Plant Flowering Research Articles

Coordination of shoot apical meristem shape and identity by APETALA2 during floral transition in Arabidopsis

Plants flower in response to environmental signals. These signals change the shape and developmental identity of the shoot apical meristem (SAM), causing it to form flowers and inflorescences. We show that the increases in SAM width and height during floral transition correlate with changes in size of the central zone (CZ), defined by CLAVATA3 expression, and involve a transient increase in the height of the organizing center (OC), defined by WUSCHEL expression. The APETALA2 (AP2) transcription factor is required for the rapid increases in SAM height and width, by maintaining the width of the OC and increasing the height and width of the CZ. AP2 expression is repressed in the SAM at the end of floral transition, and extending the duration of its expression increases SAM width. Transcriptional repression by SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) represents one of the mechanisms reducing AP2 expression during floral transition. Moreover, AP2 represses SOC1 transcription, and we find that reciprocal repression of SOC1 and AP2 contributes to synchronizing precise changes in meristem shape with floral transition.

Floral volatile benzenoids/phenylpropanoids: biosynthetic pathway, regulation and ecological value.

Benzenoids/phenylpropanoids, the second most diverse group of plant volatiles, exhibit significant structural diversity and play crucial roles in attracting pollinators and protecting against pathogens, insects, and herbivores. This review summarizes their complex biosynthetic pathways and regulatory mechanisms, highlighting their links to plant growth, development, hormone levels, circadian rhythms, and flower coloration. External factors like light, humidity, and temperature also influence their biosynthesis. Their ecological value is discussed, offering insights for enhancing floral scent, pollinator attraction, pest resistance, and metabolic engineering through genetic modification.

Characterization of the roles of MiSPL4a and MiSPL4b in flowering time and drought resistance in Arabidopsis

SQUAMOSA promoter-binding protein-like 3/4/5 (SPL3/4/5) genes are involved mainly in regulating plant flowering through the gibberellin and age pathways. In our previous study, two SPL4-like genes, MiSPL4a and MiSPL4b (MiSPL4a/b), were identified and analyzed in mango, and their highest expression levels were detected in flowers. However, the functions of MiSPL4a and MiSPL4b in mango remain unclear. In this study, bioinformatics, expression, function and interacting proteins were analyzed. The results revealed that MiSPL4a was highly expressed in leaves at the early stage of the flower induction period, while MiSPL4b increased the highest expression peak during the vegetative period. MiSPL4a/b genes were induced by drought treatment. Overexpression of MiSPL4a/b accelerated early flowering and increased the expression levels of several flowering-related genes, such as APETALA1 (AtAP1), FRUITFULL (AtFUL), and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (AtSOC1) in Arabidopsis thaliana. The MiSPL4a/b transgenic plants presented increased resistance to drought and abscisic acid (ABA) treatment, and the MiSPL4b transgenic plants were sensitive to prohexadione-calcium (Pro-Ca) treatment. In addition, MiSPL4a and MiSPL4b interact with MiSOC1, Mi14–3–3, and several stress-related proteins. In summary, these findings indicated that in transgenic Arabidopsis, MiSPL4a/b genes have the function of accelerating flowering and enhancing stress resistance.

Negative and sex-specific effects of drought on flower production, resources and pollinator visitation, but not on floral scent in monoecious Cucurbita pepo.

The globally changing climatic condition is increasing the incidences of drought in several parts of the world. This is predicted and already shown to not only impact plant growth and flower development, but also plant-pollinator interactions and the pollination success of entomophilous plants. However, there is a large gap in our understanding of how drought affects the different flowers and pollen transfer among flowers in sexually polymorphic species. Here, we evaluated in monoecious Styrian oil pumpkin, and separately for female and male flowers, the responses of drought stress on flower production, petal size, nectar, floral scent and visitation by bumblebee pollinators. Drought stress adversely affected all floral traits studied, except floral scent. Although both flower sexes were adversely affected by drought stress, the effects were more severe on female flowers, with most of the female flowers even aborted before opening. The drought had negative effects on floral visitation by the pollinators, which generally preferred female flowers. Overall, our study highlights that the two flower sexes of a monoecious plant species are differently affected by drought stress and calls for further investigations to better understand the cues used by the pollinators to discriminate against male flowers and against flowers of drought-stressed plants.

