INTRODUCTION: Nicotinamide mononucleotide (NMN) has important biological activities such as anti-cancer, anti-aging and improving crop stress resistance, and its importance as a nutritional health product has been established. However, the content of NMN in plants is low, and the metabolic pathway of NMN degradation is poorly understood. It has been reported that 5'-nucleotidases can catalyze the dephosphorylation of NMN in saccharomyces cerevisiae. At present, 5'-nucleotidases have been isolated in plants, but whether they can catalyze the degradation of NMN remains unclear. Edible kale has high nutritional value. It is important to analyze the metabolic pathway of NMN in kale and increase the content of NMN by blocking the degradation pathway. 

RATIONALE: The degradation of NMN in plants is closely related to the NAD+ remediation synthesis (pyridine nucleotide cycle) pathway. Compared with bacteria and mammals, studies on the synthetic pathway of NAD+ remediation in plants mainly use isotope tracer method, lack specific gene and function analysis, and only a few related studies have been reported in plants. Eight 5'-nucleotidase genes were cloned from Collard cabbage, heterologous expression of them was performed by Escherichia coli expression system, and the catalytic properties of 5'-nucleotidase were investigated by enzymological means in vitro. 

RESULTS: In this study, ten 5'-nucleotidase genes were retrieved from the kale genome. Based on these sequences, eight 5'-nucleotidase candidate genes were successfully cloned from Brassica oleracea var. acephala, which laid a foundation for further revealing the degradation pathway of NMN. Phylogenetic analysis revealed that 5'-nucleotidase is conserved in plants, suggesting that it may play an important role in plant nucleotide metabolism. The catalytic properties of 5'-nucleotides in kale were investigated by using the expression system of Escherichia coli. In vitro enzymatic experiments showed that 5'-nucleotides can catalyze purine, pyrimidine and pyridine nucleotides, and have a wide range of substrate adaptability. Specifically, BolN2, BolN5-X1 and BolN6 can catalyze the dephosphorylation of NMN to the generation of NR, which proves that 5'-nucleotidase can catalyze the degradation of NMN in plants. In addition, BolN2, BolN5 and BolN6 can catalyze the hydrolysis of pyridine nucleotides NaMN, purine and pyrimidine nucleotides (including AMP, GMP, CMP and UMP). However, BolN7 and BolN8 have only weak catalytic activity against GMP. 

CONCLUSION: In conclusion, the 5'-nucleotidase gene from the HAD and SurE families of Collard Brassica oleracea var. acephala was cloned and phylogenetic analysis showed that it was conserved in plants. By constructing prokaryotic expression vector, 5'-nucleotidase was expressed and purified in Escherichia coli. The results of enzymatic reaction in vitro showed that BolN2, BolN5-X1 and BolN6 could catalyze the degradation of NMN to produce NR. In addition, BolN2, BolN5 and BolN6 have catalytic effects on NaNM, purine and pyrimidine nucleotides. This study further enhanced our understanding of the NMN metabolic pathway in kale, and provided a theoretical basis for creating edible kale with high NMN content.

INTRODUCTION: Galactinol synthase (GolS) is a key enzyme in the biosynthetic pathway of raffinose family oligosaccharides (RFOs), providing the activated galactosyl group for the biosynthesis and accumulation of RFOs in plants. It plays an important role in plant responses to abiotic stresses. 

RATIONALE: Although the role of GolS in plant stress responses has been extensively studied, little is known about the molecular characteristics of the GolS gene family (LiGolS) in Lagerstroemia indica. This study aims to identify the members of the LiGolS gene family, analyze their physicochemical properties, gene structure, and expression patterns, and explore their potential functions in salt stress response. 

