Flower Buds Research Articles

Molecular mechanisms underlying floral fragrance in Camellia japonica ‘High Fragrance’: a time-course assessment

Camellia japonica ‘High Fragrance’ is a camellia hybrid known for its unique and intense floral scent. The current understanding of the dynamic changes in its fragrance and the underlying mechanisms are still limited. This study employed a combination of metabolomic and transcriptomic approaches to reveal the characteristics of the metabolites involved in the remarkable fragrance of this camellia and their biosynthetic mechanisms along three flower developmental stages (flower bud, initial bloom, and full bloom). Among the 349 detected volatile organic compounds (VOCs), the majority were terpenes (57, 16.33%) and esters (53, 15.19%). Of these, 136 VOCs exhibited differential accumulation over time. Transcriptomic data from floral organs at different flowering stages identified 56,303 genes, with 13,793 showing significant differential expression. KEGG enrichment analysis revealed 57, 91, and 33 candidate differential genes related to the biosynthesis of terpenes, phenylpropanoids, and fatty acid derivatives, respectively. This indicates that terpenes, esters, and their related synthetic genes might play a crucial role in the formation of ‘High Fragrance’ characteristics. During the entire flowering process, the majority of genes exhibited an elevated expression pattern, which correlated with the progressive accumulation of VOCs. Interestingly, the expression patterns of the differentially expressed genes in the mevalonate (MVA) and 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways, associated with terpene synthesis, showed opposite trends. A transcriptional-metabolic regulatory network linking terpenoid compounds, related synthetic enzymes, and potential transcription factors could be outlined for ‘High Fragrance’ camellia, thus providing a theoretical basis for further exploring these events and breeding more fragrant camellias.

Dry spells trigger durian flowering in aseasonal tropics

AbstractThe flowering period of durian is influenced by weather conditions such as prolonged drought and low temperatures. However, the specific criteria and durations of these conditions remain unclear. This study aimed to identify weather conditions that trigger durian flowering by monitoring its phenology and analyzing the relationship between minimum temperature and rainfall using two types of durian— grafting type and seed-grown type. Three flowering events were observed in 2022 and two in 2023. Considering there were no differences in the number or timing of flowering events among the two types, it suggests that genetic background differences do not influence flowering phenology. All flowering events were best explained using the 15-day moving average of rainfall, with the peak of the first flowering occurring approximately 50 days after the 15-day moving average of rainfall fell below 1 mm. These results suggest that drought accumulation over approximately 15 days may trigger the induction of durian flower buds. However, no correlation was determined between the minimum temperature and the first flowering date. These findings indicate that durian flowering is induced by milder drought conditions than those previously proposed. Differences in variety and climate may have led to results different from those reported in earlier studies. Long-term monitoring across multiple sites and varieties is required to discuss these differences further.

Unlocking the Potential of Shoot Tip Culture for Rapid Multiplication of Musa acuminata (AAA) cv. Amrit Sagar

Unlocking the Potential of Shoot Tip Culture for Rapid Multiplication of Musa acuminata (AAA) cv. Amrit Sagar

Vegetative and reproductive morphology of Othniophyton elongatum (MacGinitie) gen. et comb. nov., an extinct angiosperm of possible caryophyllalean affinity from the Eocene of Colorado and Utah, USA

Abstract Background and Aims Eocene foliage formerly attributed to the extant araliaceous genus Oreopanax was found attached to twigs bearing inflorescences and infructescences unlike those of Araliaceae. Using newly observable characters of phyllotaxy, vegetative and floral buds, infructescences and seeds, we sought to reassess the affinities of this strange angiosperm. Methods Fossils were studied from the Parachute Creek Member of the Green River Formation from near Bonanza, Utah and Douglas Pass, Colorado (ca. 47 Ma). Macrofossil impression remains were investigated by low angle reflected light and subtle details of the vegetative and floral buds, stamens, mature fruits, and seeds were revealed by optical shadow effect microscopy documenting previously obscure topographic surface features. Key Results Othniophyton elongatum (MacGinitie) Manchester, Judd, Correa-Narvaez gen. et comb. nov. has simple, short-petiolate, elongate, entire-margined leaves with thick midveins, pinnate, brochidodromous secondaries, common intersecondary veins and finely reticulate higher order venation. Inflorescences are small axillary cymes; flower buds are subglobose and pedicellate, in bract axils. The flowers are actinomorphic, bisexual, with ca. five imbricate perianth parts, ca. 24 stamens with elongate anthers and short filaments, arising from a hypanthium. The whorl of stamens persists to fruiting stage. The ovary is superior, with probable basal placentation and five stigmatic arms. Fruits are pedicellate berries with a cup-shaped hypanthium and contain ca. 15 lensoidal reniform seeds, each with a curved embryo and ornamented with concentric ridges. The combined characters refute the prior placement in Araliaceae, and rule out affinities with most extant clades of angiosperms. Conclusions The distinctive combination of observed features does not coincide with any extant family. Among extant orders of Eudicots, the fossil seems to conform most closely to the order Caryophyllales, but key differences remain. This example indicates that the vegetation of ca. 47 million years ago included some taxa that cannot readily be placed in modern families and genera

