Flower Bud Differentiation Research Articles

High-temperature stress in strawberry: understanding physiological, biochemical and molecular responses.

Heat stress reduces strawberry growth and fruit quality by impairing photosynthesis, disrupting hormone regulation, and altering mineral nutrition. Multi-omics studies show extensive transcriptional, post-transcriptional, proteomic and metabolomic under high temperatures. Garden strawberry is a globally cultivated, economically important fruit crop highly susceptible to episodic heat waves and chronically rising temperatures associated with climate change. Heat stress negatively affects the growth, development, and quality of strawberries. Elevated temperatures affect photosynthesis, respiration, water balance, hormone signaling, and carbohydrate metabolism in strawberries. Heat stress reduces the size and number of leaves, the number of crowns, the differentiation of flower buds, and the viability of pollen and fruit set, ultimately leading to a lower yield. On a physiological level, heat stress reduces membrane stability, increases the production of reactive oxygen species, and reduces the antioxidant capacity of strawberries. Heat-tolerant varieties have better physiological and biochemical adaptation mechanisms compared to heat-sensitive varieties. Breeding heat-tolerant strawberry cultivars involves selection for traits such as increased leaf temperature, membrane thermostability, and chlorophyll content. Multi-omics studies show extensive transcriptional, post-transcriptional, proteomic, metabolomic, and ionomic reprogramming at high temperatures. Integrative-omics approaches combine multiple omics datasets to obtain a systemic understanding of the responses to heat stress in strawberries. This article summarizes the deciphering of strawberry responses to heat stress using physiological, biochemical, and molecular approaches that will enable the development of resilient adaptation strategies that sustain strawberry production under global climate change.

Responses of Growth, Enzyme Activity, and Flower Bud Differentiation of Pepper Seedlings to Nitrogen Concentration at Different Growth Stages

The concentration of nitrogen fertilizer is matched with the nutrient requirements in different growth stages of plants, which coordinates their vegetative and reproductive growth. In this study, the influences of nitrogen concentration before and after initiation of flower bud differentiation (first and second stage, respectively) on pepper seedling quality were studied. The chlorophyll a content, sucrose synthase activity, and sucrose phosphate synthase activity of pepper seedlings grown under moderate nitrogen (15 mmol L−1) in the first stage combined with high nitrogen (25.61 mmol L−1) in the second stage were 15.7%, 39.3%, and 34.6% higher than those of the same nitrogen concentration (15 mmol L−1) in the first and second stages treatment, respectively. The regression model also showed that the values of flower bud diameter, shoot fresh weight, root fresh weight, and glutamine synthetase activity of pepper were high under the condition of moderate nitrogen in the first stage and higher nitrogen in the second stage. In addition, the results of comprehensive evaluation showed that moderate nitrogen (15 mmol L−1) in the first stage and high nitrogen (25.61 mmol L−1) in the second stage treatment ranked first, which improved carbon and nitrogen metabolism, increased biomass accumulation, and promoted the flower bud differentiation and flowering of pepper seedlings.

CpSPL10-CpELF4 module involves in the negative regulation of flower bud differentiation in Chinese cherry

SQUAMOSA promoter-binding protein-like (SPL) genes play a crucial role in regulating floral induction. Despite such importance, a comprehensive study of SPLs in Chinese cherry flower bud development has been absent. In this study, 32 CpSPL genes were identified. According to expression profiling, CpSPLs exhibited tissue-specific expression and distinct trends throughout flower bud differentiation. Specifically, CpSPL10 was greatly expressed at the beginning of the differentiation, and its role was further investigated. Its overexpression extended the vegetative growth of transgenic tobacco plants, delayed flowering by about 20 days. Moreover, the accumulation of NbELF4 (Early flowering 4) transcripts was enhanced due to the up-regulated levels of CpSPL10 in tobacco plants. ELF4 functions as a major element of the circadian clock; its high expression typically delays the transition from vegetative-to-reproductive growth. Further experiments revealed that CpSPL10 interacts with CpSPL9 or a transposase-derived transcription factor CpFRS5 (FAR1-RELATED SEQUENCE 5) and activates the expression of the downstream gene CpELF4. Notably, the GUS fusing reporter assay detected the activation of CpSPL10 and CpELF4 promoters in shoot apical meristems of transgenic Arabidopsis. These findings revealed the negative regulation of the CpSPL10-CpELF4 module in flower bud differentiation, providing references for supplementing the specific relationships among SPL, FRS, and ELF4.