RESULTS: A total of 13 LiGolS gene family members were identified at the whole-genome level and were classified into three subfamilies based on phylogenetic relationships. These genes were unevenly distributed across 10 chromosomes. The isoelectric points of the 13 LiGolS proteins ranged from 4.75 to 9.45, with molecular weights varying from 37.69 to 46.12 kDa and amino acid counts ranging from 327 to 404. Subcellular localization prediction revealed that six proteins were localized to chloroplasts, one to mitochondria, five to the cytoplasm, and one to vacuoles. Additionally, the number of exons in the 13 gene members ranged from 0 to 4. Expression analysis under salt stress showed that all LiGolS genes were upregulated to varying degrees after salt treatment, suggesting their potential involvement in salt stress response in Lagerstroemia indica. 

CONCLUSION: This study systematically identified and characterized the LiGolS gene family members in Lagerstroemia indica for the first time, including their physicochemical properties, gene structure, and expression patterns. These results lay the foundation for further functional analysis of LiGolS genes and provide theoretical insights into their roles in stress responses.

INTRODUCTION: Genetic diversity is considered as a crucial aspect in assessment and conservation of rare and endangered species. Brachystachyum densiflorum is a species endemic to eastern China. In recent years, with rapid economic development, accelerated urbanization, and escalating pollutant emissions, the habitat of B. densiflorum has been continuously degraded, habitat fragmentation has intensified, and its populations have shown a tendency to decline. 

RATIONALE: Genetic diversity endows species with abundant genetic resources and plays a pivotal role in shaping their capacity to adapt to new environments. To elucidate the genetic diversity of B. densiflorum and evaluate the influence of climate change on its genetic variation, reduced-representation genome sequencing technology was employed to obtain single nucleiotide polymorphisms (SNPs), and subsequently population genetics and landscape genetics together with species distribution modelling were analyzed. 

RESULTS: Brachystachyum densiflorum had a moderate level of genetic diversity. Six populations were divided into two groups, and there was moderate differentiation (F_ST=0.102) and high gene flow (Nm=2.442) between them. Genotype-environment association analysis indicated that the two groups were diverged attributable to local adaptation to the climate. Temperature differentials and low-temperature regimes interacting together with precipitation gave rise to genetic variation of this species. In total, 544 adaptive loci were identified, which displayed significant correlations with temperature differentials, low-temperature factors (Bio2, Bio6, Bio11, and Bio7), and precipitation factors (Bio19). B. densiflorum migrated evidently northward from the Last Glacial Maximum to the current, with its distribution area increased by 89.5%. However, during the period from 2061 to 2080, the extent of the suitable area for this species will be contracted, and there will be partial degradation and fragmentation occurring in highly suitable areas within Anhui Province. 

CONCLUSION: Brachystachyum densiflorum showed a moderate level of genetic diversity and a moderate degree of genetic differentiation. Local adaptation drove the formation of the current genetic pattern of B. densiflorum, and temperature differences, low-temperature, and precipitation led to genetic variation. B. densiflorum has evidently migrated northward from the Last Glacial Maximum to the current with increase of distribution area. However, niche modelling indicated that during the period from 2061 to 2080, the suitable habitat area of B. densiflorum would be contracted, with partial degradation and fragmentation occurring in highly suitable areas within Anhui Province. These results have significant meanings for conservation and utilization of B. densiflorum.

Identification of new loci and genes related to heat tolerance is very important for the genetic mechanism research and breeding of new heat-tolerant rice varieties. A recombinant inbred lines (RILs) was developed by crossing the japonica rice TD70 and the indica rice Kasalath. The high-density genetic linkage map with recombination Bin markers was constructed based on the re-sequencing. Based on the genotype and phenotype data of the RILs, QTL mapping of the high temperature seedling survival rate (HTSR) was performed by ICIM method of the QTL Ici Mapping software. 26 QTLs related to HTSR of rice were detected, distributed on 12 chromosomes except 3. The LOD value of single QTL ranged from 2.59–16.15, respectively. Among of them, four QTLs were detected with LOD values greater than 10. Seven QTLs were found to locate in the same interval or adjacent to known heat tolerance QTLs. Major locus qHTSR5.1 located in the 20.41-20.48 Mb of Chr. 5 with LOD value 12.07, which explained 4.86% of the total phenotypic variation for HTSR. According to the annotation and sequences analysis of genes located in the region of four major QTLs, we found that twenty-seven annotated genes with non-synonymous mutations in the coding regions between TD70 and Kasalath. The HTSR of RILs had significant difference between the RILs with different haplotype of five genes, indicating that they might be the candidate genes for HTSR. 

