Flower Differentiation Research Articles

Jean-Baptiste Payer (1818–1860), prolific botanist and enlightened French citizen: his legacy in flower development and a need for a new, global compendium

ABSTRACT Jean-Baptiste Payer was among the pioneer botanists who promoted ontogeny as a clue to understanding the morphological nature and affinities of floral parts. He can be rightly seen as the father of floral developmental studies. In his magnus opus, Traité d’organogénie comparée de la fleur, he compared developmental stages across 333 species from 130 families sensu APGIV to explain phenomena such as the integration of the receptacle in the flower, the nature of the perianth, congenital fusion, shifts in stamen number, and the homology of carpels. His work is breathtaking not only in its scale and beauty, but also in providing a solid scientific basis for understanding the processes involved in the differentiation of flowers. Despite being pre-Darwinian, his research demonstrates the potential for evolutionary changes in flowers, in the context of the understanding of angiosperm classification at that time. Many of Payer’s ideas are still up-to-date and his observations are of great value in contemporary studies. In addition to botany, Payer had a lightning career in politics starting from the 1848 revolution. First a rioter, he then served two terms in the Constituent Assembly, before going back to science in 1852. In poor health, he died at the age of 42. This article aims at celebrating Payer as a scientist and a politician. We highlight a need for a new, global (encompassing at least all angiosperm orders) compendium on flower development that will facilitate analyses of evolutionary transitions of ontogenetic pathways. An outline of this research program is provided.

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.

Gene Regulatory Network Controlling Flower Development in Spinach (Spinacia oleracea L.).

Spinach (Spinacia oleracea L.) is a dioecious, diploid, wind-pollinated crop cultivated worldwide. Sex determination plays an important role in spinach breeding. Hence, this study aimed to understand the differences in sexual differentiation and floral organ development of dioecious flowers, as well as the differences in the regulatory mechanisms of floral organ development of dioecious and monoecious flowers. We compared transcriptional-level differences between different genders and identified differentially expressed genes (DEGs) related to spinach floral development, as well as sex-biased genes to investigate the flower development mechanisms in spinach. In this study, 9189 DEGs were identified among the different genders. DEG analysis showed the participation of four main transcription factor families, MIKC_MADS, MYB, NAC, and bHLH, in spinach flower development. In our key findings, abscisic acid (ABA) and gibberellic acid (GA) signal transduction pathways play major roles in male flower development, while auxin regulates both male and female flower development. By constructing a gene regulatory network (GRN) for floral organ development, core transcription factors (TFs) controlling organ initiation and growth were discovered. This analysis of the development of female, male, and monoecious flowers in spinach provides new insights into the molecular mechanisms of floral organ development and sexual differentiation in dioecious and monoecious plants in spinach.

Dynamic transcriptome analysis provides molecular insights into underground floral differentiation in Adonis Amurensis Regel & Radde

Understanding flower developmental processes is a prerequisite for improving flowering ‘plants’ production. Adonis amurensis is a fascinating spring ephemeral plant that develops its flower organs underground. Nevertheless, knowledge of the molecular mechanisms driving this particular process is scarce. Herein, we examined transcriptional changes during underground flower differentiation in A. amurensis and unveiled key differently regulated genes and pathways. High-throughput RNA sequencing of meristems at different flower developmental stages, including flower primordium (FP), sepal stage (SE), perianth primordium (PE), stamen stage (ST), and pistil stage (PI), identified 303,234 unigenes that showed 44.79% similarity with sequences in Aquilegia coerulea. Correlations, principal component, and differentially expressed genes (DEGs) analyses revealed that few molecular changes occurred during the transition from PE to ST. Many DEGs exhibited stage-specific regulations. Transcription factor (TF) and phytohormone family genes are critical regulators of the floral differentiation process in A. amurensis. The most differentially regulated TFs were MADS, FAR1, MYBs, AP2/ERF, B3, C2H2, and LOBs. We filtered out 186 candidate genes for future functional studies, including 18 flowering/circadian-related, 32 phytohormone-related, and TF family genes. Our findings deepen our understanding of the underground flower differentiation process and offer critical resources to dissect its regulatory network in A. amurensis. These findings establish a foundational platform for researchers dedicated to exploring the unique phenotypic characteristics of this specific flowering modality and delving into the intricate molecular mechanisms underpinning its regulation and expression.