Targeted Metabolites and Transcriptome Analysis Uncover the Putative Role of Auxin in Floral Sex Determination in Litchi chinensis Sonn.

Litchi exhibits a large number of flowers, many flowering batches, and an inconsistent ratio of male and female flowers, frequently leading to a low fruit-setting rate. Floral sexual differentiation is a crucial phase in perennial trees to ensure optimal fruit production. However, the mechanism behind floral differentiation remains unclear. The objective of the study was to identify the role of auxin in floral differentiation at the transcriptional level. The results showed that the ratio of female flowers treated with naphthalene acetic acid (NAA) was significantly lower than that of the control stage (M0/F0). The levels of endogenous auxin and auxin metabolites were measured in male and female flowers at different stages of development. It was found that the levels of IAA, IAA-Glu, IAA-Asp, and IAA-Ala were significantly higher in male flowers compared to female flowers. Next-generation sequencing and modeling were employed to perform an in-depth transcriptome analysis on all flower buds in litchi 'Feizixiao' cultivars (Litchi chinensis Sonn.). Plant hormones were found to exert a significant impact on the litchi flowering process and flower proliferation. Specifically, a majority of differentially expressed genes (DEGs) related to the auxin pathway were noticeably increased during male flower bud differentiation. The current findings will enhance our comprehension of the process and control mechanism of litchi floral sexual differentiation. It also offers a theoretical foundation for implementing strategies to regulate flowering and enhance fruit production in litchi cultivation.

Effect of low sunlight and high temperature during flower bud differentiation on the cut flower quality of carnation ‘Cherry Tessino’

Effect of low sunlight and high temperature during flower bud differentiation on the cut flower quality of carnation ‘Cherry Tessino’

The effector SJP3 interferes with pistil development by sustaining SHORT VEGETATIVE PHASE 3 expression in jujube.

Jujube witches' broom (JWB) is a phytoplasma disease that causes severe damage to jujube (Ziziphus jujuba) crops worldwide. Diseased jujube plants show enhanced vegetative growth after floral reversion, including leafy flower structures (phyllody) and the fourth whorl converting into a vegetative shoot. In previous research, secreted JWB protein 3 (SJP3) was identified as an inducer of phyllody. However, the molecular mechanisms of SJP3-mediated pistil reversion remain unknown. Here, the effector SJP3 was found to interact with the MADS-box protein SHORT VEGETATIVE PHASE 3 (ZjSVP3). ZjSVP3 was expressed in young leaves and during the initial flower bud differentiation of healthy jujube-bearing shoots but was constitutively expressed in JWB phytoplasma-infected flowers until the later stage of floral development. The SJP3 effector showed the same expression pattern in the diseased buds and promoted ZjSVP3 accumulation in SJP3 transgenic jujube calli. The N-terminal domains of ZjSVP3 contributed to its escape from protein degradation in the presence of SJP3. Heterologous expression of ZjSVP3 in Nicotiana benthamiana produced typical pistil abnormalities, including trichome-enriched style and stem-like structures within the leaf-like ovary, which were consistent with those in the mildly malformed lines overexpressing SJP3. Furthermore, ectopic expression of ZjSVP3 directly bound to the zinc finger protein 8 (ZjZFP8) and MADS-box gene SHATTERPROOF 1 (ZjSHP1) promoters to regulate their expression, resulting in abnormal pistil development. Overall, effector SJP3-mediated derepression of ZjSVP3 sustained its expression to interfere with pistil development, providing insight into the mechanisms of pistil reversion caused by JWB phytoplasma in specific perennial woody plant species.