Plant growth regulators are natural or artificially synthesized chemical substances that play an important regulatory role in the growth and development of crops, as well as enhance the resistance of plants to stress. To study the effects of different plant growth regulators on the growth and development of wheat under salt-alkali stress, and to explore methods to increase crop yield in saline-alkaline land, we conducted spraying experiments on wheat in saline-alkaline soil in the Yellow River Delta Agricultural High-tech Industry Demonstration Zone from 2023 to 2024. The experiment was divided into four groups: a distilled water control group, a 0.5% Alginate oligosaccharide group, a Plant Gold group, and a mixed group of 0.5% Alginate oligosaccharide and Plant Gold. The wheat was sprayed on March 28, April 12, April 28, and May 12, 2024. The results showed that after spraying Alginate oligosaccharide and its mixture with Plant Gold, the number of grains per ear and the weight of 100 grains of wheat significantly increased. In particular, the group that received the mixture of Alginate oligosaccharide and Plant Gold achieved a theoretical yield of 234.9 kg per mu for wheat in saline-alkaline soil, which was an increase of 14.4% and 46.9% compared to the groups that received only Alginate oligosaccharide and Plant Gold, respectively. Therefore, the combined application of Alginate oligosaccharide and Plant Gold can significantly enhance the adaptability of wheat in saline-alkaline land, demonstrating its important application potential in wheat production in such environments.

The AT-hook motif nuclear localized (AHL) gene family is a highly conserved transcription factors involved in plant growth, development, and stress responses. To reveal the basic characteristics of AHL family in spinach, the members of the spinach SoAHL family were identified at the whole genome level, and their physicochemical properties, gene structure, conserved motifs, promoter elements, and salicylic acid-responsive expression profiles were analyzed in this study. Resulted showed that there were 19 SoAHL family members in spinach genome, which were unevenly distributed across six chromosomes. These SoAHL members can be classified into three branches, with 10 members in subfamily I and 9 members in subfamily II. Sequence composition of PPC and AT-hook conserved motifs varies among subfamilies; most of the SoAHL genes were located in nucleus, cytoplasm, and mitochondrion. Members of subfamilies I of SoAHL have no introns, while members of subfamily II contain 4–5 introns. The varying numbers of cis-acting elements about hormones and abiotic stress responses were distributed upstream of the promoters of SoAHL members. The SoAHL genes can be expressed in roots, leaves, and petioles, with most genes expressed at higher levels in roots. The expression of two SoAHL genes (SOV6g041850.1 and SOV2g038950.1) were significantly induced by salicylic acid treatment. The expression profiles and salicylic acid-induced expression levels of SOV2g031340.1 and SOV4g018880.1 were highly correlated with folic acid content, which may play a role in spinach response to salicylic acid signalling pathway. The transient overexpression of SOV4g018880.1 increased the folate contents of spinach leaves by 1.27 times. Our results will lay the foundation for further resolving the function of spinach AT-hook genes.

INTRODUCTION Trehalose-6-phosphate synthase (TPS) is a key enzyme involved in the synthesis of trehalose and has been reported to participate in regulating photosynthesis, carbohydrate metabolism, growth and development, and stress responses in various species. Currently, reports on TPS genes in soybean are scarce.

RATIONALE TPS is a stable non-reducing disaccharide, whose synthesis, decomposition and regulation not only provide energy for plant, but also play an important role in plant growth and development and stress tolerance. The in-depth study of soybean TPS genes and its relationships with salt stress is of great significance in elucidating the molecular mechanism of soybean salt tolerance and improving soybean yield.