Palynotaxonomy of Neotropical species of Paullinia L. (Sapindaceae)

Paullinia is the second-largest genus within the Sapindaceae, with approximately 200 species. It predominantly comprises lianas that inhabit humid forests, mainly the Amazon and Atlantic forests in Brazil. This study aimed to characterize the pollen morphology of 60 species of Paullinia, examining the potential of pollen characters as morphological markers to support the systematics of the genus. The pollen material was obtained from exsiccatae of flower buds from major herbaria. Pollen grains were acetolyzed, measured, described, and illustrated using light microscopy. Scanning electron microscopy was used for accurate descriptions of surface features. The analyzed characters included pollen shape, size, aperture type and number, and exine ornamentation. The similarity of pollen characters between species was analyzed using hierarchical cluster analysis and principal component analysis. The results showed that pollen grains of Paullinia species are shed in monads, heteropolar in most species and isopolar in some others, medium or large in size, oblate or suboblate, and 3- or 3-4-porate, with perforate sexine ornamentation in most species and microreticulate in some others. Multivariate analyses revealed that pollen morphology is informative and holds taxonomic potential, enabling grouping based on the similarity of the unique pollen characters of the genus. Species dispersion on the PCA biplot showed that the five clusters formed by HCA were robust, suggesting that quantitative and qualitative pollen characters exhibit consistency with regard to the similarity species. The palynological findings presented here contribute to enhancing our understanding of the morphological characters, aiding in the taxonomy and systematics of the genus.

Analysis of Rfo-Mediated Network in Regulating Fertility Restoration in Brassica oleracea

Ogura cytoplasmic male sterility (CMS) lines play a crucial role in the utilization of heterosis. However, valuable traits, such as disease resistance genes from Ogura CMS hybrids, are challenging to incorporate for germplasm innovation, particularly in cabbage and broccoli. To date, the Rfo-mediated network regulating fertility restoration remains largely unexplored. In this study, we conducted a transcriptomic analysis of broccoli flower buds from Ogura CMS SFB45 and its Rfo-transgenic fertility restoration line, pRfo, at different stages of pollen development. Gene Ontology (GO) terms such as “pollen exine formation”, “flavonoid metabolic and biosynthetic processes”, and “pollen wall assembly”, along with Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways including “flavonoid biosynthesis”, “MAPK signaling pathway-plant”, and “ABC transporters”, were significantly enriched. We identified five differentially expressed genes (DEGs) involved in tapetum-mediated callose metabolism, thirty-four DEGs related to tapetum-mediated pollen wall formation, three DEGs regulating tapetum programmed cell death (PCD), five MPKs encoding DEGs, and twelve DEGs associated with oxidative phosphorylation. Additionally, yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays demonstrated that RFO directly interacts with ORF138 at the protein level. These findings provide valuable insights into the fertility recovery mechanisms regulated by Rfo in broccoli and offer important clues for breeders aiming to enhance Ogura CMS hybrids in Brassica oleracea.

Performance Analysis and Operation Parameter Optimization of Shaker-Type Harvesting for Camellia Fruits

This study aims to address the challenges of achieving a high harvesting rate and low flower bud damage rate during the harvesting of camellia fruits. To this end, a dynamic model of the camellia osmantha tree and a self-developed shaker-type harvesting machine were used as research subjects. The first 24 natural frequencies and mode shapes of the camellia tree were solved using the finite element method, and the effects of vibration frequency, excitation position, and vibration duration on the harvesting rate and flower bud damage rate were quantitatively analyzed through an orthogonal experiment. The numerical analysis results indicate that the camellia tree exhibits good response characteristics at vibration frequencies of 10–15.5 Hz and 38.5 Hz. The three-factors orthogonal experiment figured out that the optimal operational parameters for shaker-type harvesting were determined to be a vibration duration of 30 s, a motor output frequency of 12.5 Hz, and a gripping position height of 50 to 60 cm above the ground. Meanwhile, under these operational parameters, the harvesting efficiency reached 96.97%, while the flower bud damage rate was only 6%.

