Astragalus membranaceus(A. membranaceus), a traditional tonic, contains flavonoids as one of its main bioactive components and key indicators for quality standard detection. These compounds predominantly exist in glycosylated forms after glycosylation modification within the plant. The catalytic products of flavonoid glycosyltransferases in A. membranaceus have been reported to be mostly monoglycosides, and only AmUGT28 catalyzes luteolin to form diglycosides. In this study, we cloned a glycosyltransferase gene, AmGT90, from A. membranaceus, with an ORF length of 1 335 bp, encoding 444 amino acids, and the protein had a relative molecular mass of 50.5 kDa. Phylogenetic tree analysis indicated that AmGT90 belongs to the UGT74 family. In vitro enzymatic reaction showed that AmGT90 had broad substrate specificity and could catalyze the glycosylation of various flavonoids, including isoflavones, flavones, flavanones, and chalcones. AmGT90 not only catalyzed the formation of monoglycosides but also diglycosides. In addition, the mechanism of AmGT90 catalyzing the formation of diglycosides from luteolin was preliminarily explored. The experimental results showed that AmGT90 may preferentially recognize C4'-OH of luteolin and then recognize C7-OH to form diglycosides. This study reported a glycosyltransferase from A. membranaceus capable of converting flavonoids into monoglycosides and diglycosides. This finding not only enhances our understanding of the biosynthetic pathways of flavonoid glycosides in A. membranaceus but also introduces a new component for glycoside production through synthetic biology.
Glycosyltransferases/chemistry* ; Flavonoids/chemistry* ; Astragalus propinquus/classification* ; Phylogeny ; Glycosylation ; Plant Proteins/chemistry* ; Substrate Specificity ; Cloning, Molecular ; Amino Acid Sequence

To screen and identify a chitosanase with high stability, we cloned the chitosanase gene from Bacillus atrophaeus with a high protease yield from the barren saline-alkali soil and expressed this gene in Escherichia coli. The expressed chitosanase of B. atrophaeus (BA-CSN) was purified by nickel-affinity column chromatography. The properties including optimal temperature, optimal pH, substrate specificity, and kinetic parameters of BA-CSN were characterized. The results showed that BA-CSN had the molecular weight of 31.13 kDa, the optimal temperature of 55 ℃, the optimal pH 5.5, and good stability at temperatures below 45 ℃ and pH 4.0-9.0. BA-CSN also had good stability within 4 h of pH 3.0 and 10.0, be activated by K⁺, Na⁺, Mn²⁺, Ca²⁺, Mg²⁺, and Co²⁺, (especially by Mn²⁺), and be inhibited by Fe³⁺, Cu²⁺, and Ag⁺. BA-CSN showcased the highest relative activity in the hydrolysis of colloidal chitosan, and it had good hydrolysis ability for colloidal chitin. Under the optimal catalytic conditions, BA-CSN demonstrated the Michaelis constant K_m and maximum reaction rate V_max of 9.94 mg/mL and 26.624 μmoL/(mL·min), respectively, for colloidal chitosan. In short, BA-CSN has strong tolerance to acids and alkali, possessing broad industrial application prospects.
Bacillus/genetics* ; Hydrogen-Ion Concentration ; Escherichia coli/metabolism* ; Glycoside Hydrolases/biosynthesis* ; Substrate Specificity ; Enzyme Stability ; Chitosan/metabolism* ; Temperature ; Kinetics ; Cloning, Molecular ; Bacterial Proteins/biosynthesis* ; Recombinant Proteins/genetics*

Laccases (LACs), belonging to the multicopper oxidase family, are closely associated with various biological functions including lignin synthesis and responses to biotic and abiotic stresses in plants. However, few studies have reported the laccase genes in China rose (Rosa chinensis). Prickles cause difficulties to the management and harvest of R. chinensis and have become a trait concerned in the breeding. To investigate the expression patterns of laccase genes in roses, we cloned a laccase gene from an ancient variety R. chinensis 'Old Blush' and named it RcLAC15. The expression level of RcLAC15 in prickles was significantly higher than those in roots, stems, and leaves. Fifty-eight laccase genes were identified in the genome of R. chinensis, and bioinformatics analysis revealed that RcLAC15 was a homolog of AtLAC15, predicting that RcLAC15 was a stable hydrophilic protein without transmembrane structures. The recombinant expression vector pBI121-proRcLAC15:: GUS was introduced into Arabidopsis, and GUS staining results showed that the RcLAC15 promoter specifically drove GUS gene expression at the edges of Arabidopsis leaves. In summary, RcLAC15 is a gene specifically expressed in the prickles of R. chinensis. This discovery provides a reference for exploring the biological functions of laccase genes in the prickles of R. chinensis.
Laccase/metabolism* ; Rosa/enzymology* ; Cloning, Molecular ; Gene Expression Regulation, Plant ; Plant Proteins/metabolism* ; Arabidopsis/metabolism* ; Plants, Genetically Modified/metabolism*