Possible Mechanism of Sucrose and Trehalose-6-Phosphate in Regulating the Secondary Flower on the Strong Upright Spring Shoots of Blueberry Planted in Greenhouse.

Secondary flowering is the phenomenon in which a tree blooms twice or more times a year. Along with the development of blueberry (Vaccinium corymbosum L.) fruits in spring, a large number of secondary flowers on the strong upright spring shoots were noticed in blueberries planted in the greenhouse. To reveal the cause and possible regulatory mechanism of the phenomenon, we clarified the phenological characteristics of flower bud differentiation and development on the spring shoots by combining phenological phenotype with anatomical observation. Furthermore, the changes in carbohydrates, trehalose-6-phosphate (Tre6P), and the relationship among the key enzyme regulatory genes for Tre6P metabolism and the key regulatory genes for flower formation during the differentiation process of apical buds and axillary buds were investigated. The results showed that the process of flower bud differentiation and flowering of apical and axillary buds was consistent, accompanied by a large amount of carbohydrate consumption. This process was positively correlated with the expression trends of VcTPS1/2, VcSnRK1, VcFT, VcLFY2, VcSPL43, VcAP1, and VcDAM in general, and negatively correlated with that of VcTPP. In addition, there is a certain difference in the differentiation progress of flower buds between the apical and axillary buds. Compared with axillary buds, apical buds had higher contents of sucrose, fructose, glucose, Tre6P, and higher expression levels of VcTPS2, VcFT, VcSPL43, and VcAP1. Moreover, VcTPS1 and VcTPS2 were more closely related to the physiological substances (sucrose and Tre6P) in axillary bud and apical bud differentiation, respectively. It was suggested that sucrose and trehalose-6-phosphate play a crucial role in promoting flower bud differentiation in strong upright spring shoots, and VcTPS1 and VcTPS2 might play a central role in these activities. Our study provided substantial sight for further study on the mechanism of multiple flowering of blueberries and laid a foundation for the regulation and utilization of the phenomenon of multiple flowering in a growing season of perennial woody plants.

Morphological and physiological investigations reveal the regulatory effect of exogenous paclobutrazol on flowering promotion by winter warming in Chaenomeles speciosa ‘Changshouguan’

The application of exogenous paclobutrazol (PP333) can improve the ability of winter warming to promote flowering in Chaenomeles speciosa, but the underlying mechanism is unclear. In this study, the cultivar ‘Changshouguan’ was sprayed with different concentrations of PP333 during flower bud differentiation, and the changes in the anatomical structures and physiological characteristics of the flower buds during the differentiation process, as well as the growth state of the flower buds and the effect on flowering promotion after winter warming treatment, were comprehensively investigated. The results showed that different concentrations of PP333 could advance the flowering time of ‘Changshouguan’ by 15–24 d under the warming treatment and increase the flowering duration to 17 d compared with those under the warming treatment alone (CK), and 1000 mg/L was the best treatment. Compared with the CK treatment, the PP333 treatment decreased the contents of indole acetic acid (IAA) and gibberellic acid (GAs) and increased the contents of zeatin ribosides (ZRs) and abscisic acid (ABA), thus changing the balance of hormones during flower bud differentiation. The inflection point (low point) of the curve shapes of the ZRs/GAs and ZRs/IAA ratios appeared significantly earlier, which showed a pattern consistent with soluble sugar and protein content and antioxidant activity. Interestingly, the above changes also corresponded to earlier flowering times during the warming process. Taken together, these results indicate that spraying an appropriate concentration of PP333 in the early stage of ‘Changshouguan’ flower bud differentiation promotes the early differentiation of flower buds and early flowering under winter warming treatment by altering their endogenous hormone content and homeostasis and changing their physiological state. The key to maintaining a relatively long flowering period in plants in the PP333 treatment group after flowering promotion was the increased accumulation of sugars and proteins.