G1 Interacts with OsMADS1 to Regulate the Development of the Sterile Lemma in Rice.

Flower development, as the basis for plant seed development, is principally conserved in angiosperms. At present, a number of genes regulating flower organ differentiation have been identified, and an ABCDE model has also been proposed. In contrast, the mechanism that regulates the development of the sterile lemma remains unclear. In this study, we identified and characterized a rice floral organ mutant, M15, in which the sterile lemma transformed into a lemma-like organ. Positional cloning combined with a complementary experiment demonstrated that the mutant phenotype was restored by LONG STERILE LEMMA1/(G1). G1 was expressed constitutively in various tissues, with the highest expression levels detected in the sterile lemma and young panicle. G1 is a nucleus-localized protein and functions as a homomer. Biochemical assays showed that G1 physically interacted with OsMADS1 both in vitro and in vivo. Interestingly, the expression of G1 in M15 decreased, while the expression level of OsMADS1 increased compared with the wild type. We demonstrate that G1 plays a key role in sterile lemma development through cooperating with OsMADS1. The above results have implications for further research on the molecular mechanisms underlying flower development and may have potential applications in crop improvement strategies.

Transcriptomic analysis reveals the molecular basis of photoperiod-regulated sex differentiation in tropical pumpkins (Cucurbita moschata Duch.)

BackgroundPhotoperiod, or the length of the day, has a significant impact on the flowering and sex differentiation of photoperiod-sensitive crops. The “miben” pumpkin (the main type of Cucurbita moschata Duch.) is well-known for its high yield and strong disease resistance. However, its cultivation has been limited due to its sensitivity to photoperiod. This sensitivity imposes challenges on its widespread cultivation and may result in suboptimal yields in regions with specific daylength conditions. As a consequence, efforts are being made to explore potential strategies or breeding techniques to enhance its adaptability to a broader range of photoperiods, thus unlocking its full cultivation potential and further promoting its valuable traits in agriculture.ResultsThis study aimed to identify photoperiod-insensitive germplasm exhibiting no difference in sex differentiation under different day-length conditions. The investigation involved a phenotypic analysis of photoperiod-sensitive (PPS) and photoperiod-insensitive (PPIS) pumpkin materials exposed to different day lengths, including long days (LDs) and short days (SDs). The results revealed that female flower differentiation was significantly inhibited in PPS_LD, while no differences were observed in the other three groups (PPS_SD, PPIS_LD, and PPIS_SD). Transcriptome analysis was carried out for these four groups to explore the main-effect genes of sex differentiation responsive to photoperiod. The main-effect gene subclusters were identified based on the principal component and hierarchical cluster analyses. Further, functional annotations and enrichment analysis revealed significant upregulation of photoreceptors (CmCRY1, F-box/kelch-repeat protein), circadian rhythm-related genes (CmGI, CmPRR9, etc.), and CONSTANS (CO) in PPS_LD. Conversely, a significant downregulation was observed in most Nuclear Factor Y (NF-Y) transcription factors. Regarding the gibberellic acid (GA) signal transduction pathway, positive regulators of GA signaling (CmSCL3, CmSCL13, and so forth) displayed higher expression levels, while the negative regulators of GA signaling, CmGAI, exhibited lower expression levels in PPS_LD. Notably, this effect was not observed in the synthetic pathway genes. Furthermore, genes associated with ethylene synthesis and signal transduction (CmACO3, CmACO1, CmERF118, CmERF118-like1,2, CmWIN1-like, and CmRAP2-7-like) showed significant downregulation.ConclusionsThis study offered a crucial theoretical and genetic basis for understanding how photoperiod influences the mechanism of female flower differentiation in pumpkins.

