Arabidopsis NUCLEAR FACTOR Y A8 inhibits the juvenile-to-adult transition by activating transcription of MIR156s

Overexpression of GhGSTF9 Enhances Salt Stress Tolerance in Transgenic Arabidopsis

Soil salinization is a major abiotic stress factor that negatively impacts plant growth, development, and crop yield, severely limiting agricultural production and economic development. Cotton, a key cash crop, is commonly cultivated as a pioneer crop in regions with saline-alkali soil due to its relatively strong tolerance to salt. This characteristic renders it a valuable subject for investigating the molecular mechanisms underlying plant salt tolerance and for identifying genes that confer salt tolerance. In this study, focus was placed on examining a salt-tolerant variety, E991, and a salt-sensitive variety, ZM24. A combined analysis of transcriptomic data from these cotton varieties led to the identification of potential salt stress-responsive genes within the glutathione S-transferase (GST) family. These versatile enzyme proteins, prevalent in animals, plants, and microorganisms, were demonstrated to be involved in various abiotic stress responses. Our findings indicate that suppressing GhGSTF9 in cotton led to a notably salt-sensitive phenotype, whereas heterologous overexpression in Arabidopsis plants decreases the accumulation of reactive oxygen species under salt stress, thereby enhancing salt stress tolerance. This suggests that GhGSTF9 serves as a positive regulator in cotton's response to salt stress. These results offer new target genes for developing salt-tolerant cotton varieties.

Nuclear factor Y-A3b binds to the SINGLE FLOWER TRUSS promoter and regulates flowering time in tomato

The control of flowering time is essential for reproductive success and has a major effect on seed and fruit yield and other important agricultural traits in crops. Nuclear factors Y (NF-Ys) are transcription factors that form heterotrimeric protein complexes to regulate gene expression required for diverse biological processes, including flowering time control in plants. However, to our knowledge, there has been no report on mutants of individual NF-YA subunits that promote early flowering phenotype in plants. In this study, we identified SlNF-YA3b, encoding a member of the NF-Y transcription factor family, as a key gene regulating flowering time in tomato. Knockout of NF-YA3b resulted in an early flowering phenotype in tomato, whereas overexpression of NF-YA3b delayed flowering in transgenic tomato plants. NF-YA3b was demonstrated to form heterotrimeric protein complexes with multiple NF-YB/NF-YC heterodimers in yeast three-hybrid assays. Biochemical evidence indicated that NF-YA3b directly binds to the CCAAT cis-elements of the SINGLE FLOWER TRUSS (SFT) promoter to suppress its gene expression. These findings uncovered a critical role of NF-YA3b in regulating flowering time in tomato and could be applied to the management of flowering time in crops.

GhCOL2 Positively Regulates Flowering by Activating the Transcription of GhHD3A in Upland Cotton (Gossypium hirsutum L.)

Plants have evolved sophisticated signaling networks to adjust flowering time, ensuring successful reproduction. Two crucial flowering regulators, FLOWERING LOCUS T (FT) and CONSTANS (CO), play pivotal roles in regulating flowering across various species. Previous studies have indicated that suppressing Gossypium hirsutum CONSTANS-LIKE 2 (GhCOL2), a homolog of Arabidopsis CO, leads to delayed flowering in cultivated cotton. However, the underlying regulatory mechanisms remain unknown. In this study, a yeast one-hybrid and dual-LUC expression assays were used to elucidate the molecular mechanism through which GhCOL2 regulates the transcription of GhHD3A. RT-qPCR was used to examine the expression of GhCOL2 and GhHD3A. Our findings reveal that GhCOL2 directly binds to CCACA cis-elements and atypical CORE (TGTGTATG) cis-elements in the promoter regions of HEADING DATE 3 A (HD3A), thereby activating GhHD3A transcription. Notably, GhCOL2 and GhHD3A exhibited high expression levels in the adult stage and low levels in the juvenile stage. Interestingly, the expression of GhCOL2 and GhHD3A varied significant between the two cotton varieties (Tx2094 and Maxxa). In summary, our study enhances the understanding of the molecular mechanism by which cotton GhCOL2-GhHD3A regulates flowering at the molecular level. Furthermore, it contributes to a broader comprehension of the GhCOL2-GhHD3A model in G. hirsutum.