Unveiling the Spectacular Performance of Diverse Chrysanthemum Varieties in Flowering, Quality and Yield

A comprehensive research initiative conducted in Jhalawar 2019-20 focused on evaluating the genetic diversity and performance of various chrysanthemum varieties. The aim of this study was to evaluate the genetic variability and assess the varietal performance of chrysanthemum (Dendranthema grandiflora Tzvelev) under the specific agro-climatic conditions of Jhalawar. The study sought to identify high-performing varieties and quantify key genetic traits relevant to yield and quality characteristics, with the goal of supporting selection efforts for enhanced chrysanthemum production in the region. This investigation was conducted at the Floriculture and Landscaping block of the College of Horticulture and Forestry, Jhalawar, Rajasthan. The experimental work was carried out during the winter season of the year 2019-20, capitalizing on the local climate to evaluate varietal responses under Jhalawar conditions. The experiment employed a Randomized Block Design (RBD) with multiple replications to ensure robust data. Different chrysanthemum varieties were planted in designated plots, and observations on traits such as flower yield, flower quality, and growth parameters were recorded periodically. Statistical analysis, including ANOVA, was performed to detect significant differences among the varieties. This analysis helped in identifying high-performing varieties suited for Jhalawar conditions and provided insights into genetic variability for potential selection and breeding programs. Ten different genotypes were carefully chosen for the study, including Marigold, Poornima Pink, Dall White, Calcutta Shantini, Karnool, Poornima Red, Dall Yellow, Poornima White, Poornima Yellow and Dundi for in-depth analysis.A randomised block design with three replications was used in the experiment. Cultivar 'Calcutta Shantini' exhibited the maximum days taken to first flower bud emergence of plant (51.50 days) and the maximum number of flowers per plant (269.90). Conversely, cv. 'Dall Yellow' showed the shortest duration to fifty percent flowering (67.64 days). Notably, cv. 'Dundi' displayed the maximum flower diameter (7.47 cm), while cv. 'Poornima Pink' had the longest flower stalk (13.09 cm). Remarkably, cv. 'Marigold' demonstrated the highest flower fresh weight (63.67 gm), dry weight (14.41 gm), and shelf life (4.67 day).

Vitrification-cryopreservation of Shoot Tips Excised from Dormant Bulbs in Fritillaria przewalskii Maxim: Assessing Histological lnjuries and Evaluating Genetic Fidelity in Cryo-Derived Plants

Fritillaria przewalskii Maxim. an essential medicinal plant in the Fritillaria genus of the Liliaceae family, is widely used in traditional medicine. This study focused on developing a cryopreservation protocol for F. przewalskii, an endangered and endemic species in China. We aimed to determine if ex vitro bulbs from field-grown F. przewalskii plants could serve a source of shoot tips for cryopreservation. Key factors influencing cryopreservation outcomes were studied using a vitrification-based approach. Prior to cryopreservation, cold hardening and sucrose preculture conditions were optimized. The best results were achieved by hardening bulbs at 4℃ for 3-4 months,followed by surface disinfection and isolation of 2-5mm Shoot tips. The tips were then then precultured on a medium with 0.5M sucrose for 3 days. Cryopreservation steps included a 20-minute loading treatment, 60-minute PVS2 dehydration at room temperature, and storage in liquid nitrogen more than one hour. After thawing, this protocol resulted in 93% shoot survival rate, with tips regenerating into small bulbs within 5 weeks without intermediary callus formation. Histological analysis showed that while cooling and rewarming caused severe bud damage, apical meristem cells are the primary survival sites. Although loading and PVS2 treatment induced cell plasmolysis, it was not lethal. Optimal PVS2 treatment enhanced cellular dehydration resistance, promoting cell viability at ultralow temperature. RAPD analysis of regenepercentaged plants showed no genetic variation, confirming strong genetic stability. The direct use of ex vitro shoot tips provides a straightforward and effective cryopreservation method for F. przewalskii, combining convenience, efficiency, and genetic stability.

