With the sharp change of the global climate, the ecological environment for plant is becoming increasingly harsh, therefore the molecular mechanisms underlying how circadian synergistically interacts with light or temperature receptors to transmit environmental signals and rhythmically regulate various growth and development process received widespread attention. As an endogenous timer of plants, the core oscillator of circadian clock is composed of multiple coupled transcriptional-translational feedback loops (TTFL), and it is modified from transcription, post-transcription, translation, post-translation to epigenetic levels. These multi-precise regulatory mechanisms ensure that the circadian clock can be synchronized and reset by external signals, so that the endogenous rhythm matches with external cycles, thereby endowing plants with the ability to optimize resource utilization and tend towards the optimal growth, which also has an important significance for guiding the genetic improvement and domestication of crops. In this review, we summarized the multi-level of regulatory mechanisms of core oscillator as well as the molecular function of circadian homologous genes in crops, thoroughly described the interaction network between the circadian clock and the light and temperature signal pathways and give prospects for molecular breeding based on the opinion, which provides new ideas for expanding the environmental adaptability and optimizing agronomic traits of crops.

INTRODUCTION: As the main grain crop, rice plays an important role in ensuring food security of China. Rise in global average temperature is detrimental to crop yield and heat stress is currently one of the major abiotic threats on rice production. There are significant variations in heat tolerance among different rice varieties. As a typical quantitative trait, heat tolerance of rice is controlled by multiple genes. Identification of new QTLs and genes related to heat tolerance is very important for the genetic research and the breeding of new heat-tolerant rice varieties.

RATIONALE:In recent years, many heat tolerant QTLs had been identified with different genetic populations and evaluation indicators at different growth stages. Most of those QTLs were mapped in large intervals due to the limited population sizes, simplified experimental designs and inaccurately controlled environments. The heat tolerance level identification in a population is very difficult for mature plants. Therefore, we developed a population of recombinant inbred lines (RILs) with 186 lines derived from japonica rice TD70 and indica rice Kasalath, which showed large variations in seedling survival rates under high temperature stress (HTSR). QTLs associated with HTSR were mapped by the high-density linkage Bin-map and candidate genes were identified.

RESULTS: Twenty-six QTLs related to the HTSR were mapped on 11 of the 12 chromosomes, with the exception of 3. The LOD values of single QTL ranged from 2.59-16.15, four of which with LOD values greater than 10. Seven QTLs were located within the same interval or adjacent to known heat tolerance QTLs. The major locus of qHTSR5.2 was located in the 26.25-26.38 Mb region of Chr. 5 with an LOD value of 12.07, which explained 7.18% of the total phenotypic variation in the HTSR. According to the annotation and sequence analysis of the 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. Five of them were identified as potential candidate genes because the RILs sharing each of the distinct haplotypes of their parents for each gene exhibited significant different HTSR resistance level. Among them, three candidate genes encode heat shock proteins HSP20 or HSP17.5.

CONCLUSION: We detected 26 QTLs controlling seedling heat tolerance based on a high-density Bin map in a RIL population. Some of the QTLs were overlapped with known heat tolerance loci, indicating their strong effects on regulating heat tolerance of rice. Five candidate genes were identified through gene annotation, parental sequence comparison, effect analysis of heat tolerance between RILs with different haplotypes. The candidate genes identified in our study could be used for molecular mechanism research on high temperature tolerance of rice in the future.

Mapping of QTL for heat tolerance at seedling stage in rice based on a high-density Bin map. Heat tolerance of parents and RILs population during seedling stage. Location of QTLs contributing to heat tolerance at seedling stage.

INTRODUCTION:Plant growth regulators are natural or artificially synthesized chemical substances that play an important regulatory role in the growth and development of crops, and can enhance the resistance of plants to stress.

RATIONALE 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-alkali land, we conducted spraying experiments on wheat in saline-alkali 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 aligosaccharide group, a Plant Gold group, and a mixed group of 0.5% alginate aligosaccharide and Plant Gold. The wheat was sprayed on March 28, April 12, April 28, and May 12, 2024.

RESULTS: The results showed that after spraying alginate oligosaccharide and its mixture with Plant Gold, the number of grains per ear and the 100-grain weight of wheat significantly increased. In particular, the group that received the mixture of alginate oligosaccharide and Plant Gold achieved a theoretical yield of 1 174.5 kg·hm^-2 for wheat in saline-alkali soil, which was an increase of 14.4% and 46.9% compared to the groups treated with only alginate oligosaccharide and Plant Gold, respectively.