Genome-Wide Identification and Expression Analysis of the Sweet Cherry Whirly Gene Family.

Sweet cherry (Prunus avium) is one of the economically valuable horticultural fruit trees and it is widely cultivated throughout the world. Whirly (WHY) genes are a unique gene family with few members and have important biological functions in plant growth, development, and response to abiotic stress. This study utilized whole-genome identification to conduct a comprehensive analysis of the WHY genes in sweet cherry and examined their transcription levels in different tissues and under abiotic stress to explore their functions. Two WHY genes were identified in the sweet cherry genome and named PavWHY1 and PavWHY2, respectively, based on their homology with those in Arabidopsis thaliana. Both genes have theoretical isoelectric points greater than seven and are hydrophilic proteins, suggesting that they may be localized in plastids. The two genes are evolutionarily classified into two categories, with large differences in gene structure, and highly similar protein tertiary structures, and both have conserved domains of WHY. PavWHY1 and PavWHY2 are collinear with AtWHY1 and AtWHY2, respectively. The promoter sequence contains cis-acting elements related to hormones and abiotic stress, which are differentially expressed during flower bud differentiation, fruit development, and cold accumulation. qRT-PCR showed that PavWHY1 and PavWHY2 were differentially expressed in flower and fruit development and responded to low temperature and exogenous ABA treatment. The recombinant plasmid pGreenII-0800-Luc with the promoters of these two genes can activate luciferase expression in tobacco. Protein interaction predictions indicate that these gene products may interact with other proteins. This study reveals the molecular features, evolutionary relationships, and expression patterns of sweet cherry WHY genes, and investigates the activities of their promoters, which lays the foundation for further exploration of their biological functions and provides new insights into the WHY gene family in Rosaceae.

Comparative Proteomic Analysis of Floral Buds before and after Opening in Walnut (Juglans regia L.).

The walnut (Juglans regia L.) is a typical and an economically important tree species for nut production with heterodichogamy. The absence of female and male flowering periods seriously affects both the pollination and fruit setting rates of walnuts, thereby affecting the yield and quality. Therefore, studying the characteristics and processes of flower bud differentiation helps in gaining a deeper understanding of the regularity of the mechanism of heterodichogamy in walnuts. In this study, a total of 3540 proteins were detected in walnut and 885 unique differentially expressed proteins (DEPs) were identified using the isobaric tags for the relative and absolute quantitation (iTRAQ)-labeling method. Among all DEPs, 12 common proteins were detected in all four of the obtained contrasts. GO and KEGG analyses of 12 common DEPs showed that their functions are distributed in the cytoplasm metabolic pathways, photosynthesis, glyoxylate and dicarboxylate metabolism, and the biosynthesis of secondary metabolites, which are involved in energy production and conversion, synthesis, and the breakdown of proteomes. In addition, a function analysis was performed, whereby the DEPs were classified as involved in photosynthesis, morphogenesis, metabolism, or the stress response. A total of eight proteins were identified as associated with the morphogenesis of stamen development, such as stamen-specific protein FIL1-like (XP_018830780.1), putative leucine-rich repeat receptor-like serine/threonine-protein kinase At2g24130 (XP_018822513.1), cytochrome P450 704B1-like isoform X2 (XP_018845266.1), ervatamin-B-like (XP_018824181.1), probable glucan endo-1,3-beta-glucosidase A6 (XP_018844051.1), pathogenesis-related protein 5-like (XP_018835774.1), GDSL esterase/lipase At5g22810-like (XP_018833146.1), and fatty acyl-CoA reductase 2 (XP_018848853.1). Our results predict several crucial proteins and deepen the understanding of the biochemical mechanism that regulates the formation of male and female flower buds in walnuts.