Cucumber (Cucumis sativus L.) is one of the most widely cultivated vegetables in the world. High temperature and other stress conditions can affect the growth and development of this plant, even leading to the decreases in yield and quality. The mitogen-activated protein kinase (MAPK) family plays a crucial role in plant stress responses. However, the role of MPK4 in the stress response of cucumber remains to be reported. In this study, we cloned CsMPK4, which encoded 383 amino acid residues. The qRT-PCR results showed that the expression level of CsMPK4 was the highest in leaves and flowers, moderate in roots, and the lowest in stems and tendrils. CsMPK4 was located in the nucleus and cytoplasm, and it had a close relationship with CmMPK4 in muskmelon. The cucumber plants overexpressing CsMPK4 became stronger and shorter, with reduced length and quantity of tendrils. Moreover, the transgenic seedlings were more resistant to high temperatures, with decreased malondialdehyde (MDA) content and increased activities of peroxidase (POD) and superoxide dismutase (SOD) in young leaves. Furthermore, the protein-protein interaction between CsMPK4 and CsVQ10, a member of the valine-glutamine family, was confirmed by yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays. The results suggested that CsVQ10 cooperated with CsMPK4 in response to the high temperature stress in cucumber. This study laid a foundation for the further study on the stress response mechanism of CsMPK4 and the breeding of stress-resistant cucumber varieties.
Cucumis sativus/metabolism* ; Mitogen-Activated Protein Kinases/physiology* ; Plant Proteins/metabolism* ; Plants, Genetically Modified/metabolism* ; Gene Expression Regulation, Plant ; Stress, Physiological/genetics* ; Cloning, Molecular

Narrow leaf 1 (NAL1) plays an important role in plant branching, while little is known about the roles of this gene in petunias. In this study, PhNAL1b was cloned from Petunia×hybrida cv. Mitchell Diploid, with a total length of 1 767 bp, encoding a protein composed of 588 amino acid residues and containing the peptidase S64 domain. The PhNAL1b promoter region contained several elements involved in the responses to auxin, jasmonic acid, abscisic acid, and light. The expression analysis showed that PhNAL1b had the highest expression level in roots and the lowest expression level in flowers, and its transcription could be inhibited by decapitation and cytokinin. The subcellular localization analysis showed that PhNAL1b was located in the nucleus and was a nuclear protein. Virus-induced gene silencing was employed to downregulate the expression of PhNAL1b, which resulted in significant increases in branch number and plant height. The results indicated that PhNAL1b played an important role in regulating the branching of petunias. This study lays a foundation for revealing the mechanism of NAL1 in regulating branch development and provides genetic resources for plant architecture improvement.
Petunia/growth & development* ; Plant Proteins/metabolism* ; Diploidy ; Gene Expression Regulation, Plant ; Cloning, Molecular ; Promoter Regions, Genetic

Flavonoid 3-O-glucosyltransferase (3GT) is a key enzyme in the glucosidation of anthocyanins. To investigate the 3GT gene in rhododendron, we cloned an open reading frame (ORF) of 3GT gene (named Rh3GT) from Rhododendron hybridum Hort (Red cultivar) and then characterized this gene and the deduced protein in terms of the biochemical characteristics, expression level, and enzymatic function. The results showed that Rh3GT had a full length of 993 bp and encoded 330 amino acid residues. The deduced protein was hydrophilic, stable, weak acid, belonging to the glycosyltransferase family (GT-B type), with glutamine (Q) at position 44 in the PSPG box. The phylogenetic analysis showed that Rh3GT was most closely related to Vc3GT from Vaccinium corymbosum and Vm3GT from Vaccinium myrtillus. Rh3GT was expressed in the stems, leaves, and flowers and almost not expressed in the roots, with the highest expression level in petals during full blooming stage. Introduction of pCAMBIAL1302-Rh3GT into petals significantly up-regulated the expression level of Rh3GT and increased the total anthocyanin accumulation. Rh3GT was successfully expressed in Escherichia coli BL21 in the form of inclusion bodies with a size of about 36 kDa. The results of HPLC showed that the recombinant Rh3GT after denaturation, purification, and dilution could catalyze the synthesis of cyanidin and UDP-glucose to synthesize cyanidin 3-O-glucoside, indicating that the expressed protein had 3GT activity. This study provides basic data for further studying the molecular regulation mechanism of anthocyanin biosynthesis and theoretical support for molecular breeding of rhododendron.
Rhododendron/classification* ; Glucosyltransferases/metabolism* ; Cloning, Molecular ; Escherichia coli/metabolism* ; Recombinant Proteins/biosynthesis* ; Anthocyanins/biosynthesis* ; Phylogeny ; Plant Proteins/metabolism* ; Amino Acid Sequence