CIRCADIAN CLOCK-ASSOCIATED1 Delays Flowering by Directly Inhibiting the Transcription of BcSOC1 in Pak-choi.

Flowering is critical to the success of plant propagation. The MYB family transcription factor CIRCADIAN CLOCK-ASSOCIATED1 (CCA1) is an essential component of the core loop of the circadian clock and plays a crucial role in regulating plant flowering time. In this study, we found that photoperiod affects the expression pattern and expression level of BcCCA1, which is delayed flowering time under short-day conditions in Pak-choi [Brassica campestris (syn. Brassica rapa) ssp. chinensis]. We detected overexpression and silencing of BcCCA1 in Pak-choi, resulting in delayed and promoted flowering time, respectively. Furthermore, we also discovered that FLOWERING LOCUS C (BcFLC) and SUPPRESSOR OF CONSTANS1 (BcSOC1) were expressed significantly differently in BcCCA1 overexpression and silencing plants compared with control plants. Therefore, we further investigated the interaction relationship between BcCCA1, BcFLC, and BcSOC1, and the results showed that BcCCA1 and BcFLC as a complex interacted with each other. Moreover, both BcCCA1 and BcFLC can directly bind to the promoter of BcSOC1 and repress its transcription, and BcCCA1 can form a complex with BcFLC to enhance the transcriptional inhibition of BcSOC1 by BcFLC. This study reveals a new mechanism by which the circadian clock regulates flowering time.

GhSWEET42 Regulates Flowering Time under Long-Day Conditions in Arabidopsis thaliana.

Flowering in plants is pivotal for initiating and advancing reproductive processes, impacting regional adaptation and crop yield. Despite numerous cloned and identified flowering time genes, research in cotton remains sparse. This study identified GhSWEET42 as a key determinant of the flowering time in cotton, demonstrating that its heterologous expression in Arabidopsis accelerated flowering under LD conditions compared to WT. Transgenic plants exhibited upregulated expression of the flowering inducers AtFT, AtSOC1, AtGI, and AtFKF1, alongside downregulated expression of the repressors AtTSF, AtFLC, and AtRGL2, correlating with the earlier flowering phenotype. GhSWEET42 showed a constitutive expression pattern, with elevated levels in the leaves, petals, and flower buds, and was notably higher in early-maturing cotton varieties. Subcellular localization assays confirmed GhSWEET42's presence on the cell membrane. Transcriptome analysis between WT and GhSWEET42-overexpressing Arabidopsis plants revealed 2393 differentially expressed genes (DEGs), spanning 221 biological processes, 93 molecular functions, and 37 cellular components according to Gene Ontology (GO) enrichment analysis. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis categorized the DEGs into metabolism and environmental information processing. These findings enhance the understanding of GhSWEET42's function and provide a foundation for elucidating the molecular mechanisms governing flowering time regulation in cotton.