Morphogenesis, megagametogenesis, and microgametogenesis in Actinidia arguta flower buds

In dioecious plants, understanding sexual differentiation is important for improving cultivation techniques. Flower bud morphogenesis and gametophyte formation underlie the mechanism of sexual differentiation. Actinidia arguta (hardy kiwi) is a unisexual plant, and there have been few studies on its flower bud differentiation or gametophyte formation. We studied flower bud morphogenesis and gametophyte formation in A. arguta using paraffin sections and found that the morphogenesis of male and female flower buds was divided into six stages: the undifferentiated stage, inflorescence initials differentiation stage, calyx primordium differentiation stage, petal primordium differentiation stage, stamen primordium differentiation stage, and pistil primordium differentiation stage. Morphogenesis in the male inflorescence can reach quaternary flower primordia, and morphogenesis in the female inflorescence can reach the tertiary flower primordia, however, no Stage 4 lateral flowers in the male inflorescence or Stage 3 lateral flowers in the female inflorescence were found in natural situation. The embryo sac in female plants was a monocellular Polygonum type, and the embryo sac development in male plants was incomplete; abortion occurred before the archesporial cells developed. The male gametophyte differentiation process in the male plant was normal, with pollen grains similar in shape to a rugby ball and arranged neatly in the anther. The pollen grain differentiation in female plants was abnormal; abortion occurred at the uninucleate microspore stage, and mature pollen grains were irregularly spherical.

Screening of flower bud differentiation conditions and changes in metabolite content of Phalaenopsis pulcherrima

Using the Phalaenopsis pulcherrima (P. pulcherrima) as the test material, the optimal conditions for flower bud differentiation were selected by setting different photoperiods and temperatures. The process of flower bud differentiation was observed, and changes in the content of carbohydrates, hormones, and other metabolites during flower bud differentiation were studied. The results showed that the optimum time of illumination was 16 h. d−1 and the temperature was 30 ℃ / 25 ℃. According to the characteristics of the flower bud development of P. pulcherrima, the differentiation process can be divided into six periods: the initial differentiation phase, inflorescence primordium differentiation phase, flower primordium differentiation phase, sepal primordium differentiation phase, petal primordium differentiation phase, and column and pollinia differentiation phase. The soluble sugar content in the leaves showed a trend of first increasing and then decreasing. The soluble sugar content was highest 30 days after the treatment, when the differentiation of the inflorescence primordium was completed. The starch content first decreased, then increased, and finally decreased. The starch content was lowest at 30 days of treatment and highest at 35 days. The soluble protein content in the leaves reached a maximum after 30 days of treatment. With the continuous differentiation of flower buds, the soluble protein content showed an overall decreasing trend. The zeatin (ZT) content reached a maximum at day 35, showing an overall decreasing trend from days 35 to 50 and reaching a minimum at day 50. The gibberellin (GA3) and auxin (IAA) content first decreased and then increased during the process of flower bud differentiation. The changes in soluble sugar and soluble protein content during flower bud differentiation are consistent, while the changes in GA3 and IAA are consistent.

Endophytic Microorganisms in Tomato Roots, Changes in the Structure and Function of the Community at Different Growing Stages.

This study analyzed flower bud differentiation and fruiting stages to investigate how the structure of the plant endophytic microbial community in the roots of tomatoes changes with plant senescence. Based on high-throughput sequencing technology, the diversity and relative abundance of endophytic microorganisms (bacteria and fungi) in tomato stems at different growth stages were analyzed. At the same time, based on LEfSe analysis, the differences in endophytic microorganisms in tomato stems at different growth stages were studied. Based on PICRUSt2 function prediction and FUNGuild, we predicted the functions of endophytic bacterial and fungal communities in tomato stems at different growth stages to explore potential microbial functional traits. The results demonstrated that not only different unique bacterial genera but also unique fungal genera could be found colonizing tomato roots at different growth stages. In tomato seedlings, flower bud differentiation, and fruiting stages, the functions of colonizing endophytes in tomato roots could primarily contribute to the promotion of plant growth, stress resistance, and improvement in nutrient cycling, respectively. These results also suggest that different functional endophytes colonize tomato roots at different growth stages.

