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Seed germination plays important roles in the establishment of seedlings and their subsequent growth; however, seed germination is inhibited by salinity, and the inhibitory mechanism remains elusive. Our results indicate that NaCl treatment inhibits rice seed germination by decreasing the contents of bioactive gibberellins (GAs), such as GA and GA and that this inhibition can be rescued by exogenous bioactive GA application. To explore the mechanism of bioactive GA deficiency, the effect of NaCl on GA metabolic gene expression was investigated, revealing that expression of both GA biosynthetic genes and GA-inactivated genes was up-regulated by NaCl treatment. These results suggest that NaCl-induced bioactive GA deficiency is caused by up-regulated expression of GA-inactivated genes, and the up-regulated expression of GA biosynthetic genes might be a consequence of negative feedback regulation of the bioactive GA deficiency. Moreover, we provide evidence that NaCl-induced bioactive GA deficiency inhibits rice seed germination by decreasing α-amylase activity via down-regulation of α-amylase gene expression. Additionally, exogenous bioactive GA rescues NaCl-inhibited seed germination by enhancing α-amylase activity. Thus, NaCl treatment reduces bioactive GA content through promotion of bioactive GA inactivation, which in turn inhibits rice seed germination by decreasing α-amylase activity via down-regulation of α-amylase gene expression.

The α-amylase is a ubiquitous starch hydrolase catalyzing the cleavage of the α-1,4-glucosidic bonds in an endo-fashion. Various α-amylases originating from different taxonomic sources may differ from each other significantly in their exact substrate preference and product profile. Moreover, it also seems to be clear that at least two different amino acid sequences utilizing two different catalytic machineries have evolved to execute the same α-amylolytic specificity. The two have been classified in the Cabohydrate-Active enZyme database, the CAZy, in the glycoside hydrolase (GH) families GH13 and GH57. While the former and the larger α-amylase family GH13 evidently forms the clan GH-H with the families GH70 and GH77, the latter and the smaller α-amylase family GH57 has only been predicted to maybe define a future clan with the family GH119. Sequences and several tens of enzyme specificities found throughout all three kingdoms in many taxa provide an interesting material for evolutionarily oriented studies that have demonstrated remarkable observations. This review emphasizes just the three of them: (1) a close relatedness between the plant and archaeal α-amylases from the family GH13; (2) a common ancestry in the family GH13 of animal heavy chains of heteromeric amino acid transporter rBAT and 4F2 with the microbial α-glucosidases; and (3) the unique sequence features in the primary structures of amylomaltases from the genus Borrelia from the family GH77. Although the three examples cannot represent an exhaustive list of exceptional topics worth to be interested in, they may demonstrate the importance these enzymes possess in the overall scientific context.