Эколого-биологическая характеристика медоносных растений Удмуртской Республики

Abstract. The purpose is to analyze honey–bearing resources, biological forms and species diversity of natural, cultural and adventitious honey-bearing flora in the territory of the Udmurt Republic to create a scheme-map of the honey conveyor. Methods. In the study of this issue “Methods of conducting research in beekeeping” (2003), “Plant determinant of Udmurtia” were used. Results. As of January 1, 2023, the area of agricultural land in all land categories amounted to 1838.3 thousand ha, or 43.7 %, non-gricultural land – 2367.8 thousand hectares, or 56.3 % of the total land fund of the Udmurt Republic. The area of coniferous plants has increased by an average of 38 % since 1966, and hardwood by 35 %. The dynamics of the increase in areas for many species is positive – pine, spruce, ash, elm, alder, linden, willows. The life forms of honey plants of the republic have a different ratio: the largest number of 73 species are grasses (65.2 %), 29 are trees (25.8 %) and 10 are shrubs (9 %). When analyzing data on the flowering of honey plants in Udmurtia, most plants bloom in the off-season – 72.5 %, 25.8 % – in summer, spring. There are plants of prolonged flowering, and honey plants that bloom only in September are absent. The main honey-bearing crop is small-leaved linden. It has a large honey reserve; its specific weight of honey reserve is 90.92 %. To develop the honey reserve of the Udmurt Republic, it is necessary to have a number of bee colonies 4.5 times higher than the current level, which is 224.75 thousand bee colonies. Scientific novelty. Beekeeping in the Udmurt Republic is a promising area of agriculture in the development of forest and agricultural lands, the possibility of improving it and using the export of bees to the honey harvest, taking into account the flowering time of honeybees of natural and agricultural honeybees and active nomads.

Variation in plant cover and flower production of Carex rostrata and C. vesicaria within a freshwater littoral zone. A 14-year time course

Variation in plant cover and flower production of Carex rostrata and C. vesicaria within a freshwater littoral zone. A 14-year time course

H3K36 methyltransferase GhKMT3;1a and GhKMT3;2a promote flowering in upland cotton

BackgroundThe SET domain group (SDG) genes encode histone lysine methyltransferases, which regulate gene transcription by altering chromatin structure and play pivotal roles in plant flowering determination. However, few studies have investigated their role in the regulation of flowering in upland cotton.ResultsA total of 86 SDG genes were identified through genome-wide analysis in upland cotton (Gossypium hirsutum). These genes were unevenly distributed across 25 chromosomes. Cluster analysis revealed that the 86 GhSDGs were divided into seven main branches. RNA-seq data and qRT‒PCR analysis revealed that lysine methyltransferase 3 (KMT3) genes were expressed at high levels in stamens, pistils and other floral organs. Using virus-induced gene silencing (VIGS), functional characterization of GhKMT3;1a and GhKMT3;2a revealed that, compared with those of the controls, the GhKMT3;1a- and GhKMT3;2a-silenced plants exhibited later budding and flowering and lower plant heightwere shorter. In addition, the expression of flowering-related genes (GhAP1, GhSOC1 and GhFT) significantly decreased and the expression level of GhSVP significantly increased in the GhKMT3;1a- and GhKMT3;2a-silenced plants compared with the control plants.ConclusionA total of 86 SDG genes were identified in upland cotton, among which GhKMT3;1a and GhKMT3;2a might regulate flowering by affecting the expression of GhAP1, GhSOC1, GhFT and GhSVP. These findings will provide genetic resources for advanced molecular breeding in the future.

Sexual dimorphism and pollination mechanism of Zanthoxylum armatum, a vulnerable medicinally important dioecious tree

Among dioecious species, the differential strategy of resource allocation between male and female plants is depicted in their life-history traits and reproductive features. This is classified as sexual dimorphism. The strategies of resource allocation along with the habitat of these species pose an impact on their pollination mechanism and reproductive success. Zanthoxylum armatum DC (Rutaceae) is a small tree with wide economic and medicinal value. The species is naturally distributed in tropical parts of India and other countries. Due to overexploitation of natural populations in India, the species is rapidly declining. To restore the population of the species in the wild and establish commercial plantations, detailed knowledge of its reproductive biology is essential. Thus, the present study was conducted in natural population of Z. armatum growing in the union territory of Jammu and Kashmir, India. The study revealed sex-biased allocation and sexual dimorphism both in vegetative and reproductive traits. Such traits include more height and higher number of shoots, inflorescences, and flowers in male plants than in female plants. The natural populations of Z. armatum exhibit a male-biased sex ratio, and such biasness appears to be the outcome of resource allocation strategies and other demographic characteristics. Species possibly exhibit presence of ambophilous suite, i.e., a combination of wind and insect pollination in floral features. However, pollen dispersal by wind is up to limited distance, and thus wind may or may not be effective in fruit-set.