Temporal regulation of vegetative phase change in plants

During their vegetative growth, plants reiteratively produce leaves, buds, and internodes at the apical end of the shoot. The identity of these organs changes as the shoot develops. Some traits change gradually, but others change in a coordinated fashion, allowing shoot development to be divided into discrete juvenile and adult phases. The transition between these phases is called vegetative phase change. Historically, vegetative phase change has been studied because it is thought to be associated with an increase in reproductive competence. However, this is not true for all species; indeed, heterochronic variation in the timing of vegetative phase change and flowering has made important contributions to plant evolution. In this review, we describe the molecular mechanism of vegetative phase change, how the timing of this process is controlled by endogenous and environmental factors, and its ecological and evolutionary significance.

Identification, characterization, and validation of NBS-encoding genes in grass pea

Grass pea is a promising crop with the potential to provide food and fodder, but its genomics has not been adequately explored. Identifying genes for desirable traits, such as drought tolerance and disease resistance, is critical for improving the plant. Grass pea currently lacks known R-genes, including the nucleotide-binding site-leucine-rich repeat (NBS-LRR) gene family, which plays a key role in protecting the plant from biotic and abiotic stresses. In our study, we used the recently published grass pea genome and available transcriptomic data to identify 274 NBS-LRR genes. The evolutionary relationships between the classified genes on the reported plants and LsNBS revealed that 124 genes have TNL domains, while 150 genes have CNL domains. All genes contained exons, ranging from 1 to 7. Ten conserved motifs with lengths ranging from 16 to 30 amino acids were identified. We found TIR-domain-containing genes in 132 LsNBSs, with 63 TIR-1 and 69 TIR-2, and RX-CCLike in 84 LsNBSs. We also identified several popular motifs, including P-loop, Uup, kinase-GTPase, ABC, ChvD, CDC6, Rnase_H, Smc, CDC48, and SpoVK. According to the gene enrichment analysis, the identified genes undergo several biological processes such as plant defense, innate immunity, hydrolase activity, and DNA binding. In the upstream regions, 103 transcription factors were identified that govern the transcription of nearby genes affecting the plant excretion of salicylic acid, methyl jasmonate, ethylene, and abscisic acid. According to RNA-Seq expression analysis, 85% of the encoded genes have high expression levels. Nine LsNBS genes were selected for qPCR under salt stress conditions. The majority of the genes showed upregulation at 50 and 200 μM NaCl. However, LsNBS-D18, LsNBS-D204, and LsNBS-D180 showed reduced or drastic downregulation compared to their respective expression levels, providing further insights into the potential functions of LsNBSs under salt stress conditions. They provide valuable insights into the potential functions of LsNBSs under salt stress conditions. Our findings also shed light on the evolution and classification of NBS-LRR genes in legumes, highlighting the potential of grass pea. Further research could focus on the functional analysis of these genes, and their potential use in breeding programs to improve the salinity, drought, and disease resistance of this important crop.

QTL Mapping and Transcriptome Analysis Reveal Candidate Genes Regulating Seed Color in Brassica napus

Yellow seeds are desirable in rapeseed breeding because of their higher oil content and better nutritional quality than black seeds. However, the underlying genes and formation mechanism of yellow seeds remain unclear. Here, a novel yellow-seeded rapeseed line (Huangaizao, HAZ) was crossed with a black-seeded rapeseed line (Zhongshuang11, ZS11) to construct a mapping population of 196 F₂ individuals, based on which, a high-density genetic linkage map was constructed. This map, comprising 4174 bin markers, was 1618.33 cM in length and had an average distance of 0.39 cM between its adjacent markers. To assess the seed color of the F₂ population, three methods (imaging, spectrophotometry, and visual scoring) were used and a common major quantitative trait locus (QTL) on chromosome A09, explaining 10.91-21.83% of the phenotypic variance, was detected. Another minor QTL, accounting for 6.19-6.69% of the phenotypic variance, was detected on chromosome C03, only by means of imaging and spectrophotometry. Furthermore, a dynamic analysis of the differential expressions between the parental lines showed that flavonoid biosynthesis-related genes were down-regulated in the yellow seed coats at 25 and 35 days after flowering. A coexpression network between the differentially expressed genes identified 17 candidate genes for the QTL intervals, including a flavonoid structure gene, novel4557 (BnaC03.TT4), and two transcription factor genes, namely, BnaA09G0616800ZS (BnaA09.NFYA8) and BnaC03G0060200ZS (BnaC03.NAC083), that may regulate flavonoid biosynthesis. Our study lays a foundation for further identifying the genes responsible for and understanding the regulatory mechanism of yellow seed formation in Brassica napus.