CONCLUSION: Therefore, the combined application of alginate oligosaccharide and Plant Gold can significantly enhance the adaptability of wheat in saline-alkali land, demonstrating its important application potential in wheat production in such environments.

After selecting 1 m × 1 m sample plots within the experimental block and conducting spray tests with different plant growth regulators, the theoretical yields of different groups showed different changes. Among them, the yield of the mixed spray group was significantly higher than that of the control group.

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 (Brassica oleracea var. acephala) 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 biosynthetic 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 B. oleraceavar. acephala, 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 genome of B. oleracea. Based on these sequences, eight 5'-nucleotidase candidate genes were successfully cloned from B. 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 E. 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 had only weak catalytic activity against GMP.

CONCLUSION: The 5'-nucleotidase gene from the HAD and SurE families of B. oleracea var. acephalawas cloned and phylogenetic analysis showed that it was conserved in plants. 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 new germplasm with high NMN content.

Cloning and functional analysis of 5'-nucleotidase gene catalyzing NMN degradation to NR inBrassica oleraceavar. acephala.The 5'-nucleotidase gene of B. oleraceavar. acephala was successfully 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. In vitro enzymatic experiments showed that 5'-nucleotidase could catalyze the dephosphorylation of NMN to NR, and had catalytic effects on NaMN, purine nucleotides (AMP, GMP) and pyrimidine nucleotides (CMP, UMP).

INTRODUCTION: The AT-hook motif nuclear localized (AHL) gene family is a highly conserved transcription factors involved in plant growth, development, and stress responses, but their roles in spinach are still unknown.

RATIONALE:To reveal the basic characteristics of the AHL family in spinach, members of the spinach SoAHLfamily 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.

RESULTS: The results revealed 19 SoAHL family members in the 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. The sequence composition of PPC and AT-hook conserved motifs varies among subfamilies; most of the SoAHL genes are located in the nucleus, cytoplasm, and mitochondrion. Members of subfamily I of SoAHL have no introns, whereas members of subfamily II contain 4-5 introns. The varying numbers of cis-acting elements relate to phytohormones and abiotic stress responses were distributed upstream of the promoters of the SoAHL members. The SoAHL genes can be expressed in roots, leaves, and petioles, with most genes expressed at relatively high levels in roots. The expression of two SoAHL genes (SOV6g041850.1 and SOV2g038950.1) was 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 the folic acid content, which may play a role in the spinach response to the salicylic acid signaling pathway. The transient overexpression of SOV4g018880.1 increased the folate content of spinach leaves by 1.75 times.

CONCLUSION: The results from the sequence characteristics, expression profiles and exogenous salicylic acid treatment revealed that the SoAHLs had potential functional diversity and that specific members may have positive effects on spinach folate accumulation. Our results will lay the foundation for further resolving the function of spinach AT-hook genes.

Phenotype (A), total folate content (B) and expression analysis of SoAHL (C) under 50 μmol∙L^-1 salicylic acid (SA) treatment for 5 days (D5) and 7 days (D7). CK: Control

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 GolSgene family 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. 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 various degrees after salt treatment, suggesting their potential involvement in salt stress response in L. indica.

CONCLUSION: This study systematically identified and characterized the LiGolS gene family members in L. indica, 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.

Expression patterns of LiGolS genes in Lagerstroemia indica under salt treatment

(A) Cloud and rain map of LiGolS gene expression in salt-sensitive L. indica cultivars under normal and salt treatment conditions; (B) Cloud and rain map of LiGolS gene expression in salt-tolerant L. indica cultivars under normal and salt treatment conditions; (C) LiGolS gene expression in different varieties of L. indica under normal and salt treatment conditions; (D) Heatmap of LiGolS gene expression patterns before and under salt treatment, this heatmap illustrated the log₂-transformed expression levels of LiGolS genes before and after salt treatment (yellow modules indicate higher expression levels, while green modules indicate lower expression levels). M-CK and N-CK indicate salt-sensitive and salt-tolerant cultivars under normal conditions, respectively; M-T and N-T indicate salt-sensitive and salt-tolerant groups under salt treatment conditions, respectively.

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 nucleotide polymorphisms (SNPs), and subsequently population genetics and landscape genetics together with species distribution modelling were analyzed.

RESULTS: B. 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 differences 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 difference, 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: B. 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 provide the basis for conservation and utilization of B. densiflorum.

Population genetic structure analysis of Brachystachyum densiflorum

INTRODUCTION:An efficient Agrobacterium rhizogenes-mediated transformation system for Pueraria lobata was established.

