed panicle emergence and promoted pure floral panicle development under more favorable inductive conditions. Ethylene evolution increased sharply 2 h after application in both leaves and terminal buds, but decreased rapidly thereafter in the leaves, while remaining high in terminal buds for seven days before gradually declining. Ethephon application significantly increased relative expression of LcEIN3 and LcFLC in terminal buds one day after application, while LcFT2 expression in leaves and LcAP1 expression in terminal buds were significantly increased at the bud break stage. Significant treatments differences were also observed for various carbohydrate metabolites in leaves and shoots at the bud break or floral initiation stage. Our study provided evidence that ethephon application plays an important role in the physiological and molecular regulation of bud dormancy of litchi. By influencing the time of bud break, ethephon application can be a useful tool to manage panicle emergence under less inductive conditions.

Phytochemical Classification of Medicinal Plants Used in the Treatment of Kidney Disease Based on Traditional Persian Medicine

Methods

This review was focused on studying the various secondary metabolites in model plants of Iranian herbal medicine known as treatment of kidney diseases in traditional Persian medicine textbooks including Makhzan-ol-Advieh, The Canon of Medicine, and Taghvim al-Abdan fi Tadbir al-Ensan.

Results

Secondary metabolites of 94 medical plants belonging to 42 families were reported with their scientific and family name.

Conclusion

Although herbal medicines are gaining rapid popularity among people and the pharmaceutical industry, the understandings of the phytochemical and therapeutic properties of medicinal plant are important for developing effective nephroprotective medicines. Therefore, the relationship between traditional uses and biological properties should be clearly verified through further studies.

Source-To-Sink Transport of Sugar and Its Role in Male Reproductive Development

Sucrose is produced in leaf mesophyll cells via photosynthesis and exported to non-photosynthetic sink tissues through the phloem. The molecular basis of source-to-sink long-distance transport in cereal crop plants is of importance due to its direct influence on grain yield-pollen grains, essential for male fertility, are filled with sugary starch, and rely on long-distance sugar transport from source leaves. Here, we overview sugar partitioning via phloem transport in rice, especially where relevant for male reproductive development. Phloem loading and unloading in source leaves and sink tissues uses a combination of the symplastic, apoplastic, and/or polymer trapping pathways. The symplastic and polymer trapping pathways are passive processes, correlated with source activity and sugar gradients. In contrast, apoplastic phloem loading/unloading involves active processes and several proteins, including SUcrose Transporters (SUTs), Sugars Will Eventually be Exported Transporters (SWEETs), Invertases (INVs), and MonoSaccharide Transporters (MSTs). Numerous transcription factors combine to create a complex network, such as DNA binding with One Finger 11 (DOF11), Carbon Starved Anther (CSA), and CSA2, which regulates sugar metabolism in normal male reproductive development and in response to changes in environmental signals, such as photoperiod.

Functional characterization and analysis of transcriptional regulation of sugar transporter SWEET13c in sugarcane Saccharum spontaneum

BACKGROUND

Sugarcane is an important crop for sugar production worldwide. The Sugars Will Eventually be Exported Transporters (SWEETs) are a group of sugar transporters recently identified in sugarcane. In Saccharum spontaneum, SsSWEET13c played a role in the sucrose transportation from the source to the sink tissues, which was found to be mainly active in the mature leaf. However, the function and regulation of SWEETs in sugarcane remain elusive despite extensive studies performed on sugar metabolism.

RESULTS

In this study, we showed that SsSWEET13c is a member of SWEET gene family in S. spontaneum, constituting highest circadian rhythm-dependent expression. It is a functional gene that facilitates plant root elongation and increase fresh weight of Arabidopsis thaliana, when overexpressed. Furthermore, yeast one-hybrid assays indicate that 20 potential transcription factors (TFs) could bind to the SsSWEET13c promoter in S. spontaneum. We combined transcriptome data from developmental gradient leaf with distinct times during circadian cycles and stems/leaves at different growth stages. We have uncovered that 14 out of 20 TFs exhibited positive/negative gene expression patterns relative to SsSWEET13c. In the source tissues, SsSWEET13c was mainly positively regulated by SsbHLH34, SsTFIIIA-a, SsMYR2, SsRAP2.4 and SsbHLH035, while negatively regulated by SsABS5, SsTFIIIA-b and SsERF4. During the circadian rhythm, it was noticed that SsSWEET13c was more active in the morning than in the afternoon. It was likely due to the high level of sugar accumulation at night, which was negatively regulated by SsbZIP44, and positively regulated by SsbHLH34. Furthermore, in the sink tissues, SsSWEET13c was also active for sugar accumulation, which was positively regulated by SsbZIP44, SsTFIIIA-b, SsbHLH34 and SsTFIIIA-a, and negatively regulated by SsERF4, SsHB36, SsDEL1 and SsABS5. Our results were further supported by one-to-one yeast hybridization assay which verified that 12 potential TFs could bind to the promoter of SsSWEET13c.

CONCLUSIONS

A module of the regulatory network was proposed for the SsSWEET13c in the developmental gradient of leaf and circadian rhythm in S. spontaneum. These results provide a novel understanding of the function and regulation of SWEET13c during the sugar transport and biomass production in S. spontaneum.