Light-Dependent Regulatory Interactions between the Redox System and miRNAs and Their Biochemical and Physiological Effects in Plants

Light intensity and spectrum play a major role in the regulation of the growth, development, and stress response of plants. Changes in the light conditions affect the formation of reactive oxygen species, the activity of the antioxidants, and, consequently, the redox environment in the plant tissues. Many metabolic processes, thus the biogenesis and function of miRNAs, are redox-responsive. The miRNAs, in turn, can modulate various components of the redox system, and this process is also associated with the alteration in the intensity and spectrum of the light. In this review, we would like to summarise the possible regulatory mechanisms by which the alterations in the light conditions can influence miRNAs in a redox-dependent manner. Daily and seasonal fluctuations in the intensity and spectral composition of the light can affect the expression of miRNAs, which can fine-tune the various physiological and biochemical processes due to their effect on their target genes. The interactions between the redox system and miRNAs may be modulated by light conditions, and the proposed function of this regulatory network and its effect on the various biochemical and physiological processes will be introduced in plants.

The miR169b/NFYA1 module from the halophyte Halostachys caspica endows salt and drought tolerance in Arabidopsis through multi-pathways

Salt and drought are the major abiotic stress factors plaguing plant growth, development and crop yields. Certain abiotic-stress tolerant plants have developed special mechanisms for adapting to adverse environments in the long process of evolution. Elucidating the molecular mechanisms by which they can exert resistance to abiotic stresses is beneficial for breeding new cultivars to guide agricultural production. Halostachys caspica, a perennial halophyte belonging to Halostachys in Amaranthaceae, is extremely tolerant to harsh environments, which is commonly grown in the saline-alkali arid desert area of Northwest, China. However, the molecular mechanism of stress tolerance is unclear. Nuclear Factor Y-A (NFYA) is a transcription factor that regulates the expression of downstream genes in plant response to adverse environments. It has also been reported that some members of the NFYA family are the main targets of miR169 in plants. In this study, we mainly focused on exploring the functions and preliminary mechanism of the miR169b/NFYA1 module from H. caspica to abiotic stress. The main results showed that RLM-RACE technology validated that HcNFYA1 was targeted by HcmiR169b, qRT-PCR revealed that HcmiR169b was repressed and HcNFYA1 was induced in the H. caspica branches under various abiotic stress as well ABA treatment and Arabidopsis stable transformation platform with molecular methods was applied to elucidate that the HcmiR169b/HcNFYA1 module conferred the salt and drought tolerance to plants by enhancing ABA synthesis and ABA signal transduction pathways, maintaining ROS homeostasis and the stability of cell membrane. HcNFYA1 is expected to be a candidate gene to improve plant resistance to salt and drought stresses.

Convergent evolution of the annual life history syndrome from perennial ancestors

Despite most angiosperms being perennial, once-flowering annuals have evolved multiple times independently, making life history traits among the most labile trait syndromes in flowering plants. Much research has focused on discerning the adaptive forces driving the evolution of annual species, and in pinpointing traits that distinguish them from perennials. By contrast, little is known about how 'annual traits' evolve, and whether the same traits and genes have evolved in parallel to affect independent origins of the annual syndrome. Here, we review what is known about the distribution of annuals in both phylogenetic and environmental space and assess the evidence for parallel evolution of annuality through similar physiological, developmental, and/or genetic mechanisms. We then use temperate grasses as a case study for modeling the evolution of annuality and suggest future directions for understanding annual-perennial transitions in other groups of plants. Understanding how convergent life history traits evolve can help predict species responses to climate change and allows transfer of knowledge between model and agriculturally important species.