Blooming Business: How Consumer Satisfaction Shapes Online Plant and Cut Flower Spending

Online sales of plants are relatively new compared with other products. An online survey was used to measure online and in-store plant/flower spending from 1290 participants. Participants were satisfied with their online plant/flower purchases and spent $31.86 more on plants/flowers through online retailers than in stores. Participants’ social media use increased their in-store plant/flower spending but not online spending. Using Amazon, Google, and farm-direct online retailers increased both in-store and online plant/flower spending. Demographic characteristics did not influence online or in-store spending, except income which had a positive effect.

Ignoring within‐flower self‐fertilization and inbreeding depression biases estimates of selection on floral traits in a perennial alpine herb

Abstract Within‐flower self‐pollination should be the major source of self‐fertilization in mixed‐mating species that present single or few flowers simultaneously. It is also an often unmeasured source of selfing in species with many flowers open simultaneously. In self‐compatible species in which pistil and stamen numbers vary, the rate of within‐flower selfing should depend on the number of pistils and stamens, the timing of flowering and the morphology of subsidiary floral traits. The intensity and direction of selection on these traits should thus also depend on the level of inbreeding depression. Here, we measured the dependence of the within‐flower selfing rate on floral sex allocation, phenology, petal length and floral stalk height in a population of the perennial herb Pulsatilla alpina (Ranunculaceae) in which most individuals had single flowers. We estimated inbreeding depression in the population by comparing inbreeding coefficients between parents and seed progeny using microsatellite markers. We then estimated selection on the measured traits via female reproductive success at the flower level and compared our estimates with a hypothetical scenario in which inbreeding depression was assumed to be absent. Inbreeding depression was estimated to be severe (0.95). The within‐flower selfing rate varied widely among flowers and depended positively on stamen number and negatively on pistil number and flowering date, supporting the predictions of a mass‐action model. The dependence of the selfing rate on the measured floral traits consistently predicted (non‐linear) patterns of selection under high inbreeding depression that were distinct from those under a hypothetical scenario of no inbreeding depression. Synthesis. While previous research has emphasized the importance of mass‐action mating on selfing among flowers of plants with large floral displays, our results demonstrate its importance for selfing within individual flowers. They also demonstrate the importance of accounting for both the selfing rate and inbreeding depression when inferring selection on floral and other traits via female fitness.

Floral freezing tolerance is tied to flowering time in North American woody plant species.

As winter and spring temperatures continue to increase, the timing of flowering and leaf out is advancing in many seasonally cold regions. This advancement could put plants that flower early in the spring at risk of decreased reproduction in years when there are late freeze events. Unfortunately, relatively little is known about floral freezing tolerance in forest communities. In this study, we examined the impact of freezing temperatures on the flowers of woody plants in a region where there is rapid winter warming in North America. We subjected the flowers of twenty-five woody species to a hard (-5ºC) and a light freeze (0ºC). We assessed tissue damage using electrolyte leakage. In a subset of species, we also examined the impact of a hard freeze on pollen tube growth. To determine if the vulnerability of flowers to freezing damage relates to flowering time and to examine the responsiveness of flowering time to spring temperature, we recorded the date of first flower for our study species for three years. Across species, we found that floral freezing tolerance was strongly tied to flowering time with the highest freezing tolerance occurring in plants that bloomed earlier in the year. We hypothesize that these early blooming species are unlikely to be impacted by a false spring. Instead, the most vulnerable species to a false spring should be those that bloom later in the season. The flowering time in these species is also more sensitive to temperature, putting them at a great risk of experiencing a false spring. Ultimately, floral damage in one year will not have a large impact on species fitness, but if false springs become more frequent, there could be long-term impacts on reproduction of vulnerable species.