Morphological Study on the Differentiation of Flower Buds and the Embryological Stages of Male and Female Floral Organs in Lespedeza davurica (Laxm.) Schindl. cv. JinNong (Fabaceae).

Lespedeza davurica (Laxm.) is a leguminous plant with significant ecological benefits, but its embryonic development mechanism remains unclear. We investigated the flower bud differentiation, megaspore and microspore formation, gametophyte development, and embryo and endosperm development in L. davurica. Our aim was to elucidate the relationship between the external morphology and internal development processes of male and female floral organs during growth, as well as the reproductive factors influencing fruiting. The results indicated that although the pistil develops later than the stamen during flower bud differentiation, both organs mature synchronously before flowering. L. davurica pollen exhibits three germination grooves, a reticulate outer wall, and papillary structures on the anther surface. In vivo pollination experiments revealed abnormal spiral growth of L. davurica pollen tubes within the style and the occurrence of callus plugs, which may reduce the seed setting rate. The anther wall development follows the dicotyledonous type, with tetrads formed through microspore meiosis exhibiting both left-right symmetry and tetrahedral arrangements. L. davurica has a single ovule, and the embryo sac develops in the monosporic polygonum type. After dormancy, the zygote undergoes multiple divisions, progressing through spherical, heart-shaped, and torpedo-shaped embryo stages, culminating in a mature embryo. A mature seed comprises cotyledons, hypocotyl, embryo, radicle, and seed coat. Phylogenetic tree analysis reveals a close genetic relationship between L. davurica and other leguminous plants from the genera Lespedeza and Medicago. This study provides valuable insights into the regulation of flowering and hybrid breeding in leguminous plants and offers a new perspective on the development of floral organs and seed setting rates.

Genome-Wide Identification and Characterization of the GRAS Gene Family in Lettuce Revealed That Silencing LsGRAS13 Delayed Bolting.

Lettuce is susceptible to high-temperature stress during cultivation, leading to bolting and affecting yield. Plant-specific transcription factors, known as GRAS proteins, play a crucial role in regulating plant growth, development, and abiotic stress responses. In this study, the entire lettuce LsGRAS gene family was identified. The results show that 59 LsGRAS genes are unevenly distributed across the nine chromosomes. Additionally, all LsGRAS proteins showed 100% nuclear localization based on the predicted subcellular localization and were phylogenetically classified into nine conserved subfamilies. To investigate the expression profiles of these genes in lettuce, we analyzed the transcription levels of all 59 LsGRAS genes in the publicly available RNA-seq data under the high-temperature treatment conducted in the presence of exogenous melatonin. The findings indicate that the transcript levels of the LsGRAS13 gene were higher on days 6, 9, 15, 18, and 27 under the high-temperature (35/30 °C) treatment with melatonin than on the same treatment days without melatonin. The functional studies demonstrate that silencing LsGRAS13 accelerated bolting in lettuce. Furthermore, the paraffin sectioning results showed that flower bud differentiation in LsGRAS13-silenced plants occurred significantly faster than in control plants. In this study, the LsGRAS genes were annotated and analyzed, and the expression pattern of the LsGRAS gene following melatonin treatment under high-temperature conditions was explored. This exploration provides valuable information and identifies candidate genes associated with the response mechanism of lettuce plants high-temperature stress.

Improving mangoes' productivity and crop water productivity by 24-epibrassinosteroids and hydrogen peroxide under deficit irrigation