The plant F-box protein more axillary growth 2 (MAX2) is a key factor in the signal transduction of strigolactones (SLs) and karrinkins (KARs). As the main component of the SKP1-CUL1-FBX (SCF) complex ubiquitin ligase E3, MAX2 is responsible for specifically recognizing the target proteins, suppressor of MAX2 1/SMAX1-like proteins (SMAX1/SMXLs), which would be degraded after ubiquitination. It can thereby regulate plant morphogenesis and stress responses. There exist homologous genes of MAX2 in the important grain and oil crop soybean (Glycine max). However, its role in plant defense responses has not been investigated yet. Here, GmMAX2b, a homologous gene of MAX2, was successfully cloned from stressed soybean. Bioinformatics analysis revealed that there were two MAX2 homologous genes, GmMAX2a and GmMAX2b, with a similarity of 96.2% in soybean. Their F-box regions were highly conserved. The sequence alignment and cluster analysis of plant MAX2 homologous proteins basically reflected the evolutionary relationship of plants and also suggested that soybean MAX2 might be a multifunctional protein. Expression analysis showed that plant pathogen infection and salicylic acid treatment induced the expression of GmMAX2b in soybean, which is consistent with that of MAX2 in Arabidopsis. Ectopic expression of GmMAX2b compensated for the susceptibility of Arabidopsis max2-2 mutant to pathogen, indicating that GmMAX2b positively regulated plant disease resistance. In addition, yeast two hybrid technology was used to explore the potential target proteins of GmMAX2b. The results showed that GmMAX2b interacted with SMXL6 and weakly interacted with SMXL2. In summary, GmMAX2b is a positive regulator in plant defense responses, and its expression is induced by pathogen infection and salicylic acid treatment. GmMAX2b might exert its effect through interaction with SMXL6 and SMXL2. This study expands the theoretical exploration of soybean disease resistant F-box and provides a scientific basis for future soybean disease resistant breeding.
Glycine max/metabolism* ; Disease Resistance/genetics* ; Plant Diseases/immunology* ; Plant Proteins/genetics* ; Cloning, Molecular ; Gene Expression Regulation, Plant ; F-Box Proteins/genetics* ; Arabidopsis/genetics* ; Phylogeny

Anthoceros angustus Steph. is rich in phenolic acids such as rosmarinic acid (RA). Phenylalanine ammonia-lyase (PAL) is an entry enzyme in the phenylpropanoid pathway of plants, playing an important role in the biosynthesis of RA. To investigate the important role of PAL in rosmarinic acid synthesis, two PAL genes (designated as AanPAL1 and AanPAL2) were cloned from A. angustus, encoding 755 and 753 amino acid residues, respectively. The AanPAL deduced amino acid sequences contain the conserved domains of PAL and the core active amino acid residues Ala-Ser-Gly. The phylogenetic analysis indicated that AanPAL1 and AanPAL2 were clustered with PALs from bryophytes and ferns and had the shortest evolutionary distance with the PALs from Physcomitrella patens. Quantitative real-time PCR results showed that the expression of AanPAL1 and AanPAL2 was induced by exogenous methyl jasmonate (MeJA). HPLC results showed that the MeJA treatment significantly increased the accumulation of RA. AanPAL1 and AanPAL2 were expressed in Escherichia coli and purified by histidine-tag affinity chromatography. The recombinant proteins catalyzed the conversion of L-phenylalanine to generate trans-cinnamic acid with high efficiency, with the best performance at 50 ℃ and pH 8.0. The K_m and k_cat of AanPAL1 were 0.062 mmol/L and 4.35 s^-1, and those of AanPAL2 were 0.198 mmol/L and 14.48 s^-1, respectively. The specific activities of AanPAL1 and AanPAL2 were 2.61 U/mg and 8.76 U/mg, respectively. The two enzymes had relatively poor thermostability but good pH stability. The high activity of AanPAL2 was further confirmed via whole-cell catalysis with recombinant E. coli, which could convert 1 g/L L-phenylalanine into trans-cinnamic acid with a yield of 100% within 10 h. These results give insights into the regulatory role of AanPAL in the biosynthesis of RA in A. angustus and provide candidate enzymes for the biosynthesis of cinnamic acid.
Phenylalanine Ammonia-Lyase/metabolism* ; Cloning, Molecular ; Cinnamates/metabolism* ; Recombinant Proteins/metabolism* ; Rosmarinic Acid ; Depsides/metabolism* ; Escherichia coli/metabolism* ; Amino Acid Sequence ; Plant Proteins/metabolism* ; Phylogeny ; Acetates/pharmacology* ; Cyclopentanes ; Oxylipins