Effect of Short Day and Low Temperature at the Nursery Stage on the Inflorescence and Yield of Six Different Strawberry (Fragaria ananassa Dutch.) Cultivars in a Soilless Culture System

In Korea, the majority of strawberry cultivation follows a forcing culture, where planting occurs in mid-September after the flower differentiation, and harvesting begins at the end of November. October and November constitute off-season, resulting in higher prices. The accelerated forcing culture involves artificially promoting flower differentiation to expedite strawberry harvest. This study aimed to identify the most suitable schedule for strawberry cultivation using the short-day and low-temperature treatments through greenhouse environmental control during the nursery stage. The selection of the most suitable cultivars for accelerated forcing culture among Korean breeding cultivars (‘Sulhyang’, ‘Kuemsil’, ‘Kingsberry’, ‘Vitaberry’, ‘Jukhyang’, and ‘Altaking’) was also part of the objectives. The nursery treatments were initiated on 4 July, 14 July, and 25 July. After approximately 5 weeks of treatment, transplanting was carried out. The control group was transplanted on 15 September. When night-chilling nursery treatment was applied on 4 July, followed by transplanting on 11 August, all six cultivars exhibited flowering earlier compared to the control group, leading to increased early yield. Particularly, the ‘Sulhyang’ cultivar showed the highest marketable yield at 68.6 g per plant in October. This research contributes to identifying the nursery cultivation schedule for off-season strawberry production and selecting suitable cultivars, and is expected to contribute to increased farm income.

Mutagenic effect of ultraviolet rays on sex expression in summer squash genotypes

The present study aimed to induce genetic variations within the control of sex expression in summer squash using ultraviolet rays (UV) as a physical source of mutations in plants. Because the sex expression in summer squash is fundamentally controlled mainly by genetics and partially by the environment. Therefore, this study tries to increase floral differentiation of female flowers, as well as decrease male flowers developed per plant, because summer squash usually exhibit more male flowers and lower female flowers. This will cause decreases in fruits yield per plant. This study was designed in a randomized complete block design with a factorial investigation. It was included four genotypes of summer squash subjected to four exposure periods of UV rays, with three repetitions for each experimental unit. The results showed that genotype number four increased the features of female flowers by 28% and 14% at 4 and 8 minutes of exposure period, respectively. The 12 – minute exposure period significantly increased floral differentiation among all genotypes toward male flowers developed per plant. Meanwhile, genotype number two enhanced floral differentiation toward female flowers by 14% at 8 minutes of exposure period, indicating that these few periods of exposure to UV irradiation may be responsible for induced benefit mutations in cucurbits affected on sex expression, as it induced high number of female flowers. The results indicated that UV irradiation had a direct role in promoting floral differentiation as it inducement higher female flowers in some genotypes leading to improve floral characteristics, as a consequence increased fruits yield per plant.

Sex-Related Gene Network Revealed by Transcriptome Differentiation of Bisexual and Unisexual Flowers of Orchid Cymbidium tortisepalum

Despite extensive research on orchid reproductive strategies, the genetic studies of sex differentiation in the orchid family are still lacking. In this study, we compared three sexual phenotypes of Cymbidium tortisepalum bisexual flowers as well as female and male unisexual mutants. Through comparative transcriptomes, we analyzed the sex-biased differentially expressed genes (DEGs) and gene co-expression networks of sex organs (gynostemium and ovary) among them, identified the candidate genes of sex differentiation, and validated their expression by qRT-PCR. The C. tortisepalum unisexual mutants with degenerated phenotypes were compared to the bisexual plants with respect to both the flower organs and plant morphologies. Totally, 12,145, 10,789, and 14,447 genes were uniquely expressed in the female, male, and hermaphrodite sex organs, respectively. A total of 4291 sex-biased DEGs were detected among them, with 871, 2867, and 1937 DEGs in the comparisons of bisexual vs. female, bisexual vs. male, and male vs. female flowers, respectively. Two co-expressed network modules, with 81 and 419 genes were tightly correlated with female sexual traits, while two others with 265 and 135 genes were highly correlated with male sexual traits. Two female-biased hub genes (CtSDR3b and CtSDR3b-like) nested in the female modules, the homologs of maize sex determinant tasselseed2, may control the feminization of C. tortisepalum. At the same time, two male-biased hub genes (CtYAB2 and CtYAB5) nested in the male modules, the homologs of grape sex determinant VviYABBY3, may control the androphany of C. tortisepalum. This study discovered the molecular regulation networks and proposed a model for orchid sex differentiation, therefore providing for the first time the genetic basis for the sex separation in the orchid family.