Societal Impact Statement Apples are affordable and accessible fruit with tremendous biodiversity. Among over 10,000 identified apple cultivars, only a few are commercially available. Habitual fruit consumption is correlated with the prevention of Type 2 diabetes and related complications. Particularly, (poly)phenols found in apples are major contributors to their antidiabetic properties. Here, we have screened (poly)phenol‐rich extracts of 476 apple accessions in Canada's Apple Biodiversity Collection for antidiabetic properties. The results of this work provide insights into the prevention and management of Type 2 diabetes by identifying high (poly)phenol‐containing specialty apples for use in fresh fruit form or value‐added functional food ingredients. Summary The recent trend in sedentary lifestyles and nutritionally‐imbalanced diets has elevated the prevalence of Type 2 diabetes in many parts of the world. Some pharmacological glycemic management can cause undesirable gastrointestinal side effects or hypoglycemia. Thus, there is a growing interest in safe glycemic management using dietary (poly)phenols. In this study, (poly)phenol‐rich extracts of 476 apple accessions from Canada's Apple Biodiversity Collection (ABC) and six major apple (poly)phenols were assessed for in vitro antidiabetic properties against the activities of α‐glucosidase, α‐amylase, and dipeptidyl peptidase‐4 (DPP‐4) and the formation of advanced glycation end products (AGE). Apple (poly)phenol extracts varied in their antidiabetic activities in a dose‐dependent manner. High (poly)phenol‐containing apples demonstrated that their total phenolic contents (TPC) were inversely correlated with the IC50 values of α‐glucosidase, α‐amylase, and AGE formation, but not DPP‐4. Concentrations of major (poly)phenol compounds such as procyanidin B2, phloridzin, and epicatechin in apples were significantly inversely correlated with IC50 values of α‐glucosidase in the high (poly)phenol‐containing apples. High TPC apples are not suitable for marketing for fresh fruit consumption due to bitterness and astringency; however, these apples show potential to use in the development of value‐added functional food ingredients or nutraceuticals for blood glucose management. The high TPC apple, “S23‐03‐749,” an advanced breeding line of dessert apple, presents a novel option as a specialty apple cultivar for the dietary management of glycemia. Summary Les pommes sont des fruits abordables et accessibles avec une formidable biodiversité. Parmi plus de 10,000 cultivars de pommiers identifiés, seuls quelques‐uns sont disponibles dans le commerce. La consommation habituelle de fruits est corrélée à la prévention du diabète de type 2 et des complications associées. En particulier, les (poly)phénols présents dans les pommes sont des contributeurs majeurs à leurs propriétés antidiabétiques. Ici, nous avons examiné des extraits riches en (poly)phénols de 476 pommes de la Collection Biodiversité des pommes du Canada pour leurs propriétés antidiabétiques. Les résultats de ces travaux donnent un aperçu de la prévention et de la gestion du diabète de type 2 en identifiant des pommes de spécialité à haute teneur en (poly)phénols à utiliser sous forme de fruits frais ou d'ingrédients alimentaires fonctionnels à valeur ajoutée. Apples are affordable and accessible fruit with tremendous biodiversity. Among over 10,000 identified apple cultivars, only a few are commercially available. Habitual fruit consumption is correlated with the prevention of Type 2 diabetes and related complications. Particularly, (poly)phenols found in apples are major contributors to their antidiabetic properties. Here, we have screened (poly)phenol‐rich extracts of 476 apple accessions in Canada's Apple Biodiversity Collection for antidiabetic properties. The results of this work provide insights into the prevention and management of Type 2 diabetes by identifying high (poly)phenol‐containing specialty apples for use in fresh fruit form or value‐added functional food ingredients.

α-Amylases (E.C 3.2.1.1) hydrolyse starch into smaller moieties such as maltose and glucose by breaking α-1,4-glycosidic linkages. The application of α-amylases in various industries has made the large-scale productions of these enzymes crucial. Thermostable α-amylase that catalyses starch degradation at the temperatures higher than 50 °C is favourable in harsh industrial applications. Due to ease in genetic manipulation and bulk production, this enzyme is most preferably produced by microorganisms. Bacillus sp. and Escherichia coli are commonly used microbial expression hosts for α-amylases (30 to 205 kDa in molecular weight). These amylases can be purified using ultrafiltration, salt precipitation, dialysis, and column chromatography. Recently, affinity column chromatography has shown the most promising result where the recovery rate was 38 to 60% and purification up to 13.2-fold. Microbial thermostable α-amylases have the optimum temperature and pH ranging from 50 °C to 100 °C and 5.0 to 10.5, respectively. These enzymes have high specificity towards potato starch, wheat starch, amylose, and amylopectin. EDTA (1 mM) gave the highest inhibitory effect (79%), but Ca2+ (5 mM) was the most effective co-factor with 155%. This review provides insight regarding thermostable α-amylases obtained from microbial sources for industrial applications.