Metabolomics Analysis Provides New Insights Into the Molecular Mechanisms of Parasitic Plant Dodder Elongation in vitro

Dodder (Cuscuta spp.) species are obligate parasitic flowering plants that totally depend on host plants for growth and reproduction and severely suppress hosts' growth. As a rootless and leafless plant, excised dodder shoots exhibit rapid growth and elongation for several days to hunt for new host stems, and parasitization could be reestablished. This is one unique ability of the dodder to facilitate its success in nature. Clearly, excised dodder stems have to recycle stored nutrients to elongate as much as possible. However, the mechanism of stored nutrient recycling in the in vitro dodder shoots is still poorly understood. Here, we found that dodder is a carbohydrate-rich holoparasitic plant. During the in vitro dodder shoot development, starch was dramatically and thoroughly degraded in the dodder shoots. Sucrose derived from starch degradation in the basal stems was transported to the shoot tips, in which EMP and TCA pathways were activated to compensate for carbon demand for the following elongation according to the variations of sugar content related to the crucial gene expression, and the metabolomics analysis. Additionally, antioxidants were significantly accumulated in the shoot tips in contrast to those in the basal stems. The variations of phytohormones (jasmonic acid, indole-3-acetic acid, and abscisic acid) indicated that they played essential roles in this process. All these data suggested that starch and sucrose degradation, EMP and TCA activation, antioxidants, and phytohormones were crucial and associated with the in vitro dodder shoot elongation.

An overview of sucrose transporter (SUT) genes family in rice

INTRODUCTION

Photosynthesis provides the energy basis for the life activities of plants by producing organic compounds, mainly sugar. As the main energy form of photosynthesis, sugar affects the growth and development of plants. During long-distance transportation, sucrose is the main form of transportation. The rate of sugar transport and the allocation of carbohydrates affect the biomass of crops and are closely related to the reproductive growth of crops.

MAIN TEXT

The transportation of sugar is divided into active transportation and passive transportation. So how does the sucrose transporters (SUT) genes, which are the main carriers of sucrose in active transportation, affect the performance of rice agronomic traits is still to be explored. In this article, we describe the structure of inflorescence and review the transport forms and metabolic processes of sucrose in rice, such as how CO₂ is fixed, carbohydrate assimilation, and transport of organic matter. Sucrose transporters exhibited remarkable effects on the development of reproductive organs in rice.

CONCLUSIONS

Here, the effects of different factors, such as the effects of anthers morphology on starch enrichment of pollen, effects of biotic and abiotic factors on sucrose transporters, effects of changes in trace elements on sucrose transporters, were discussed. Moreover, the regulation of transcription or translation level provides ideas for future research on sucrose transporters.

Glucose Supply Induces PsMYB2-Mediated Anthocyanin Accumulation in Paeonia suffruticosa 'Tai Yang' Cut Flower

Tree peony (Paeonia suffruticosa) is a well-known Chinese ornamental plant with showy flower color. However, the color fading problem during vase time seriously blocks its development in the cut flower market. In this study, we found that exogenous glucose supply improved the color quality of P. suffruticosa 'Tai Yang' cut flowers with increased total soluble sugar and anthocyanin contents of petals. Besides, the promotion effect of glucose was better than the osmotic control of 3-O-methylglucose (3OMG) treatment and the glucose analog mannose treatment. The structural genes, including PsF3H, PsF3'H, PsDFR, PsAOMT, and PsUF5GT, were remarkably upregulated under glucose treatment. Meanwhile, the regulatory genes, including PsbHLH1, PsbHLH3, PsMYB2, PsWD40-1, and PsWD40-2, also showed a strong response to glucose treatment. Among these five regulatory genes, PsMYB2 showed less response to 3OMG treatment but was highly expressed under glucose and mannose treatments, indicating that PsMYB2 may have an important role in the glucose signal pathway. Ectopic overexpression of PsMYB2 in Nicotiana tabacum resulted in a strong pigmentation in petals and stamens of tobacco flowers accompanied with multiple anthocyanin biosynthetic genes upregulated. More importantly, the overexpression of PsMYB2 enhanced the ability of glucose-induced anthocyanin accumulation in Arabidopsis thaliana seedlings since PsMYB2-overexpressing Arabidopsis showed higher expression levels of AtPAL1, AtCHS, AtF3H, AtF3'H, AtDFR, and AtLDOX than those of wild type under glucose treatment. In summary, we suggested that glucose supply promoted petal coloration of P. suffruticosa 'Tai Yang' cut flower through the signal pathway, and PsMYB2 was a key component in this process. Our research made a further understanding of the mechanism that glucose-induced anthocyanin biosynthesis of P. suffruticosa cut flowers during postharvest development, laying a foundation for color retention technology development of cut flowers.

First Discovery of Novel Cytosine Derivatives Containing a Sulfonamide Moiety as Potential Antiviral Agents

A series of cytosine derivatives containing a sulfonamide moiety were designed and synthesized, and their antiviral activities against pepper mild mottle virus (PMMoV) were systematically evaluated. Then, a three-dimensional quantitative structure-activity relationship (3D-QSAR) model was constructed to study the structure-activity relationship according to the pEC₅₀ of the compounds' protective activities. Next, compound A32 with preferable antiviral activity on PMMoV was obtained based on the CoMSIA and CoMFA models, with an EC₅₀ of 19.5 μg/mL, which was superior to the template molecule A25 (21.3 μg/mL) and ningnanmycin (214.0 μg/mL). In addition, further studies showed that the antiviral activity of compound A32 against PMMoV was in accord with the up-regulation of proteins expressed in the defense response and carbon fixation in photosynthetic organisms. These results indicated that cytosine derivatives containing a sulfonamide moiety could be used as novel potential antiviral agents for further research and development.