Regulatory Networks Underlying Plant Responses and Adaptation to Cold Stress.

Cold is a key determinant for plant growth and flowering time as well as an important environmental factor limiting plant growth and development. Recent studies have revealed the complex regulatory networks associated with plant responses to cold and identified their interconnections with signaling pathways related to light, the circadian clock, plant hormones, and pathogen defense. In this article, we review recent advances in understanding the molecular basis of cold perception and signal transduction pathways. We also summarize recent developments in the study of cold-responsive growth and flowering. Finally, we propose future directions for the study of long-term cold sensing, RNA secondary structures in response to cold, and the development of cold-tolerant and high-yield crops.

High expression of ethylene response factor BcERF98 delays the flowering time of non-heading Chinese cabbage.

BcERF98 is induced by ethylene signaling and inhibits the expression of BcFT by interacting with BcNF-YA2 and BcEIP9, thereby inhibiting plant flowering. Several stresses trigger the accumulation of ethylene, which then transmits the signal to ethylene response factors (ERFs) to participate in the regulation of plant development to adapt to the environment. This study clarifies the function of BcERF98, a homolog of AtERF98, in the regulation of plant flowering time mediated by high concentrations of ethylene. Results indicate that BcERF98 is a nuclear and the cell membrane-localized transcription factor and highly responsive to ethylene signaling. BcERF98 inhibits the expression of BcFT by interacting with BcEIP9 and BcNF-YA2, which are related to flowering time regulation, thereby participating in ethylene-mediated plant late flowering regulation. The results have enriched the theoretical knowledge of flowering regulation in non-heading Chinese cabbage (NHCC), providing the scientific basis and gene reserves for cultivating new varieties of NHCC with different flowering times.

Identification of Apple Flower Development-Related Gene Families and Analysis of Transcriptional Regulation.

Apple (Malus domestica Borkh.) stands out as a globally significant fruit tree with considerable economic importance. Nonetheless, the orchard production of 'Fuji' apples faces significant challenges, including delayed flowering in young trees and inconsistent annual yields in mature trees, ultimately resulting in suboptimal fruit yield due to insufficient flower bud formation. Flower development represents a pivotal process influencing plant adaptation to environmental conditions and is a crucial determinant of successful plant reproduction. The three gene or transcription factor (TF) families, C2H2, DELLA, and FKF1, have emerged as key regulators in plant flowering regulation; however, understanding their roles during apple flowering remains limited. Consequently, this study identified 24 MdC2H2, 6 MdDELLA, and 6 MdFKF1 genes in the apple genome with high confidence. Through phylogenetic analyses, the genes within each family were categorized into three distinct subgroups, with all facets of protein physicochemical properties and conserved motifs contingent upon subgroup classification. Repetitive events between these three gene families within the apple genome were elucidated via collinearity analysis. qRT-PCR analysis was conducted and revealed significant expression differences among MdC2H2-18, MdDELLA1, and MdFKF1-4 during apple bud development. Furthermore, yeast two-hybrid analysis unveiled an interaction between MdC2H2-18 and MdDELLA1. The genome-wide identification of the C2H2, DELLA, and FKF1 gene families in apples has shed light on the molecular mechanisms underlying apple flower bud development.

DNA Methylation of the Autonomous Pathway Is Associated with Flowering Time Variations in Arabidopsis thaliana.

