Hempel , F. This site. Google Scholar. Weigel , D. Mandel , M. Ditta , G. Zambryski , P. Feldman , L. Yanofsky M. Author and article information. Online Issn: Development 19 : — Cite Icon Cite. Light quality and vernalization interact in controlling late flowering in Arabidopsis ecotypes and mutants. Search ADS. Design in Arabidopsis thaliana of a synchronous system of floral induction by one long day.
Flowering responses to light breaks in photomorphogenic mutants of Arabidopsis thaliana, a long-day plant. Bi-directional inflorescence development in Arabidopsis thaliana: Acropetal initiation of flowers and basipetal initiation of paraclades.
GUS fusions:-glucuronidase as a sensitive and versatile gene fusion marker in higher plants. A genetic and physiological analysis of late flowering mutants in Arabidopsis thaliana. Floral determination in the terminal bud of the short-day plant Pharbitis nil. Effect of light quality and vernalization on late-flowering mutants of Arabidopsis thaliana. Floral determination and in-vitro floral differentiation in isolated shoot apices of Lolium temulentum L.
Molecular evolution of flower development: Diversification of the plant MADS-box regulatory gene family. When the higher plant changes from vegetative to reproductive growth, a new set of structures, the flower, is formed and represents the expression of genes not previously expressed.
The formation of sepals, petals, stamens, and carpels occurs nowhere else in the plant and meiosis occurs only in the stamens and carpels. The transition to flowering , therefore, represents a change in determination of the shoot apical cells and their derivatives. In a vegetative plant already competent to flower ripe-to-flower , only a change in determination would be required. A lack of competence to flower is most clearly seen in those plants that show a juvenile phase, i. Remembering that competence may be defined as the ability to develop along a particular pathway when given the appropriate signal, plants that flower in response to photoperiod , in which a signal is received from the leaves, may be regarded as competent to flower.
In such plants, the leaves are obviously competent to form the floral stimulus, but they may not be in some juvenile plants. Furthermore, it is often far from clear whether this signal from the leaves first has to make the apical meristem competent to flower or whether the meristem is already competent to flower but simply lacks the signal for determination. Unable to display preview.
Download preview PDF. Skip to main content. This service is more advanced with JavaScript available. Advertisement Hide. Competence and determination in flowering. Authors Authors and affiliations R. At stage 10, the highly stained anthers differentiated and all anther cell types were present including the endothecium, middle layer, tapetum, and microspore mother cells of the locules Figure 6C. At stage 11, the stamen underwent an increase in length ca.
Figure 6. Development of the androecium A—H and length of flower organs I in male and female flowers. A Stamen development at stage 8. B Appearance of anther and filament at stage 9. C Meiosis division occurred in locules of the anther at stage D More pollen grains were surrounded by tapetum at stage E,F Stage 8 and 9, respectively: the growth of staminode primordium was the same as in stages A,B.
G At stage 10, staminode development was blocked. H The staminode cells became vacuolated with sparse cytoplasm density. In contrast to the fertile stamens in male flowers, the staminodes in female flowers presented retarded growth. At stage 8 and stage 9, the staminode cells were densely stained and the anthers of the staminodes were differentiated. This was similar to the stamen development in male flowers at the same stage Figures 6E,F. However, compared with stamen development in male flowers, the staminodes displayed inconspicuous elongation and their development appeared to stop in stage 10 Figure 6I.
Meanwhile, the anther differentiated abnormally and microspore mother cells could not undergo meiosis to form microspores because of the disappearance of the tetrads in later development stages Figure 6G. During subsequent development, the staminode cells became vacuolated, the cell differentiation decreased, and the cytoplasm density gradually became sparse from the proximal to the distal region Figure 6H.
In summary, the staminode development was blocked during the development of the anther in stage 10 in the female flower, which led to the transformation of bisexual to unisexual characteristics in female flowers. In order to investigate the mechanism of androecium abortion, we mainly focused on staminode development in female flowers at the last three stages stages 9, 10, and The cellular changes in aborted staminodes were examined by staining paraffin-embedded tissue sections with DAPI Figure 7.
Figures 7A,B show that there were intact nuclei with bright DAPI staining from staminodes in the female flowers at stages 9 and As shown in Figure 7B , the anther of the staminode underwent differentiation to form a microspore mother cell of the locule with brighter and denser DAPI staining.
As the female flowers became mature, the staminodes presented nuclear loss in which diminished DAPI fluorescence was noted in subepidermal cells of the anther at stage 11 Figure 7C. Figure 7. At stage 11, nuclear loss arrowhead was displayed in subepidermal staminode cells C. Moreover, the distal anther cells were densely stained by PI, which was consistent with the results in Figure 7B. The lightness and density of the proximal-to-distal staminode nuclei gradually declined with DAPI and PI staining, indicating that the loss of nuclear integrity had increased.
In brief, the staminode abortion process was determined by cell death with a loss of nuclear integrity and DNA fragmentation in stage 11 during female flower development.
In order to investigate the molecular mechanisms responsible for the formation of unisexual flowers in V. In total, million clean reads were generated and each sample produced 16—36 million reads. A total of 56, unigenes was assembled with an average length of 1, bp and N50 of 1, bp. The number of unigenes with over bp was Based on the GO annotations, 21, Meanwhile, 8, They were found to be predominantly involved in the metabolic pathway, biosynthesis of secondary metabolites, ubiquitin-mediated proteolysis, plant hormone signal transduction, and the cell cycle Figure S3.