Systematic profiling and analysis of growth and development responsive DE-lncRNAs in cluster bean (Cyamopsis tetragonoloba)

Long non-coding RNAs (lncRNAs) play crucial role in regulating genes involved in various processes including growth & development, flowering, and stress response in plants. The study aims to identify and characterize tissue-specific, growth & development and floral responsive differentially expressed lncRNAs (DE-lncRNAs) in cluster bean from a high-throughput RNA sequencing data. We have identified 3309 DE-lncRNAs, with an average length of 818 bp. Merely, around 4 % of DE-lncRNAs across the tissues were found to be conserved as rate of evolution of lncRNAs is high. Among the identified DE-lncRNAs, 204 were common in leaf vs. shoot, leaf vs. flower and flower vs. shoot. A total of 60 DE-lncRNAs targeted 10 protein-coding genes involved in flower development and initiation processes. We investigated 179 tissue-specific DE-lncRNAs based on tissue specificity index. Three DE-lncRNAs: Cb_lnc_0820, Cb_lnc_0430, Cb_lnc_0260 and their targeted genes shown their involvement in floral development and stress mechanisms, which were validated by Quantitative real-time PCR (qRT-PCR). The identified DE-lncRNAs were expressed higher in flower bud than in leaf and similar expression pattern was observed in both RNA-seq data and qRT-PCR analyses. Notably, 362 DE-lncRNAs were predicted as eTM-lncRNAs with the participation of 84 miRNAs. Whereas 46 DE-lncRNAs were predicted to possess the internal ribosomal entry sites (IRES) and can encode for small peptides. The regulatory networks established between DE-lncRNAs, mRNAs and miRNAs have provided an insight into their association with plant growth & development, flowering, and stress mechanisms. Comprehensively, the characterization of DE-lncRNAs in various tissues of cluster bean shed a light on interactions among lncRNAs, miRNAs and mRNAs and help understand their involvement in growth & development and floral initiation processes. The information retrieved from the analyses was shared in the public domain in the form of a database: Cb-DElncRNAdb, and made available at http://backlin.cabgrid.res.in/Cb-DElncRNA/index.php, which may be useful for the scientific community engaged in future breeding programs of cluster bean.

MdILL6 regulates xylem and vessel development to control internode elongation in spur‐type apple

AbstractSpur‐type varieties play an important role in facilitating high‐density plantings. However, the underlying mechanisms of internode elongation in spur‐type varieties are poorly understood. In this research, we investigated the morphological phenotype of annual shoots in four spur‐type varieties (‘Miyazak’, ‘Jinfu 18’, ‘Yanfu No. 6’, and ‘Liquan spur’) and four standard‐type varieties (‘Aomorifu’, ‘Shou Fuji’, ‘Yanfu No. 10’, and ‘Yanfu No. 3’). Compared with standard‐type varieties, spur‐type varieties had a shorter shoot length, an average internode length and a smaller xylem size. The content of Jasmonic acid (JA) and Jasmonic acid isoleucine (JA‐Ile) significantly increased in spur‐type varieties, accompanied by an increase in the expression of JA biosynthesis and signal transduction genes. Exogenous methyl jasmonate (MeJA) inhibited plant height, xylem size, and vessel area. Additionally, we identified an IAA‐Leucine Resistant1‐like Hydrolase family member, MdILL6, which was highly expressed in spur‐type varieties and mature stems. MdILL6 was mainly expressed in the shoot tips and stem, and its protein was located on the endoplasmic reticulum. Overexpression of MdILL6 in apple inhibited plant height and average internode length by decreasing xylem size and vessel area. Our results revealed a molecular mechanism of spur‐type variety development affected by the JA pathway and suggest strategies for genetic improvement and regulation of spur‐type varieties.