RESULTS This study identified 20 soybean TPS genes and their associated 10 conserved protein motifs in the soybean genome. Molecular analysis of the promoter elements revealed that the TPS gene promoters are rich in stress-responsive elements. After salt stress treatment, the expression of 17 TPS genes changed, with 12 genes up-regulated and 5 genes down-regulated. Haplotype and selection analyses revealed two major allelic variations in TPS8, TPS13, TPS15, TPS17, and TPS18. Notably, variants carrying TPS15^H2, TPS13^H2, TPS17^H2, and TPS18^H2 were significantly enriched in improved cultivars that underwent strong artificial selection.

CONCLUSION This study reveals the molecular characteristics of the soybean TPS gene family, their expression patterns under salt stress, and their evolutionary history, providing a theoretical basis and genetic material for further elucidating the functions of soybean TPS genes and breeding salt-tolerant soybean varieties.

TPS genes were subjected to intense artificial selection. The natural variations of TPS8, TPS13, TPS15, TPS17, and TPS18 have been subjected to strong artificial selection during soybean domestication and improvement, with the variants carrying TPS15^H2, TPS13^H2, TPS17^H2, and TPS18^H2 being heavily enriched in improved cultivars.

INTRODUCTION Tomato (Solanum lycopersicum), a significant warm-season and water-dependent vegetable crop, is extensively cultivated worldwide. Whether grown in open fields or protected environments, tomatoes frequently encounter various environmental stresses, including drought and low temperatures, which significantly impact their yield and quality. Transcription factors play a pivotal role in plant stress responses by modulating the expression of specific target genes, thereby transmitting perceived stress signals downstream. WRKY transcription factors in tomatoes are known to regulate responses to multiple abiotic stresses. However, the specific role of the tomato SlWRKY45 in abiotic stress responses remains unclear.

RATIONALEStudies have demonstrated that WRKY transcription factors play a crucial regulatory role in plant responses to abiotic stress. As an important economic vegetable crop, tomato is susceptible to various environmental stresses during its growth and development. By genetically overexpressing SlWRKY45 in tomato and investigating its function under low-temperature and drought stress conditions, the findings can provide a theoretical foundation for understanding the complex regulatory mechanisms of WRKY transcription factors. Additionally, this research offers valuable candidate genes for breeding stress-resistant tomato varieties.

RESULTSExpression analysis revealed that low-temperature, drought, and abscisic acid (ABA) treatments significantly induced the expression of SlWRKY45. Overexpression of SlWRKY45 enhanced the resistance of tomato plants to drought and low-temperature stresses. Under drought and low-temperature conditions, the photosynthetic indices, antioxidant enzyme activities, and proline (Pro) contents in SlWRKY45 overexpression lines were significantly higher than those in wild-type (WT) plants. Conversely, the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) levels in SlWRKY45-OE plants was significantly lower than in WT plants under the same stress conditions. Transcriptome data analysis indicated that SlWRKY45 regulates tomato's response to low-temperature stress primarily by influencing antioxidant enzyme activities and stress response pathways. Dual-luciferase assays demonstrated that SlWRKY45 could directly activate the expression of SlPOD1. Furthermore, the interaction between SlWRKY45 and SlWRKY46 was confirmed through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays.

CONCLUSIONOur findings demonstrate that SlWRKY45 positively regulates drought resistance and low-temperature tolerance in tomato. Additionally, SlWRKY45 can interact with SlWRKY46 and directly activate the expression of SlPOD1. These results offer valuable insights for further research into the regulatory mechanisms underlying abiotic stress responses and provide potential gene resources for genetic improvement through molecular breeding.

Phenotypes of SlWRKY45-overexpressing and wild-type plants under drought and low-temperature treatments

INTRODUCTION: Identification of salt-alkali tolerant germplasm in faba bean lays the foundation for the exploration of salt-alkali tolerant genes and for the selection and breeding of salt-alkali tolerant varieties, which is of great significance for the utilization of saline-alkali land.

RATIONALE: Most of the studies on the salt-alkali tolerance of faba beans were focused on the morphological and physiological traits of the aboveground parts, while there are few studies on the phenotypic traits of the roots. The root plays a crucial role in resisting salt-alkali stress. Deep research on the relationship between the phenotypic traits of the root and the salt-alkali tolerance of faba beans will help to comprehensively understand the physiological mechanism of the salt-alkali tolerance.