Amylase is an indispensable hydrolase in insect growth and development. Its varied enzymatic parameters cause insects to have strong stress resistance. Amylase gene replication is a very common phenomenon in insects, and different copies of amylase genes enable changes in its location and function. In addition, the classification, structure, and interaction between insect amylase inhibitors and amylases have also invoked the attention of researchers. Some plant-derived amylase inhibitors have inhibitory activities against insect amylases and even mammalian amylases. In recent years, an increasing number of studies have clarified the effects of pesticides on the amylase activity of target and non-target pests, which provides a theoretical basis for exploring safe and efficient pesticides, while the exact lethal mechanisms and safety in field applications remain unclear. Here, we summarize the most recent advances in insect amylase studies, including its sequence and characteristics and the regulation of amylase inhibitors (α-AIs). Importantly, the application of amylases as the nanocide trigger, RNAi, or other kinds of pesticide targets will be discussed. A comprehensive foundation will be provided for applying insect amylases to the development of new-generation insect management tools and improving the specificity, stability, and safety of pesticides.

The concept of functional foods is gaining more importance due to its role in maintaining a healthy status and preventing some metabolic diseases. The control of diabetes, in particular type-2 (T2DM), could be considered a big challenge since it involves other factors such as eating habits. From the pharmacological point of view, inhibiting digestive enzymes, such as α-amylase and α-glucosidase, is one of the mechanisms mainly used by synthetic drugs to control this disease; however, several side effects are described. For that reason, using bioactive compounds may appear as an alternative without presenting the complications synthetic drugs available on the market have. The winemaking industry generates tons of waste annually, and grape pomace (GP) is the most important. GP is recognized for its nutritional value and as a source of bioactive compounds that are helpful for human health. This review highlights the importance of GP as a possible source of α-amylase and α-glucosidase inhibitors. Also, it is emphasized the components involved in this bioactivity and the possible interactions among them. Especially, some phenolic compounds and fiber of GP are the main ones responsible for interfering with the human digestive enzymes. Preliminary studies in vitro confirmed this bioactivity; however, further information is required to allow the specific use of GP as a functional ingredient inside the market of products recommended for people with diabetes. Graphical abstract

genus of Asteraceae family is a source of medicinal plants known worldwide and used as ethnopharmacological remedies for the treatment of diabetes in Northern Asia (Siberia). The aim of this study was to determine the phenolic profile of 12 Siberian species ( ) and to test the efficacy of plant extracts and pure compounds for antidiabetic potential. Finally, by HPLC-DAD-ESI-TQ-MS/MS technique, 112 individual phenolic compounds were detected in extracts in a wide range of concentrations. Some species accumulated rare plant phenolics, such as coumarin-hemiterpene ethers (lacarol derivatives) from and ; melilotoside from ; dihydrochalcones (davidigenin analogs) from ; chrysoeriol glucosides from , and ; eriodictyol glycosides from ; and some uncommon flavones and flavonols. The predominant phenolic group from species herb was caffeoylquinic acid (CQAs), and in all species, the major CQAs were 5- -CQA (20.28-127.99 μg/g) and 3,5-di- -CQA (7.35-243.61 μg/g). In a series of bioassays, all studied extracts showed inhibitory activity against principal enzymes of carbohydrate metabolism, such as α-amylase (IC = 150.24-384.14 μg/mL) and α-glucosidase (IC = 214.42-754.12 μg/mL). Although many phenolic compounds can be inhibitors, experimental evidence suggests that the CQAs were key to the biological response of extracts. Mono-, di- and tri-substituted CQAs were assayed and showed inhibition of α-amylase and α-glucosidase, with IC values of 40.57-172.47 μM and 61.08-1240.35 μM, respectively, and they were more effective than acarbose, a well-known enzyme inhibitor. The results obtained in this study reveal that Siberian species and CQAs possess a pronounced inhibitory activity against α-amylase and α-glucosidase and could become a complement to synthetic antidiabetic drugs for controlling blood glucose level.

α-Amylase is a generally acknowledged molecular target of a distinct class of antidiabetic drugs named α-glucosidase inhibitors. This class of medications is scarce and rather underutilized, and treatment with current commercial drugs is accompanied by unpleasant adverse effects. However, mammalian α-amylase inhibitors are abundant in nature and form an extensive pool of high-affinity ligands that are available for drug discovery. Individual compounds and natural extracts and preparations are promising therapeutic agents for conditions associated with impaired starch metabolism, e.g., diabetes mellitus, obesity, and other metabolic disorders. This review focuses on the structural diversity and action mechanisms of active natural products with inhibitory activity toward mammalian α-amylases, and emphasizes proteinaceous inhibitors as more effective compounds with significant potential for clinical use.