In nature, plants are frequently subjected to a wide range of abiotic stresses that drastically reduce crop productivity. Deficit in irrigation is one of the main factors of abiotic stresses that affect agricultural productivity. Nevertheless, not much research has been done on how to use water with brassinosteroids (Br) and hydrogen peroxide (H2O2)in deficit water conditions in order to reach comparatively good values of mango tree growth, productivity, and fruit quality as well as crop water productivity (WPC). A split-plot experiment in a complete randomized block system design study with 3 regulated deficit irrigation levels i.e. 100% IR (Irrigation requirement), 80% IR, and 60% IR was implemented in 2022 and 2023, each irrigation regime was combined with the foliar application of distilled water (control), 1 mg/L Br, 10 mM H2O2, 1 mg/L Br + 10 mM H2O2. Foliar treatments were applied at 3 different phenological stages: flower bud induction and differentiation, full bloom, and beginning of fruit set. The results showed that fruit shape index and acidity significantly improved as irrigation volume increased, however, the proportion of fruit mineral content and fruit chemical characteristics was inversely correlated with the volume of water. Meanwhile, moderate regular deficit irrigation (80% IR) achieved marked increases in leaf minerals and total chlorophyll content, fruit quality, yield, and water use efficiency. Drought stress (60% IR) significantly decreased fruit set, fruit retention, yield traits, and fruit physical and chemical properties, at the same time, significant improvements in the content of stress indicators (proline, total phenols, and carotenoids) were observed compared with control. All treatments with Br and H2O2 alone or in combination under drought stress had a pronounced effect in this regard. Overall, foliar spray of 1 mg/L Br+10 mM H2O2 was the most powerful treatment that emended the unpropitious effect of water stress.

Effect of Photoperiod Duration on Flower Bud Differentiation and Related Gene Expression in Bougainvillea glabra 'Sao Paulo'.

Environmental conditions, such as photoperiod, affect the developmental response of plants; thus, plants have evolved molecular mechanisms to adapt to changes in photoperiod. In Bougainvillea spp., the mechanism of flower formation underlying flowering control techniques remains poorly understood, and the physiological changes that occur during flower bud formation and the expression of related genes are not yet fully understood. In this study, we induced flowering of potted Bougainvillea glabra 'Sao Paulo' plants under light-control treatments and analyzed their effects on flowering time, number of flower buds, flowering quality, as well as quality of flower formation, which was analyzed using transcriptome sequencing. Light-control treatment effectively induced the rapid formation of flower buds and early flowering in B. glabra 'Sao Paulo', with the time of flower bud formation being 119 days earlier and the flowering period extended six days longer than those of the control plants. The light-control treatment caused the bracts to become smaller and lighter in color, while the number of flowers increased, and the neatness of flowering improved. Transcriptome sequencing of the apical buds identified 1235 differentially expressed genes (DEGs) related to the pathways of environmental adaptation, biosynthesis of other secondary metabolites, glycan biosynthesis and metabolism, and energy metabolism. DEGs related to gibberellin metabolism were analyzed, wherein five DEGs were identified between the control and treatment groups. Transcriptomic analysis revealed that the gibberellin regulatory pathway is linked to flowering. Specifically, GA and GID1 levels increased during this process, enhancing DELLA protein degradation. However, decreasing this protein's binding to CO did not halt FT upregulation, thereby advancing the flowering of B. glabra 'Sao Paulo'. The findings of our study have implications for future research on photoperiod and its role in controlling flowering timing of Bougainvillea spp.

Floral Initiation, Organogenesis, and Flowering of Mature Paphiopedilum Clair de Lune ‘Edgard Van Belle’ Award of Merit/American Orchid Society Plants Derived from Divisions

Paphiopedilum Clair de Lune ‘Edgard Van Belle’, an excellent Maudiae-type hybrid that has been propagated by artificial division for a long time. We studied its flower bud initiation, development of floral organs, and flowering habits with a view to providing information for flowering control and efficient commercial production. According to our research, the flower bud initiation phase of this cultivar begins in February every year, and 80% of the plants completed sepal primordium differentiation in March, The flower bud differentiation lasts for 6 to 7 months, until flowering in August. Within 1 to 3 months after flower bud differentiation, all tested plants differentiated lateral buds. After 5 to 6 months, the new, aboveground vegetative shoots reached their maximum growth, with an average plant height of 20 cm, five leaves, and a shoot dry weight of more than 3 g. From February to April of the following year, a new cycle of flower development and vegetative growth began. In addition, this cultivar was notably sensitivity to high ambient temperature during the late phase of flower development, with a flower bud drop rate as high as 33.3% under average day/night temperatures of 29.0/26.5 °C.