Comparative transcriptome analysis of dioecious floral development in Trachycarpus fortunei using Illumina and PacBio SMRT sequencing

BackgroundTrachycarpus fortunei is a plant with significant economic and ornamental value. Both male and female flowers of T. fortunei originate as bisexual flowers, and selective abortion occurs during floral development. However, the regulatory mechanisms underlying this process remain unclear in T. fortunei. In this study, transcriptome sequencing with Illumina and Pacific BioSciences (PacBio) single-molecule real-time (SMRT) platforms were used to investigate gene expression differences between male and female T. fortunei plants.ResultsA total of 833,137 full-length non-chimeric (FLNC) reads were obtained, and 726,846 high-quality full-length transcripts were identified. A total of 159 genes were differentially expressed between male and female flowers at all development stages. Some of the differentially expressed genes (DEGs) showed male bias, including serine/threonine-protein kinase (STPK), THUMP1 homolog and other genes. Through single-nucleotide polymorphisms(SNPs) identification, 28 genes were considered as potential sex-associated SNPs. Time-Ordered Gene Co-expression Network (TO-GCN) analysis revealed that MADS2 and MADS26 may play important roles in the development of female and male flowers T. fortune plants, respectively.ConclusionsThese findings provide a genetic basis for flower development and differentiation in T. fortunei, and improve our understanding of the mechanisms underlying sexual differentiation in T. fortunei.

Genome resequencing reveals the evolutionary history of garlic reproduction traits.

The propagation of cultivated garlic relies on vegetative cloves, thus flowers become non-essential for reproduction in this species, driving the evolution of reproductive feature-derived traits. To obtain insights into the evolutionary alteration of reproductive traits in the clonally propagated garlic, the evolutionary histories of two main reproduction-related traits, bolting and flower differentiation, were explored by genome analyses using 134 accessions displaying wide diversity in these two traits. Resequencing identified 272.8 million variations in the garlic genome, 198.0 million of which represent novel variants. Population analysis identified five garlic groups that have evolved into two clades. Gene expression, single-cell transcriptome sequencing, and genome-wide trait association analyses have identified numerous candidates that correlate with reproductive transition and flower development, some of which display distinct selection signatures. Selective forces acting on the B-box zinc finger protein-encoding Asa2G00291.1, the global transcription factor group E protein-encoding Asa5G01527.1, and VERNALIZATION INSENSITIVE 3-like Asa3G03399.1 appear to be representative of the evolution of garlic bolting. Plenty of novel genomic variations and trait-related candidates represent valuable resources for biological studies of garlic. Numerous selective signatures from genes associated with the two chosen reproductive traits provide important insights into the evolutionary history of reproduction in this clonally propagated crop.

The Sink–Source Relationship Regulated Camellia oleifera Flower Bud Differentiation by Influencing Endogenous Hormones and Photosynthetic Characteristics