RESULTS: The results showed that: (1) Under salt-alkali stress, the root overlap number was mostly affected, it was followed by the coila number, while the average diameter of root was affected slightly; (2) Between the overlap number and total number of connection points, among the bifurcation number and the overlap number and total number of connection points, most of indicators were significant positively correlation (P<0.01), while there were significant negatively correlation (P<0.01) among the average diameter of root and total number of root, the number of root tip, total length of root, endpoint number, coila number, linking number, bifurcation number, overlap number and total number of connection points; (3) Total root surface area of root, total projected area of root, total length of root and total volume of root could be used as the key indicators to identify the salt-alkali tolerance of faba bean during the germination period; (4) Two salt-alkali tolerant accessions H0000809 and H0000653, and two salt-alkali sensitive accessions H0001714 and H0002622 were screened out; and (5) The 399 faba bean accessions were divided into 4 groups: group I, salt-alkali tolerance germplasm, accounting for 0.75%; group II, moderately salt-alkali tolerant germplasm, accounting for 8%; group III, weakly saline-tolerant germplasm, accounting for 52.88%; and group IV, salt-alkali sensitive germplasm, constituting 38.35%.

CONCLUSION: Variation and correlation of each index, and the key indicators used to identify salt-alkali tolerance were determined, extreme materials can be selected and used for future study of salt-alkali tolerance mechanisms in faba bean and the excavation of salt-alkali tolerance genes.

Phenotypic differences of faba bean germplasms with different levels of salt-alkali tolerance at different growth stages (A) Root phenotype differences of faba bean germplasms with different levels of salt-alkali tolerance at germination stage (bar=5 cm); (B) Plant phenotype differences of faba bean germplasms with different levels of salt-alkali tolerance at flowering stage (bars=1 cm).

INTRODUCTION: Molecular data is one of the most important bases for many biological studies, including phylogeny, ecology, and biogeography etc. Incomplete sampling may lead to biased results and inadequate conclusions. However, few studies have evaluated current state of sampling density for sequencing DNA data comprehensively. Plastid DNA sequences have been applied in scientific studies of plants extensively due to their easy accessibility, uniparental inheritance, and moderate rate of mutation. Therefore, it is essential to investigate the current state of sampling density for sequencing plastid DNA data in species and geographic area for researchers to better utilize it.

RATIONALE: The GenBank is the biggest and most commonly used database of sequencing DNA data. The data gap of plastid DNA in species and geographic area for vascular plants was investigated based on the GenBank database in this study. Firstly, the plastid DNA data of vascular plant species were downloaded from the GenBank database and cleaned. Secondly, species names were standardized according to the World Checklist of Vascular Plants (WCVP) database. Thirdly, to evaluate the current state of sampling density for plastid DNA data of vascular plants, we counted the number of species with plastid DNA sequenced and the proportion of missing data of lineages representing orders and families. We also mapped the proportion of missing data in each region to evaluate the current state of sampling density of plastid DNA data geographically. To further investigate the potential influencing factors of the plastid DNA data gap, Spearman’s correlations between the proportion of missing data and species diversity among major groups of vascular plants or regions were calculated.

RESULTS: Only 33.75% vascular plant species have at least one record of DNA in GenBank, covering 139 005 vascular plant species (angiosperms: 131 220 species, gymnosperms: 1 154 species, and pteridophytes: 6 631 species). For data gap in species, sequenced species were unevenly sampled among lineages, with the proportion of missing data generally correlated with species richness within the lineages. The top three orders of the highest proportion of missing data were Paracryphiales, Piperales, and Dilleniales, and the top three families were Triuridaceae, Pentaphragmataceae, and Xyridaceae. For data gap in geographic area, the proportion of missing data of plastid DNA of vascular plant species showed a trend of latitudinal gradient, with the degree of missing data decreasing from the equator to the poles. Regions with high proportion of missing data usually possess high biodiversity, including many biodiversity hotspots. In addition, endemic species were generally with the high proportion of missing data in the majority of regions.