Involvement of PtCOL5-PtNF-YC4 in reproductive cone development and gibberellin signaling in Chinese pine

It is well documented that the CO/NF-YB/NF-YC trimer (NF-Y-CO) binds and regulates the FT promoter. However, the FT/TFL1-like (FLOWERING LOCUS T/TERMINALFLOWER1-like) genes in gymnosperms are all flowering suppressors, and the regulation model of NF-Y in gymnosperms is different from that in angiosperms. Here, using Chinese pine (Pinus tabuliformis), we identified a CONSTANS-LIKE gene, PtCOL5, the expression of which was strongly induced during cones development and it functioned as a repressor of flowering. PtNF-YC4, which interacted with PtCOL5, was highly correlated with PtCOL5 during growth and development, has been demonstrated. Moreover, PtNF-YC4 and PtCOL5 can bind to PtTFL2 promoter, and their interaction can enhance PtTFL2 expression. Interestingly, we found PtNF-YC4 and PtCOL5 were involved in gibberellin signaling and their interaction was inhibited by PtDELLA protein, thus affecting PtTFL2 expression. Collectively, PtCOL5-PtNF-YC4 was involved in reproductive cone development and gibberellin signaling in Chinese pine. Our findings uncovered reproductive cone development and signal transduction mechanism of COL-NF-Y in gymnosperms.

Over-Expression of Larch DAL1 Accelerates Life-Cycle Progression in Arabidopsis

Homologs of Larix kaempferiDEFICIENS-AGAMOUS-LIKE 1 (LaDAL1) promote flowering in Arabidopsis. However, their functional role in the whole life-cycle is limited. Here, we analyzed the phenotypes and transcriptomes of Arabidopsis plants over-expressing LaDAL1. With respect to the defined life-cycle stage of Arabidopsis based on the meristem state, the results showed that LaDAL1 promoted seed germination, bolting, flower initiation, and global proliferative arrest, indicating that LaDAL1 accelerates the meristem reactivation, the transitions of vegetative meristem to inflorescence and flower meristem, and meristem arrest. As a marker gene of meristem, TERMINAL FLOWER 1 was down-regulated after LaDAL1 over-expression. These results reveal that LaDAL1 accelerates the life-cycle progression in Arabidopsis by promoting the transition of meristem fate, providing more and novel functional information about the conifer age-related gene DAL1.

CRISPR-Cas9 mediated OsMIR168a knockout reveals its pleiotropy in rice

MicroRNA168 (MIR168) is a key miRNA that targets the main RNA-induced silencing complex component Argonaute 1 (AGO1) to regulate plant growth and environmental stress responses. However, the regulatory functions of MIR168 need to be further elucidated in rice. In this paper, we generated clean OsMIR168a deletion mutants by CRISPR-Cas9 strategy. We then phenotypically and molecularly characterized these mutants. The rice OsMIR168a mutants grew rapidly at the seedling stage, produced more tillers and matured early. Compared to the wild-type plants, the mutants were shorter at maturity and produced smaller spikelets and seeds. Analysis of gene expression showed that the transcription levels of OsMIR168a's target genes such as OsAGO1a, OsAGO1b and OsAGO1d were elevated significantly in the OsMIR168a mutants. Intriguingly, OsAGO18, a member of a new AGO clade that is conserved in monocots, was confirmed to be a target of OsMIR168a not only by informatic prediction but also by expression analysis and a cell-based cleavage assay in the OsMIR168a mutants. Many protein-coding genes and miRNAs showed differential expression in the OsMIR168a mutants, suggesting OsMIR168a exerts a major transcriptional regulatory role, likely through its potential target genes such as OsAGO1s and OsAGO18. KEGG enrichment analysis of these differentially expressed genes pointed to OsMIR168a's involvement in important processes such as plant hormone signalling transduction and plant-pathogen interaction. These data collectively support that the complex regulation module of OsMIR168a-OsAGO1/OsAGO18-miRNAs-target genes contributes to agronomically important traits, which sheds light on miRNA-mediated crop breeding.