Rice (Oryza sativa L.) is an important food crop. The appearance of lesion mimics in rice leads to phytohormone disorders, which affects rice adaptation to environmental stresses and ultimately reduces the yield and quality. To explore whether the changes in the adaptability of rice lesion-mimic mutants to stressful environments are caused by the disorder of phytohormone metabolism in plants. In this study, we screened an ethyl methane sulfonate-treated population of the japonica cultivar 'Taipei 309' for a mutant with rust-like spots on leaves at the early tillering stage and brown-red spots at maturity and named it rsl1 (rust spotted leaf 1). Compared with the wild type, rsl1 showed decreases in plant height, panicle length, primary branch number, secondary branch number, filled grains per panicle, seed-setting rate, and 1 000-grain weight, and an increase in number of effective panicles. Genetic analysis indicated that rsl1 was controlled by a single recessive nuclear gene. RSL1 was localized between two molecular markers, B7-7 and B7-9, on rice chromosome 7 by map-based cloning. PCR sequencing of the annotated genes in this interval revealed a mutation of C1683A on the eighth exon of SPL5 (LOC_Os07g10390) in rsl1, which resulted in premature termination of protein translation. Exogenous phytohormone treatments showed that rsl1 was less sensitive to salicylic acid (SA), abscisic acid (ABA), and indo-3-acetic acid (IAA) and more sensitive to methyl jasmonate (MeJA) and gibberellin acid (GA) than the wild type. In addition, the survival rate of rsl1 was lower than that of the wild type under salt, alkali, drought, and high temperature stresses, and it was higher than that of the wild type under cold stress. Quantitative real-time polymerase chain reaction (qRT-PCR) results showed that RSL1 was involved in the regulation of ABA, SA, MeJA, IAA, and GA-related genes under abiotic stresses. The present study showed that the RSL1 mutation led to the appearance of lesion mimics and affected the growth, development, and stress resistance of rsl1 under abiotic stresses. The study of the functional mechanism of this gene can provide theoretical guidance for the research on rice stress resistance.
Oryza/microbiology* ; Stress, Physiological/genetics* ; Plant Diseases/genetics* ; Cloning, Molecular ; Chromosome Mapping ; Plant Growth Regulators/metabolism* ; Plant Proteins/genetics* ; Mutation ; Cyclopentanes ; Genes, Plant ; Plant Leaves/genetics* ; Oxylipins

Bacillus coagulans can utilize the hydrolyzed carbon source of agricultural waste to produce lactic acid via a homofermentative pathway. However, a significant carbon source metabolic repression effect was observed when the strain metabolized mixed sugars (glucose and xylose), reducing the productivity of lactic acid. In this study, we obtained the fermentation conditions for the simultaneous utilization of the mixed sugars by B. coagulans by changing the ratio of glucose to xylose in the medium. Through transcriptome sequencing, several key genes responsible for xylose utilization were identified. The critical role of xylose isomerase (XylA, EC 5.3.1.5) in the synchronous utilization of glucose/xylose in B. coagulans was investigated via qRT-PCR (quantitative real-time polymerase chain reaction). Subsequently, the heterologous expression and characterization of the XylA-encoding gene (XylA) were conducted. It was determined that the gene encoded a protein composed of 440 amino acid residues. The secondary structure of the encoded protein was predominantly composed of α-helixes and random coils, while the higher structure of the protein was identified as a homotetramer. Then, XylA was cloned and expressed in Escherichia coli BL21(DE3), and the recombinant protein Bc-XlyA was obtained with a molecular weight of approximately 50 kDa. The optimal pH and temperature of Bc-XylA were 8.0 and 60 ℃, respectively, and Mn²⁺, Mg²⁺, and Co²⁺ had positive effects on the activity of Bc-XlyA. The present study provides scientific data on the molecular modification of B. coagulans, offering theoretical support for the efficient utilization of xylose in the strain.
Xylose/metabolism* ; Cloning, Molecular ; Bacillus coagulans/enzymology* ; Aldose-Ketose Isomerases/metabolism* ; Fermentation ; Bacterial Proteins/metabolism* ; Glucose/metabolism*