Cryopreservation of Fegra Fig (Ficus palmata Forssk.) and Genetic Fidelity of the Recovered Micropropagated Plants

Cryopreservation allows for the long-term storage of biological materials, ensuring their viability for future use and preserving biodiversity. This study aimed to develop an efficient protocol for the long-term in vitro conservation of fegra fig. In vitro precultured shoot tips of fegra fig with 0.3 M sucrose showed the highest regrowth percentage (100%) before plunging into liquid nitrogen. After plunging into liquid nitrogen, the regrowth percentage was 43.33%. Following cryopreservation, the recovered shoots were rooted and acclimatized to ex vitro conditions. The genetic fidelity of the acclimatized 8-week-old fegra fig plantlets after cryopreservation with their mother plant was tested using randomly amplified polymorphic DNA (RAPD), inter simple sequence repeats (ISSR), and start codon targeted (SCoT) molecular markers. Genetic similarity between the stored plantlets with their mother plant was 100% ensuring uniformity and true-to-type regenerated plants following cryopreservation. This study presents, for the first time, an efficient protocol for the genetic conservation of fegra fig.

Spring growth of lucerne (Medicago sativa L.) after different times of winter defoliation

The aim of this work was to determine if autumn/winter defoliation affected the time of lucerne stem extension in spring. Two experiments were established at the Field Research Centre, Lincoln University. Experiment 1 was established on 01/06/2022 using an existing two year old stand of “Force 4” lucerne. There were four canopy defoliation dates (1/06, 03/07, 17/07, 1/08). Experiment 2 repeated the treatments on the same paddock in the following year on eight defoliation dates (1/5, 15/5, 1/6, 15/6, 3/7, 17/7, 1/8 and 15/8). In both experiments, five stems were marked in each plot and stem height was measured weekly. The start of stem extension was unaffected by canopy defoliation date in either 2022 (P = 0.20) or 2023 (P = 0.17). Initiation of stem extension was triggered by a base photoperiod of 11.1 ± 0.2 h. This meant the thermal time accumulated from final defoliation to the start of stem extension differed among treatments. These results suggest the time of autumn/winter defoliation (the winter clean-up graze) will not affect the time of the first spring grazing, provided the developing basal buds are not removed. All stands reached 150 mm height by mid-September and produced 3.0 t/ha of dry matter by the end of the month. This suggests, grazing of the first paddock at Lincoln should commence in the first week of September to create a staggered start to rotational grazing that can maximise lucerne yield and quality for animal liveweight production.

Gusto por la fruta: primer registro de Rekoa marius (Lucas, 1857) (Lepidoptera: Lycaenidae: Eumaeini) sobre Averrhoa carambola L. (Oxalidales: Oxalidaceae)

Information on the natural history of Rekoa marius (Lucas, 1857) is presented through the first record of the species on Averrhoa carambola L. The larvae of this lepidopteran were collected on A. carambola and reared under laboratory conditions. Eggs were found on the flower bud, inflorescence and peduncle near the flower. All larval stages feed on flower buds, while the last larval stage also feeds on green and ripe fruits. Pupae with egress holes of different diameters were found, probably of parasitoids. Since Oxalidaceae species are rich in oxalic acid, R. marius may be a potential model for future studies on the mechanisms involved in the response of this species to oxalic acid present in its host plant.

Integrated Analysis of microRNAs and Transcription Factor Targets in Floral Transition of Pleioblastus pygmaeus

Bamboo plants have erratic flowering habits with a long vegetative growth and an uncertain flowering cycle. The process of floral transition has always been one of the hot and intriguing topics in bamboo developmental biology. As master modulators of gene expression at the post-transcriptional level, miRNAs play a crucial role in regulating reproductive growth, especially in floral transition of flowering plants. Pleioblastus pygmaeus is a kind of excellent ground cover ornamental bamboo species. In this study, we performed miRNA expression profiling of the shoot buds and flower buds from the bamboo species, to investigate flowering-related miRNAs in bamboo plants. A total of 179 mature miRNAs were identified from P. pygmaeus, including 120 known miRNAs and 59 novel miRNAs, of which 96 (61 known miRNAs and 35 novel miRNAs) were differentially expressed in the shoots at different growth stages. Based on target gene (TG) prediction, a total of 2099 transcription factors (TFs) were annotated to be TGs of the 96 differentially expressed miRNAs (DEMs), corresponding to 839 recordings of DEM-TF pairs. In addition, we identified 23 known DEMs involved in flowering and six known miRNAs related to floral organ development based on previous reports. Among these, there were 11 significantly differentially expressed miRNAs, with 124 TF targets corresponding to 132 DEM-TF pairs in P. pygmaeus. In particular, we focused on the identification of miR156a-SPL (SQUAMOSA Promoter-Binding protein-Like) modules in the age pathway, which are well-known to regulate the vegetative-to-reproductive phase transition in flowering plants. A total of 36 TF targets of miR156a were identified, among which there were 11 SPLs. The Dual-Luciferase transient expression assay indicated miR156a mediated the repression of the PpSPL targets in P. pygmaeus. The integrated analysis of miRNAs and TGs at genome scale in this study provides insight into the essential roles of individual miRNAs in modulating flowering transition through regulating TF targets in bamboo plants.