Impact of flowering temperature on litchi yield under climate change: A case study in Taiwan

Litchi is a subtropical fruit tree that undergoes flower bud differentiation under low-temperature conditions. However, climate change has affected litchi production in Taiwan, causing litchi farmers to experience economic losses. This study explored the influence of flowering temperature on litchi yield under climate change in Taiwan by analyzing litchi production data from 2001 to 2020 and observation data from meteorological stations in litchi-producing areas. Historical observed data were used to construct several regression models relating temperature to yield, with the performance of the models used to determine critical temperature thresholds for litchi flower bud differentiation. Analytical climate data (CMIP5) were used to project yield changes in Taiwan’s litchi-producing regions under anticipated low-temperature conditions for the mid- (2036–2065) and late- (2071–2100) 21st century. The variable that exhibited the highest correlation with yield changes was the number of days with an average flowering temperature below 16 °C. The production yield, in terms of yield variation per hectare, is expected to decrease by 12 % to 35 % by the end of the 21st century (2071–2100). Given the projected decline in the number of cooler days due to climate change, existing litchi cultivars may become unsuitable for cultivation in production areas in southern Taiwan. Practical ImplicationsSome fruit trees require a period of low temperature before their flowering stage. Climate change is expected to cause warming of winter temperatures in Taiwan, which is likely to lead to reduced litchi flowering. The current study assessed the potential effects of climate change on litchi flowering in the future.Historical observed data were used to establish models, and critical temperature thresholds for litchi flowering were determined on the basis of model performance. Days with average temperatures below 16 °C exhibited the highest correlation with litchi yield among the tested thresholds. According to our results, farmers can use this 16 °C threshold to evaluate the potential effects of future climate change at their current farm locations and to identify other areas with similar or more favorable conditions for litchi cultivation. For agricultural researchers, this temperature threshold could provide a target for new litchi variety breeding and a reference basis for research on optimal cultivation methods.Notably, because climate change projection data have a high degree of uncertainty, the results of this study may differ from those of studies using different databases. In this study, we used an ensemble of CMIP5 projections incorporating data from models from various research centers around the world, which can provide more robust results based on an ensemble mean than those obtainable from a single model or a few models. In addition, rainfall is a crucial factor during the flowering growth stage. Future studies should consider the effects of rainfall and temperature on yield and should consider using a model with yield being considered a function of both of these variables to improve model accuracy.To conclude, the present study provides researchers, policymakers, and other stakeholders with insights into the primary effects of climate change on litchi production. It also lays the groundwork for future climate adaptation strategies in Taiwan’s litchi industry.

Growth, antioxidant enzyme activity and transcriptome response to low-temperature induction of flowering in cultivated strawberry

This study is aimed to investigate the impact of low-temperature treatment on growth, antioxidant enzyme activity, flowering physiology and transcriptome change of the cultivated strawberry, cultivar 'Baiyu'. The runner plants were subjected to 16 ± 1 °C as low-temperature for 5, 10, and 15 days. By comparison with the plants just before treatment (at day 0), it was shown that during the 15-day low temperature treatment, plant height, leaf area, and dry weight significantly, amino acid and soluble sugar contents all decreased with concurrent calyx formation, while the levels of MDA, activities of SOD and CAT increased significantly. Flower bud differentiation began before day 5, as evidenced by significant upregulation in expression of several known flower -related genes including FaAP1, FaSVP, FaCO1, and FaLFY. Tissues from plants treated for 5d and 0d at 16 ± 1 °C were used for transcriptome analysis and the results showed that significant changes in more than 20,179 genes under low-temperature treatment, among which, the expression of genes in metabolic processes, catalytic activity and binding of the molecular function, signal transduction and encoding transcription factors were mostly affected.