To explore the reasons for the differences in flower bud differentiation in Camellia oleifera under different sink–source relationships, different types of new shoots (T1 and T2) were selected to represent different sink–source relationships (new shoots with one fruit borne alongside at the bottom of the new shoots-T1; new shoots without one fruit borne alongside at the bottom of the new shoots-T2), and the flower bud differentiation rate, endogenous hormones and photosynthetic characteristics were determined. With the increase in the sink, the flower differentiation rate decreased significantly and the IAA and GA3 content in the leaves and ABA content in the buds increased significantly, while the GA3 and ZT content in the buds decreased significantly, which were significantly and positively correlated with the flower differentiation rate, with correlation coefficients of 0.777 and 0.817, respectively. Furthermore, an increase in the number of sinks contributed significantly to the increase in soluble sugar and starch content in leaves, while the soluble sugar and starch content in flower buds decreased significantly with the increase in sinks, with maximum differences of 3.45 mg·g−1 (soluble sugar in leaves), 4.09 mg·g−1 (soluble sugar in flower buds), 7.08 mg·g−1 (starch in leaves) and 4.87 mg·g−1 (starch in flower buds), and the high soluble sugar and starch content in flower buds at preflower bud differentiation with correlation coefficients of 0.854 and 0.837, respectively. The chlorophyll content and net photosynthetic rate increased with increasing sinks. In the presence of fruit at the base of the new shoot, more 13C assimilates were allocated to fruit and less to flower buds, resulting in a decrease in the rate of flower bud differentiation. The 13C assimilate allocated to the flower buds of T1 (6.71 mg·g−1) was significantly lower than the 13C assimilate allocated to the flower buds of T2 (10.26 mg·g−1) during late bud differentiation, and the difference between T1 and T2 was greatest during this period. Our work demonstrated that the sink–source relationship regulated Camellia oleifera flower bud differentiation by influencing endogenous hormones and photosynthetic characteristics. To achieve stable production of Camellia oleifera in successive years in the future, the ratio of the number of new shoots of the two types in relation to the different sink–source relationships should be reasonable.

Highly sex specific gene expression in Jojoba

BackgroundDioecious plants have male and female flowers on separate plants. Jojoba is a dioecious plant that is drought-tolerant and native to arid areas. The genome sequence of male and female plants was recently reported and revealed an X and Y chromosome system, with two large male-specific insertions in the Y chromosome.ResultsA total of 16,923 differentially expressed genes (DEG) were identified between the flowers of the male and female jojoba plants. This represented 40% of the annotated genes in the genome. Many genes, including those responsible for plant environmental responses and those encoding transcription factors (TFs), were specific to male or female reproductive organs. Genes involved in plant hormone metabolism were also found to be associated with flower and pollen development. A total of 8938 up-regulated and 7985 down-regulated genes were identified in comparison between male and female flowers, including many novel genes specific to the jojoba plant. The most differentially expressed genes were associated with reproductive organ development. The highest number of DEG were linked with the Y chromosome in male plants. The male specific parts of the Y chromosome encoded 12 very highly expressed genes including 9 novel genes and 3 known genes associated with TFs and a plant hormone which may play an important role in flower development.ConclusionMany genes, largely with unknown functions, may explain the sexual dimorphisms in jojoba plants and the differentiation of male and female flowers.

Cloning and Functional Analysis of the VfRR17 Gene from tung tree (Vernicia fordii).

Tung tree (Vernicia fordii) is one of the four major woody oilseed species in China. However, its fruit yield is severely hampered by the low number of female flowers and the imbalanced male-to-female flower ratio, which is a problem that restricts the development of the oilseed industry. Previous research has demonstrated that the exogenous application of cytokinins can significantly augment the number of female flowers, although the underlying regulatory mechanism remains elusive. To elucidate the involvement of VfRR17, a member of the A-type ARRs family, in the exogenous cytokinin regulation of flower sexual differentiation in tung tree, this study conducted a comprehensive bioinformatic analysis of the physicochemical properties, structural characteristics, and evolutionary relationships of the protein encoded by VfRR17. Additionally, gene function analysis was performed using subcellular localization, qRT-PCR, and genetic transformation techniques. The findings revealed that the VfRR17 gene's coding region spanned 471 bp, encoding an unstable protein of 156 amino acids with a relative molecular mass of 17.4 kDa. Phylogenetic analysis demonstrated a higher similarity between VfRR17 of the tung tree and the RR17 gene of Jatropha curcas, Ricinus communis, Hevea brasiliensis, and other species within the Euphorbiaceae family compared to other species, with the greatest similarity of 86% observed with the RR17 gene of Jatropha curcas. The qRT-PCR analysis indicated that VfRR17 exhibited high expression levels during the early stage of tung tree inflorescence buds following 6-BA treatment, peaking at 24 h and displaying a 3.47-fold increase compared to that at 0 h. In female and male flowers of the tung tree, the expression in female flowers during the 1 DBF period was significantly higher than in male flowers, exhibiting a difference of approximately 47.91-fold. Furthermore, notable differential expression was observed in the root, leaf, and petiole segments of the tung tree under low-temperature stress at the 12-h time point. In transgenic Arabidopsis, the VfRR17 lines and wild-type lines exhibited significantly different flowering times under an exogenous 6-BA treatment at a concentration of 2 mg/L, with the VfRR17 lines experiencing an 11-day delay compared to the wild-type lines. Additionally, the number of fruit pods in VfRR17 transgenic Arabidopsis lines was significantly reduced by 28 compared to the wild-type lines at a 6-BA concentration of 3 mg/L. These findings suggest that VfRR17 likely plays a critical role in regulating flower development in response to exogenous 6-BA, providing valuable insights into the mechanisms underlying exogenous 6-BA-mediated regulation of female flower development in the tung tree.