Plant flowering time is affected by endogenous and exogenous factors, but its variation patterns among different populations of a species has not been fully established. In this study, 27 Arabidopsis thaliana accessions were used to investigate the relationship between autonomous pathway gene methylation, gene expression and flowering time variation. DNA methylation analysis, RT-qPCR and transgenic verification showed that variation in the flowering time among the Arabidopsis populations ranged from 19 to 55 days and was significantly correlated with methylation of the coding regions of six upstream genes in the autonomous pathway, FLOWERING LOCUS VE (FVE), FLOWERING LOCUS Y (FY), FLOWERING LOCUS D (FLD), PEPPER (PEP), HISTONE DEACETYLASE 5 (HAD5) and Pre-mRNA Processing Protein 39-1 (PRP39-1), as well as their relative expression levels. The expression of FVE and FVE(CS) was modified separately through degenerate codon substitution of cytosine and led to earlier flowering of transgenic plants by 8 days and 25 days, respectively. An accurate determination of methylated sites in FVE and FVE(CS) among those transgenic plants and the recipient Col-0 verified the close relationship between the number of methylation sites, expression and flowering time. Our findings suggest that the methylation variation of these six key upstream transcription factors was associated with the gene expression level of the autonomous pathway and flowering time in Arabidopsis. The FVE(CS) and FVE genes in transgenic plants tended to be hypermethylated, which could be a protective mechanism for plants. However, modification of gene sequences through degenerate codon substitution to reduce cytosine can avoid hypermethylated transferred genes in transgenic plants. It may be possible to partially regulate the flowering of plants by modified trans-epigenetic technology.

In vitro plant regeneration, flowering and fruiting of Solanum nigrum L. and its acclimatization for field transfer

In vitro plant regeneration, flowering and fruiting of Solanum nigrum L. and its acclimatization for field transfer

Field evaluation of biostimulants on growth, flowering, yield, and quality of snap beans in subtropical environment

The cultivation of snap beans (Phaseolus vulgaris L.) in subtropical regions faces environmental challenges leading to potential declines in yield. This study explores the efficacy of biostimulants as a solution, specifically investigating spraying treatments with 6-benzylaminopurine (6-BA), chitosan (Ch), triacontanol (TRIA), and potassium silicate (KSi) on the snap bean cv. Paulista. Over two growing seasons with late sowing and elevated summer temperatures, the research assesses growth, flowering, yield, and quality. Notably, 5 ppm TRIA demonstrates the most significant impact on plant growth and leaf nutrient content. Treatments with 40 ppm 6-BA, 5 ppm TRIA, or 200 ppm KSi exhibit notable effects on inflorescence flower count and flowers per plant. These treatments prove most effective for crucial green pod yield measures, including the number and weight of marketable pods. Moreover, 40 ppm 6-BA or 5 ppm TRIA significantly enhances pod characteristics, such as length, diameter, and weight, consistently improving over both seasons. Particularly, 5 ppm TRIA outperforms in enhancing the chemical quality of pods throughout the study. Overall, the findings suggest that the application of 5 ppm TRIA offers the most favorable enhancements for the growth, flowering, productivity, and quality of snap bean plants in subtropical field conditions.

Influence of plant community on Aedes albopictus (Diptera, Culicidae) oviposition behaviour: Insights from a Spanish botanical garden

Mosquitoes are capable of transmitting pathogens of both medical and veterinary significance. Addressing the nuisance and vector roles of Aedes albopictus through surveillance and control programs is a primary concern for European countries. Botanical gardens provide suitable habitats for the development of Ae. albopictus and represent typical points of entry of invasive species. To assess the oviposition preferences alongside various biotic parameters (plant species community, shade index, and flowering), we conducted a study in a botanical garden of Sóller (Mallorca, Balearic Islands, Spain). A total of 6,368 Ae. albopictus eggs were recorded in 36 ovitraps positioned and revised every 15 days in seven different habitats over six months in 2016. Zero-inflated and generalized linear mixed-effects models were used to analyse Ae. albopictus habitat preferences. The number of eggs increased throughout the sampling period, peaking in September. The oviposition rates showed a patchy distribution, with Ae. albopictus showing preference for oviposition in laurel forest and cropland habitats. A positive effect of large leaves and presence of flowers on the oviposition of Ae. albopictus were also recorded. This study provides valuable information into the behaviour of Ae. albopictus in botanical gardens, which is essential data for informing surveillance and control programs.