Gas exchange in yellow passion fruit hybrids in the Semiarid region

Agronomic characterization and exploitation of the genetic variability in plants of the Passiflora can reveal important genetic resources because the Passiflora species grown under semiarid conditions make important contributions to breeding. The aim of this work was to evaluate the vegetative and physiological characteristics of fifteen yellow passion fruit hybrids in semiarid conditions. The experiment was conducted at IF Baiano – campus Guanambi, Bahia, Brazil. The 15 treatments were 10 genotypes: H09-10; GP09-02; H09-02; H09-14; H09-07; H09-09; FOP09; GP09-03; H09-30; FOP08 from the Active Germplasm Bank of the Genetic Breeding Program of Embrapa Cassava and Fruits, and five commercial hybrids: FB200; FB300; BRS SC; BRGA; BRS Rubi. The treatments were arranged in a randomized block design, with three replications and five observational units per plot. Vegetative characteristics (main branch length, number of functional leaves, number of nodes, and number of flower buds) were measured at full vegetative development, 90 days after transplanting (DAT). Hybrid H09-10 is the earliest in flowering, physiologically more efficient in the morning, closes stomata in the afternoon, regulates transpiration, and has lower leaf temperature, higher photosynthesis rate, and more efficient water use. Gas exchanges and photosynthesis rates, at 300 DAT, vary between hybrids and reading times: photosynthesis is higher in the morning while transpiration is greater in the afternoon. The reduction in carboxylation efficiency is related to non-stomatal factors. Gas exchange variables of the genotypes tend to be directly correlated with the photosynthetically active radiation incident on the leaf

Production of Microspore-Derived Plants by Anther Culture of Cyclamen coum

Cyclamen is one of the most important ornamental crops sold worldwide as a potted flower for winter production. Cyclamen species take up a wide swathe of habitats across Turkey. Ten wild Cyclamen species grow naturally in Turkey, some of them endemic. This study aimed to produce haploid plants of C. coum using anther culture. The microspore developmental stage was evaluated by staining anther with acetocarmine (%2), and then the stage was correlated with bud size. It was determined that the buds between 7.64-8.23 mm had the appropriate bud size for the late uninuclear stage. Anthers were cultured in B5 medium containing different levels of NAA (0.1, 1, 2 mg/L), 2,4-D (0.1, 1, 2 mg/L), and kinetin (0, 1 mg/L), 90 g/L sucrose and 3 g/L gelrite for haploid embryo production. Anthers were kept at 4°C for 4 days after culture. The explants were incubated at 24°C in a completely dark condition until the embryo was formed, then embryos were transferred to hormone-free media in 8:16 hours (light: dark) photoperiod. The experiment was carried out for two years. In the first year, 12 different media were examined in view of regeneration and the experiments were continued with selected 7 media in the second year. The highest callus regeneration rates were %5.71 and 14.5% and the highest embryo induction rates varied between 8.57% and 4.0% in the first and second year respectively. Embryo/callus formation was observed in 7 of a total of 12 different media tested for haploid plant production, and the best media were kinetin (1 mg/L) + NAA (1, 2 mg/L) and kinetin (1 mg/L) +2,4-D (2 mg/L). Our findings indicated that cold pre-treated anther explants collected at appropriate flower bud size resulted in embryo production Additionally, B5 medium supplemented with NAA and kinetin ensured successful embryo regeneration from anther explants in wild C. coum.