Influence of brassinosteroids on sex allocation in walnut (Juglans regia L.) flowers

The effect of foliar treatment with brassinosteroid (BR) on gender distribution in flowers of walnut (Juglans regia L. cv. Chandler) was investigated. Grafted walnut saplings (‘Chandler’) on the wild walnut (Juglans regia L.) rootstock were planted into 70-liter pots with a soil: peat: perlite medium and grown in pots between 2016–2020. BRs (24-epibrassinolide; EBR and 22(S), 23(S)-homobrassinolide; HBR) were applied at a concentration of 1 mg L–1 for four consecutive years at the time of flower differentiation. The experimental design was completely randomized with three replicates. The results show that BR applications could alter the sexual distribution of the walnut’s flower. BRs application significantly increased the number of total flowers and female flowers per tree. The number of female flowers was also increased by the season. The highest number of female flowers (20.9) was observed in the trees in 2020 and the application of 1 mg L–1 of HBR. It was determined that the annual growth of the plant and the increase in the number of females and total flowers were positively related. The effect of BRs indicated that the response was BR-type specific.

Advances in Research on the Regulation of Floral Development by CYC-like Genes.

CYCLOIDEA (CYC)-like genes belong to the TCP transcription factor family and play important roles associated with flower development. The CYC-like genes in the CYC1, CYC2, and CYC3 clades resulted from gene duplication events. The CYC2 clade includes the largest number of members that are crucial regulators of floral symmetry. To date, studies on CYC-like genes have mainly focused on plants with actinomorphic and zygomorphic flowers, including Fabaceae, Asteraceae, Scrophulariaceae, and Gesneriaceae species and the effects of CYC-like gene duplication events and diverse spatiotemporal expression patterns on flower development. The CYC-like genes generally affect petal morphological characteristics and stamen development, as well as stem and leaf growth, flower differentiation and development, and branching in most angiosperms. As the relevant research scope has expanded, studies have increasingly focused on the molecular mechanisms regulating CYC-like genes with different functions related to flower development and the phylogenetic relationships among these genes. We summarize the status of research on the CYC-like genes in angiosperms, such as the limited research conducted on CYC1 and CYC3 clade members, the necessity to functionally characterize the CYC-like genes in more plant groups, the need for investigation of the regulatory elements upstream of CYC-like genes, and exploration of the phylogenetic relationships and expression of CYC-like genes with new techniques and methods. This review provides theoretical guidance and ideas for future research on CYC-like genes.