VAL genes regulate vegetative phase change via miR156-dependent and independent mechanisms

How organisms control when to transition between different stages of development is a key question in biology. In plants, epigenetic silencing by Polycomb repressive complex 1 (PRC1) and PRC2 plays a crucial role in promoting developmental transitions, including from juvenile-to-adult phases of vegetative growth. PRC1/2 are known to repress the master regulator of vegetative phase change, miR156, leading to the transition to adult growth, but how this process is regulated temporally is unknown. Here we investigate whether transcription factors in the VIVIPAROUS/ABI3-LIKE (VAL) gene family provide the temporal signal for the epigenetic repression of miR156. Exploiting a novel val1 allele, we found that VAL1 and VAL2 redundantly regulate vegetative phase change by controlling the overall level, rather than temporal dynamics, of miR156 expression. Furthermore, we discovered that VAL1 and VAL2 also act independently of miR156 to control this important developmental transition. In combination, our results highlight the complexity of temporal regulation in plants.

During their life-cycles multicellular organisms progress through a series of different developmental phases. The correct timing of the transitions between these phases is essential to ensure that development occurs at an appropriate rate and in the right order. In plants, vegetative phase change—the switch from a juvenile to an adult stage of vegetative growth prior to the onset of reproductive development–is a widely conserved transition associated with a number of phenotypic changes. It is therefore an excellent model to investigate the regulation of developmental timing. The timing of vegetative phase change is determined by a decline in the expression of a regulatory microRNA–miRNA156. However, what controls the temporal decline in miR156 expression is a major unknown in the field. In this study we tested whether members of the VAL gene family, known to be important for coordinating plant developmental transitions, are critical regulators of vegetative phase change. Using a series of genetic and biochemical approaches we found that VAL genes are important determinants of the timing of vegetative phase change. However, we discovered that VAL genes function largely to control the overall level, rather than temporal expression pattern, of miR156.

Beyond the Genetic Pathways, Flowering Regulation Complexity in Arabidopsis thaliana

Flowering is one of the most critical developmental transitions in plants’ life. The irreversible change from the vegetative to the reproductive stage is strictly controlled to ensure the progeny’s success. In Arabidopsis thaliana, seven flowering genetic pathways have been described under specific growth conditions. However, the evidence condensed here suggest that these pathways are tightly interconnected in a complex multilevel regulatory network. In this review, we pursue an integrative approach emphasizing the molecular interactions among the flowering regulatory network components. We also consider that the same regulatory network prevents or induces flowering phase change in response to internal cues modulated by environmental signals. In this sense, we describe how during the vegetative phase of development it is essential to prevent the expression of flowering promoting genes until they are required. Then, we mention flowering regulation under suboptimal growing temperatures, such as those in autumn and winter. We next expose the requirement of endogenous signals in flowering, and finally, the acceleration of this transition by long-day photoperiod and temperature rise signals allowing A. thaliana to bloom in spring and summer seasons. With this approach, we aim to provide an initial systemic view to help the reader integrate this complex developmental process.

MicroRNA annotation in plants: current status and challenges

Last two decades, the studies on microRNAs (miRNAs) and the numbers of annotated miRNAs in plants and animals have surged. Herein, we reviewed the current progress and challenges of miRNA annotation in plants. Via the comparison of plant and animal miRNAs, we pinpointed out the difficulties on plant miRNA annotation and proposed potential solutions. In terms of recalling the history of methods and criteria in plant miRNA annotation, we detailed how the major progresses made and evolved. By collecting and categorizing bioinformatics tools for plant miRNA annotation, we surveyed their advantages and disadvantages, especially for ones with the principle of mimicking the miRNA biogenesis pathway by parsing deeply sequenced small RNA (sRNA) libraries. In addition, we summarized all available databases hosting plant miRNAs, and posted the potential optimization solutions such as how to increase the signal-to-noise ratio (SNR) in these databases. Finally, we discussed the challenges and perspectives of plant miRNA annotations, and indicated the possibilities offered by an all-in-one tool and platform according to the integration of artificial intelligence.