Plant hormone signaling is involved in regulating flower bud size of daylily

To explore the role and metabolic differences of plant hormones in regulating the flower bud size of daylily, we collected the flower buds from two daylily varieties 'Datong Huanghua' and 'Dongbei Huanghua' at the young bud, green, yellowing, and yellow stages for transcriptome sequencing. The differentially expressed genes (DEGs) were screened, and the exogenous plant hormone spraying experiments were conducted. A total of 199 DEGs related to the biosynthesis and metabolism of plant hormones was screened out at different flower development stages of 'Datong Huanghua' and 'Dongbei Huanghua'. These genes regulated the biosynthesis and metabolism of six plant hormones: abscisic acid, gibberellin, auxin, jasmonate, cytokinin, and ethylene. The DEGs associated with auxin were the most, which suggested that auxin played a role in regulating flower bud development. The auxin response factor (ARF) presented up-regulated expression at all the four stages of flower bud development, indicating that ARF played a positive regulatory role throughout the flower bud development of daylily. The experiments with exogenous spraying of six hormones further verified that indole-3-acetic acid (IAA) significantly promoted the growth and increased the nutrient content in the flower buds of 'Datong Huanghua', suggesting that IAA played a role in regulating flower bud development. Our results laid a theoretical foundation for probing into the regulatory mechanism of flower bud development of 'Datong Huanghua' and 'Dongbei Huanghua'.

Transcription Factors Are Involved in Wizened Bud Occurrence During the Growing Season in the Pyrus pyrifolia Cultivar ‘Sucui 1’

Background: Flowers are important plant organs, and their development is correlated with yield in woody fruit trees. For Pyrus pyrifolia cultivar ‘Sucui 1’, the research on how DNA methylation accurately regulates the expression of TFs and affects the specific regulatory mechanism of flower bud wizening will help reduce wizened buds. Methods: Here, the DNA methylomes and transcriptomes of two types of flower buds from the Pyrus pyrifolia cultivar ‘Sucui 1’ were compared. Results: 320 differentially expressed transcription factors (TFs), in 43 families, were obtained from the wizened bud transcriptome versus the normal bud transcriptome. Most were members of the AP2/ERF, bHLH, C2H2, CO-like, MADS, MYB, and WRKY families, which are involved in flower development. As a whole, the methylation level of TFs in the ‘Sucui 1’ genome increased once flower bud wizening occurred. A cytosine methylation analysis revealed that the methylation levels of the same gene regions in TFs from two kinds of buds were similar. However, differentially methylated regions were found in gene promoter sequences. The combined whole-genome bisulfite sequencing and RNA-Seq analyses revealed 162 TF genes (including 164 differentially methylated regions) with both differential expression and methylation differences between the two flower bud types. Among them, 126 were classified as mCHH-type methylation genes. Furthermore, the transcriptional down regulation of PpbHLH40, PpERF4, PpERF061, PpLHW, PpMADS6, PpZF-HD11, and PpZFP90 was accompanied by increased DNA methylation. However, PpbHLH130, PpERF011, and PpMYB308 displayed the opposite trend. The expression changes for these TFs were negatively correlated with their methylation states. Conclusions: Overall, our results offer initial experimental evidence of a correlation between DNA methylation and TF transcription in P. pyrifolia in response to bud wizening. This enriched our understanding of epigenetic modulations in woody trees during flower development.

Efficacy of Plant Tissue Culture Techniques for Eliminating Black Mulberry Idaeovirus (BMIV) from Infected Black Mulberry (Morus nigra)

Obtaining virus-free plants is a crucial step in disease management that enables reliable and profitable fruit farming. The present study applied various in vitro virus elimination protocols, including apical shoot culture, chemotherapy, thermotherapy, cryotherapy, and their combination, to eliminate black mulberry Idaeovirus (BMIV) from sour black mulberry. First, a shoot tip (0.5–2 mm) culture protocol was optimized, and four ribavirin concentrations (0, 10, 20, and 30 mg/L) were investigated over five weeks as a form of chemotherapy (ch). For the first thermotherapy treatment (Ch + Th1st), chemotherapy treatment was followed by a gradual increase in the temperature (24–33 °C). In another experiment (Th2nd + Ch), in vitro shoots were incubated in the dark for two weeks at two different temperatures (35 ± 1 °C and 37 ± 1 °C, for one week each). Subsequently, the shoot tips were incubated with various ribavirin doses. Finally, cryotherapy (Cr) was used with or without immersing the shoot tips in liquid nitrogen. A two-step RT-PCR was performed to assess the presence of the virus in 7–8-week-old in vitro plants. Th2nd + Ch significantly increased the shoot tip burst and plant survival/morphogenesis compared to the other treatments. Except for the application of cryotherapy, the protocols eliminated BMIV in different proportions, and the highest virus elimination rate (50%) was obtained by applying 30 mg/L ribavirin during the Ch + Th1st treatment. These findings are essential in preventing the dissemination of the virus and enabling the safe movement of germplasm around the world.