Identification and Expression Profiles of the WRKY Gene Family in Pecan (<i>Carya illinoinensis</i>)

WRKY gene family encodes a large transcription factor family that play critical roles in various physiological processes. However, a systematic analysis of the WRKY transcription factor family has not been reported in pecan ( Carya illinoinensis ). In this study, a total of 89 putative pecan  WRKY  genes ( CiWRKYs ), named  CiWRKY1-89 , were identified from the whole genome of pecan. Most of WRKY domain sequences in CiWRKY proteins were “WRKYGQK”, but there were “WRKYGKK” in CiWRKY19, CiWRKY27 and CiWRKY88, and “WKKYGQK” in CiWRKY85. All  CiWRKYs  were unevenly distributed on 16 chromosomes, the largest number of genes on chromosome 3. Based on phylogenetic analysis, the 89 putative  CiWRKYs  could be classified into three major groups. The  CiWRKY  genes shared similar exon-intron distribution, and conserved motifs within the same subgroups. Expression profiles indicated that  CiWRKY16 ,  CiWRKY30 ,  CiWRKY42 ,  CiWRKY62 , and  CiWRKY69  genes were involved in flower differentiation and development, and majority of  CiWRKYs  genes were differentially expressed during embryo development. The present study provides reference for further comparative genomics and functional studies of this important class of transcriptional regulators in pecan.

Вплив грунтово-кліматичних умов на урожайність суниці садової (Fragaria ananassa L.)

Modern climate changes pose new challenges to scientists. Dry springs and low-snow winters negatively affect the development and fruiting of berry crops. Therefore, the breeding of new strawberry varieties, favorable to the new climatic conditions, is timely. On the basis of the Sumy Research Station of Horticulture, the factors that positively affect the development and fruiting of garden strawberries, in particular soil and climatic factors, were studied. Of the climatic factors for berry crops, the most important are heat and moisture supply during the growing season, overwintering conditions, harsh temperature fluctuations in summer and winter, low minimum temperatures, spring frosts and their frequency of recurrence and droughts, as well as soil conditions, which are harmful to fruit crops. To avoid diseases of the root system, it is recommended to avoid heavy clay soils. In conditions of high humidity and poor air access, plants are more vulnerable. Even if it rains, strawberries need watering during the phases of flowering, crop formation, berry picking and bud differentiation. The conducted phenological observations of the studied strawberry varieties showed that the beginning of flowering and ripeness of the varieties ‘Rosana Kyivska’, ‘Olvia’ depend on the beginning of the vegetation period. The yield was determined by weighing at each fruit collection in all areas of the experiment. The yield of mid-early varieties ‘Sonata’ and ‘Giant Journe’y in 2023 was negatively affected by frosts in May on the surface of the soil -1 0С, which damaged 10 % of the flowering plants. Covering with a white cloth and using soil mulching with a black film accelerated the growth of berries. The drip irrigation system even during the dry Mays of 2022-2023 with the amount of precipitation (30 mm) and (16.8 mm) made it possible to obtain a high yield of ‘Prestige’ (11.5 t/ha) and ‘Rainbow’ (11.9 t/ha). Studies have shown that growing garden strawberries under more controlled conditions accelerates plant development, maturity and achieves higher yields than under normal conditions. Key words: garden strawberry, climatic conditions, productivity, culture, variety, soil.

The role of phytohormones and their related miRNAs in sex differentiation of Xanthoceras sorbifolium Bunge

• Determined the influence of IAA, GA, ABA, ZT on sex differentiation of Xanthoceras sorbifolium . • Identified 20 significantly differently expressed miRNAs (83 miRNA/target pairs) being related to phytohormone synthesis and signal transduction during sex differentiation. Xanthoceras sorbifolium Bunge is an important woody oilseed tree in north China. However, its yield is severely restricted by a low ratio of female to male flowers, and little is known about the physiological and molecular mechanisms underlying the sex differentiation of flowers. Therefore, carrying out the research in its sex differentiation regulation mechanism is the basis of increasing seed yield. Here, we investigated the cytology of sex differentiation, the content and their ratios of indole-3-acetic acid (IAA), gibberellins (GA 3 ), zeatin (ZT), abscisic acid (ABA), the effects of plant growth regulators on flower development, and the expression profiles of phytohormone-related miRNAs. The results showed that both functional female and male flowers were bisexual at the early stage of flower bud differentiation, while the development of the pistils of male flowers and the stamens of female flowers was arrested at later stage of sex differentiation. Furthermore, IAA, ABA and ZT were shown to be beneficial to pistil development in X. sorbifolium . GA 3 was the key phytohormone in pistil abortion. High level of ABA/ZT was beneficial for microspore mother cell meiosis. ZT/IAA was probably related to pistil abortion. High level of ZT/GA 3 contributed to ovule development. Spraying 6-BA was more effective than GA 3 in increasing female-to-male ratio regardless of CK. In addition, several miRNAs played key roles in sex differentiation, especially miR393, miR396, and miR399. They participated in the regulation of pollen maturation and multiple phytohormone pathways. The present study comprehensively identified the roles of phytohormones and their related miRNAs during sex differentiation in X. sorbifolium , which will be a valuable resource for sex regulation using genetic and physiological methods in the future.