CONCLUSION:Our research evaluated the current state of sampling density for plastid DNA data in species and geographic area comprehensively. Our results suggested that about 140 000 vascular plant species have been sequenced for the plastid DNAs. However, there are still large data gaps for the plastid DNA of vascular plants in the following three aspects: (1) Only 1/3 vascular plant species have been sequenced; (2) Ratios of species with plastid DNA sequenced are uneven among lineages; (3) The proportion of missing data decreases from the equator to the poles, with more deficiencies in biodiversity hotspots and endemic species. Based on the results of this study, we propose to give priority to collection and sequencing of vascular plants for groups with high proportion of missing data and regions with high biodiversity, particularly for the endemic species. Our research points out the direction of filling plastid DNA data gap and will be beneficial to biodiversity protection.

INTRODUCTION: The cell wall-associated kinase (WAK) family has annotated approximately 130 WAK genes in the genome of rice (Oryza sativa), which play an important role in rice growth and development and stress responses.

RATIONALE: Here, we investigated the regulation and physiological mechanism of OsWAK16, an encoding gene of the cell wall-associated kinase WAK16-RLK, on rice seed vigor and anti-aging ability.

 
RESULTS: The results showed that before and after artificial aging, the seed vigor of OsWAK16 knock out mutants and overexpression lines was significantly lower and higher than that of wild-type seeds, respectively, indicating that OsWAK16 positively regulates the anti-aging ability of seeds. Physiological and biochemical analyses indicated that compared with wild-type seeds before and after artificial aging treatment, malondialdehyde (MDA) content and electrical conductivity (EC) of seed soaking solution of OsWAK16 knock out mutant seeds were significantly increased, while antioxidant enzyme activity was significantly decreased. The reverse was true in overexpression seeds. In addition, the differential expression of OsWAK16 in three types of seeds, whether artificially aged or not, also caused synergistic changes in the expression of other seed vigor-related genes OsPER1A, OsbZIP23, OsPIMT1, OsSdr4, OsMSRB5 and OsHSP18.2.

 
CONCLUSION: Therefore, it is speculated that OsWAK16 may work synergistically with other seed vigor-related genes to clear reactive oxygen species in cells, thereby regulating seed vigor and anti-aging capacity.

Tuber is a unique and extremely important organ of Cyperus esculentus, which is rich in oil and has the reproduction ability similar to seed. It is of great significance to study the specific expression genes in the tubers of C. esculentus for analyzing the regulation mechanism of tuber-specific growth and development (especially oil accumulation). Through transcriptome sequencing of the main organs (root, leaf, tillering node, stolon and tuber) of C. esculentus, the genes specifically expressed in tubers were comprehensively screened and the functions of related genes were analyzed. The results showed that a total of 155 tuber-specific expression genes were identified after multiple sets of comparative analysis by taking root, leaf, tillering node and stolon as reference, respectively. GO enrichment analysis showed that 7 GO terms including seed development, seed oilbody biogenesis, oil storage, abscisic acid response, response to abiotic stimulus and protein folding were significantly enriched, and some of the genes involved in these GO terms just reflected the unique development characteristics similar to seed of C. esculentus tubers. Among them, CESC_00080 and CESC_16572 encode caleosin, and meanwhile, CESC_08636, CESC_12549 and CESC_17828 encode oleosin, all of which are involved in the formation of plant oil bodies. Since oil body formation is a key step for plants to complete oil storage, it is indicated that the specific expression of these oil body formation-related genes in tubers may be the key to the storage of large amounts of oil in the tubers of C. esculentus. In addition, this study also screened eight tuber-specific expression transcription factor genes, such as CESC_00448 (abscisic acid insensitive 5-like protein ABI5) and CESC_03736 (heat stress transcription factor C), some of whose potential target genes were found in identified tuber-specific expression genes, indicating that these transcription factor genes may regulate the specific expression of their respective target genes. In summary, the results of this study can provide an important reference for the construction of gene regulatory networks related to tuber development of C. esculentus and the molecular mechanism analysis of tuber-specific gene expression.