This study brings a detailed bioinformatics analysis of fungal and chloride-dependent α-amylases from the family GH13. Overall, 268 α-amylase sequences were retrieved from subfamilies GH13_1 (39 sequences), GH13_5 (35 sequences), GH13_15 (28 sequences), GH13_24 (23 sequences), GH13_32 (140 sequences) and GH13_42 (3 sequences). Eight conserved sequence regions (CSRs) characteristic for the family GH13 were identified in all sequences and respective sequence logos were analysed in an effort to identify unique sequence features of each subfamily. The main emphasis was given on the subfamily GH13_32 since it contains both fungal α-amylases and their bacterial chloride-activated counterparts. In addition to in silico analysis focused on eventual ability to bind the chloride anion, the property typical mainly for animal α-amylases from subfamilies GH13_15 and GH13_24, attention has been paid also to the potential presence of the so-called secondary surface-binding sites (SBSs) identified in complexed crystal structures of some particular α-amylases from the studied subfamilies. As template enzymes with already experimentally determined SBSs, the α-amylases from Aspergillus niger (GH13_1), Bacillus halmapalus, Bacillus paralicheniformis and Halothermothrix orenii (all from GH13_5) and Homo sapiens (saliva; GH13_24) were used. Evolutionary relationships between GH13 fungal and chloride-dependent α-amylases were demonstrated by two evolutionary trees—one based on the alignment of the segment of sequences spanning almost the entire catalytic TIM-barrel domain and the other one based on the alignment of eight extracted CSRs. Although both trees demonstrated similar results in terms of a closer evolutionary relatedness of subfamilies GH13_1 with GH13_42 including in a wider sense also the subfamily GH13_5 as well as for subfamilies GH13_32, GH13_15 and GH13_24, some subtle differences in clustering of particular α-amylases may nevertheless be observed.

Background Salinity is a big threat to agriculture by limiting crop production. Nanopriming (seed priming with nanomaterials) is an emerged approach to improve plant stress tolerance; however, our knowledge about the underlying mechanisms is limited. Results Herein, we used cerium oxide nanoparticles (nanoceria) to prime rapeseeds and investigated the possible mechanisms behind nanoceria improved rapeseed salt tolerance. We synthesized and characterized polyacrylic acid coated nanoceria (PNC, 8.5 ± 0.2 nm, −43.3 ± 6.3 mV) and monitored its distribution in different tissues of the seed during the imbibition period (1, 3, 8 h priming). Our results showed that compared with the no nanoparticle control, PNC nanopriming improved germination rate (12%) and biomass (41%) in rapeseeds ( Brassica napus ) under salt stress (200 mM NaCl). During the priming hours, PNC were located mostly in the seed coat, nevertheless the intensity of PNC in cotyledon and radicle was increased alongside with the increase of priming hours. During the priming hours, the amount of the absorbed water (52%, 14%, 12% increase at 1, 3, 8 h priming, respectively) and the activities of α-amylase were significantly higher (175%, 309%, 295% increase at 1, 3, 8 h priming, respectively) in PNC treatment than the control. PNC primed rapeseeds showed significantly lower content of MDA, H 2 O 2 , and • O 2 − in both shoot and root than the control under salt stress. Also, under salt stress, PNC nanopriming enabled significantly higher K + retention (29%) and significantly lower Na + accumulation (18.5%) and Na + /K + ratio (37%) than the control. Conclusions Our results suggested that besides the more absorbed water and higher α-amylase activities, PNC nanopriming improves salt tolerance in rapeseeds through alleviating oxidative damage and maintaining Na + /K + ratio. It adds more knowledge regarding the mechanisms underlying nanopriming improved plant salt tolerance. Graphical abstract