Metabolic analysis of the regulatory mechanism of sugars on secondary flowering in Magnolia

BackgroundMagnolia, a traditional and important ornamental plant in urban greening, has been cultivated for about 2000 years in China for its elegant flower shape and gorgeous flower color. Most varieties of Magnolia bloom once a year in spring, whereas a few others, such as Magnolia liliiflora Desr. ‘Hongyuanbao’, also bloom for the second time in summer or early autumn. Such a twice flowering trait is desirable for its high ornamental value, while its underlying mechanism remains unclear.MethodsParaffin section was used to show the flowering time and phenotypic changes of M. liliiflora ‘Hongyuanbao’ during the twice flowering periods from March 28 to August 25, 2018. Gas chromatography-mass spectrometry (GC-MS) was then performed to explore the chemical metabolites through the twice flower bud differentiation process in ‘Hongyuanbao’, and the metabolites were screened and identified by orthogonal projection to latent structures discriminant analysis (OPLS-DA). Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis (KEGG) was used to reveal the relationship between the sugar metabolites and twice-flowering characteristic. To further investigate the potential role of sucrose and trehalose on flowering regulation of ‘Hongyuanbao’, the plants once finished the spring flowering were regularly sprayed with sucrose and trehalose solutions at 30 mM, 60 mM, and 90 mM concentrations from April 22, 2019. The flower bud differentiation processes of sprayed plants were observed and the expression patterns of the genes involved in sucrose and trehalose metabolic pathways were studied by quantitative reverse transcription PCR (qRT-PCR).ResultsIt showed that ‘Hongyuanbao’ could complete flower bud differentiation twice in a year and flowered in both spring and summer. The metabolites of flower bud differentiation had a significant variation between the first and second flower buds. Compared to the first flower bud differentiation process, the metabolites in the sucrose and trehalose metabolic pathways were significantly up-regulated during the second flower bud differentiation process. Besides that, the expression levels of a number of trehalose-6-phosphate synthase (TPS) genes including MlTPS1, MlTPS5, MlTPS6, MlTPS7 and MlTPS9 were substantially increased in the second flower differentiation process compared with the first process. Exogenous treatments indicated that compared to the control plants (sprayed with water, CK), all three concentrations of trehalose could accelerate flowering and the effect of 60 mM concentration was the most significant. For the sucrose foliar spray, only the 60 mM concentration accelerated flowering compared with CK. It suggested that different concentration of trehalose and sucrose might have different effects. Expression analysis showed that sucrose treatment increased the transcription levels of MlTPS5 and MlTPS6, whereas trehalose treatment increased MlTPS1, showing that different MlTPS genes took part in sucrose and trehalose metabolic pathways respectively. The expression levels of a number of flowering-related genes, such as MlFT, MlLFY, and MlSPL were also increased in response to the sprays of sucrose and trehalose.ConclusionsWe provide a novel insight into the effect of sucrose and trehalose on the flowering process in Magnolia. Under the different sugar contents treatments, the time of flower bud differentiation of Magnolia was advanced. Induced and accelerated flowering in response to sucrose and trehalose foliar spray, coupled with elevated expression of trehalose regulatory and response genes, suggests that secondary flower bud formation is a promoted by altered endogenous sucrose and trehalose levels. Those results give a new understanding of sucrose and trehalose on twice-flowering in Magnolia and provide a preliminary speculation for inducing and accelerating the flowering process in Magnolia.