RATIONALE: In this study, tissue-cultured plantlets of P. lobata were used as explants to investigate the effects of different genotypes, A. rhizogenes strains, explants, precultivation times, infection times, culture days, subculture times, and culture methods on the efficiency of hairy root genetic transformation in P. lobata.

RESULTS: The results indicated that the induction rate of hairy root formation was the highest when the immature leaves of YG-19 were used as the explant material, reaching 10.2%. A. rhizogenes K599 was identified as the most suitable strain. The optimal explant material was immature leaves that had just unfolded from the first to second nodes of the 5^th to 13^th generation tissue culture plantlets subcultured for 8 days. After 3 days of pre-culture and 15 minutes of bacterial infection, the highest induction rate of hairy roots reached 22.4%. The optimal type of culture medium for the proliferation of hairy roots in P. lobatawas solid medium culture, and the fresh weight of hairy roots grown on solid medium was 75 times greater than that of hairy roots grown in liquid medium. PCR detection and fluorescence microscopy assays revealed that the expression of GFP and rolB genes in the hairy roots of P. lobata was stable, and the rate of cotransformation was 80%.

CONCLUSION: Genotype, A. rhizogenes strain, and culture duration were the most critical factors for the efficient genetic transformation of hairy roots in P. lobata.

The external environment severely affects growth and development of plants. In recent years, the increasing extreme climates have posed a serious threat to the growth and development of plants. Understanding the regulatory mechanisms of plant stress tolerance is of great significance for ensuring the survival and development of plants (especially economic crops) and their yields. Alternative splicing is an important post-transcriptional regulatory mechanism and plays an important role in the diversity of plant gene functions and stress resistance. At present, a variety of alternative splicing variants of stress-resistant related genes have been identified in different plant species, and several regulatory mechanisms involved in alternative splicing have been elucidated, effectively advancing the relevant theoretical basis for plant stress resistance in plants. This paper reviews the types and splicing mechanisms of alternative splicing in plants, highlights the recent progress in alternative splicing regulation of plant responses to abiotic stress, and provides a prospect for the future direction of research on alternative splicing in plants.

UV-B, as an inherent constituent of sunlight, exerts a crucial influence on the growth and development of plants. Recent studies showed that UV-B is not merely an environmental stressor, but also a functional signal molecule that is able to promote plant growth under moderate radiation level. The protein UVR8, as a unique photoreceptor specific to UV-B, plays an irreplaceable role in the plant's response to UV-B, whose functions are regulated by both upstream and downstream transcription factors. At present, a variety of transcription factors such as BBXs, WRKYs, MYBs, and PIFs have been reported to be involved in UV-B regulated processes like hypocotyl elongation, primary root length, leaf size and shape, flowering cycle, and anthocyanin synthesis. This article reviews the molecular mechanisms of UVR8 in the UV-B signaling pathway and summarizes the regulatory mechanisms of the transcription factors during the UV-B radiation process, to provide reference for relevant research.

Coumarins are a class of phenolic compounds with benzopyrones as the parent ring structure, categorized into simple and complex coumarins, and widely distributed in higher plants. In recent years, studies have shown that root-secreted coumarins can promote iron absorption in plants. Here, the recent progress in the discovery and identification of genes related to the biosynthesis and regulation of plant iron deficiency-induced coumarins is reviewed, and the molecular mechanisms of the biosynthesis, storage, secretion, and regulation of iron deficiency-induced coumarins are further elaborated. The mechanism by which coumarins could promote plant iron uptake has also been discussed. Finally, this paper provides a preliminary outlook on the future research directions to gain knowledge of these mechanisms, which could offer novel opportunities to generate iron deficiency-tolerant crops and iron-biofortified crops.

The organs abscission is a phenomenon in which parts of organs are separated from the body. It is an adaptive strategy evolved by plants in the process of growth and response to environmental changes, which ensures the normal growth and adaptation of plants to the environment. This process involves the abscission zone formation, signal activation, cell separation, and is regulated by both internal (in vivo) physiological processes and external environmental factors including light, temperature, and humidity. In agricultural production, the abscission of plant organs directly affects crop yield. Understanding the regulatory mechanisms of plant organ abscission is greatly important for improving crop yield. In recent years, tremendous progress has been made in the study of organ abscission mechanisms. The studies showed that the mechanisms of organ abscission in plants are largely conservative between species, but also with significant variations. This review delved into the physiological and biochemical mechanisms of plant organ abscission, and summarized the effects of both the environmental factors and the hormones and enzymes in the process. The review provides a solid theoretical support and practical guidance for crop genetic breeding and agricultural production improvement in connection with organ abscission.