A total of and DEGs showed significant expression in male and female flowers, respectively. GO enrichment analysis was performed to reveal significant GO terms classified under three categories Table 1 , Table S3. In addition, an overview MapMan analysis showed that most of the different sexual genes were involved in hormone metabolism, development, stress, cell wall, transport, stress, and signaling Table S4. In the hormone category, jasmonic acid JA synthesis genes were significantly expressed in female flowers, which was consistent with the GO enrichment analysis.
Interestingly, the genes for photosynthesis, the Calvin cycle, minor CHO metabolism, and glycolysis related genes were specifically expressed in male flowers, which may facilitate stamen development.
Table 1. These genes are involved in plant organ growth, abscisic acid ABA response, gibberellin degradation, auxin transport, and JA synthesis.
In this study, 28 genes related to transcription factors TFs were significantly expressed in females Table S7. Compared with male flowers at stage 7, morphological divergence in females consisted of the continuous differentiation of the central dome into the gynoecium, which meant that some genes associated with the floral meristem were specifically expressed in females Table S8. We observed that the differentiation of inflorescences occurred between July and August in the current growing season in Hefei, which is different from the period between May 10 and October 1 reported in previous studies in Florida Abbott, The variation in differentiation time may depend on the nutrition level, cultivation, and environmental conditions.
For example, high soil moisture can delay the differentiation of inflorescences Abbott, The development of inflorescences started from July and lasted until April of the following year Figure 1. Similarly, this long period of inflorescence bud development can be seen in many species, such as pistachio Pistacia vera , Chinese ixora Ixora chinensis , and apples Malus domestica Golan-Goldhirsh et al. Although both V. Typically, female flowers are located at the center of the main or secondary axes, which are closed in many male flowers.
This facilitates self-pollination and the generation of homozygous progeny for several successive generations, which could further assist cultivar improvement and genetic study Potter, Histological and SEM analyses showed that the first divergence of sexual differences emerged at stage 7 and from Figures 3A , 4A , we could demonstrate that the meristematic size in females ca.
We postulated that some genes could directly regulate proper flower development and meristematic activity. According to the classical ABC model, class B, and class C genes collectively define stamens identity; class C genes alone determine formation of carpels Coen and Meyerowitz, ; Weigel and Meyerowitz, And the class C gene Agamous in V.
The SAM niche comprises undifferentiated and dividing stem cells that maintain the plant meristem and can differentiate to form new organs Galli and Gallavotti, Next, we focused on the exact morphological and cellular changes in the staminode of female flowers with a detailed histological analysis Figure 6.
The data indicated that at an early stage, the staminode continued to differentiate into the anthers with a bilobal stage and the development of short, non-elongated filaments. In stage 10, the sporogenous cell underwent mitosis, forming microspore mother cells with great bulk, large nuclei, and dense cytoplasm. Subsequently, the anthers degenerated and the microspore mother cells did not differentiate into microspores through meiosis at the floral stage 10, which was recognized as the pre-meiosis stage.
Similarly, the arrest of the staminodes can occur at any stage of development in other diclinous species, such as, at the initiation of the stamen primordia in P. There are two predominant developmental processes for inappropriate sex organ arrest in unisexual flowers: cell cycle block and cell death Diggle et al. Developmental studies revealed that the arrest of staminodes in V.
In maize, pistil abortion in the tassel and secondary ear is associated with cell death mediated by Tasselseed1 and tasselseed2 , whereas stamen arrest in ear spikelets is involved in cell cycle block Calderon-Urrea and Dellaporta, ; Kim et al. Thus, a great variety of developmental arrest stages and processes suggest that each species has independent genetic mechanisms that control inappropriate sex organs under unisexual flower development.
However, the genetic mechanisms underlying the developmental abortion of the staminode in V. Phytohormones play important roles in flower development, especially in sex determination Tanurdzic and Banks, Comparative transcriptome analysis showed that the expression of some genes involved in auxin, cytokinin, ethylene, gibberellin, and ABA biosynthesis was significantly changed. However, GO term enrichment demonstrated that some DEGs involved in JA biosynthesis were significantly enriched in female flowers, suggesting that JA could play crucial roles in the sex determination process in V.
In Arabidopsis, LOX2 is highly expressed in inflorescences and contributes to the majority of jasmonate synthesis Bell and Mullet, Lox3 lox4 double mutants display more inflorescence shoots and flowers with carpelloid and staminode structures Caldelari et al. As in tomato Lycopersicon esculentum , jasmonic acid - insensitive 1 jai1 mutants defective in JA signaling exhibit a defect in the maternal process of seed production, which indicates that JA also plays an important role in female fertility Li et al.
However, JA is a positive regulator in the stamen development of the tassels in maize that alter sex determination. Tasselseed1 mutants display pistil development of the primary and secondary florets in both ears as well as tassels with no stamen development and stamen development can be rescued by the application of exogenous JA Irish et al.
The roles of JA in maize, Arabidopsis and tomato demonstrate that JA regulates distinct developmental processes in different species. We propose that JA triggers tissue- or cell-specific signaling to reprogram the differentiation of the gynoecium for the sexual dimorphism of female flowers in V.
GL3 was up-regulated in female flowers and is involved in the JA response and cell fate Yoshida et al. In conclusion, the present study provides a detailed description of V. Based on transcriptomic analysis of male and female flowers in V. Some genes associated with the JA biosynthesis pathway and JA metabolic processes were significantly modified in female flowers.
Additionally, a number of the TFs responded to JA signaling and triggered extensive transcriptional reprogramming on the floral meristem in V. These data provide deeper insights to study the processes of sex determination in V. YM and LW conceived and designed the experiments. YM and WBL performed the histological analysis. YM analyzed sequencing data. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
Figure S1. The distribution and proportion of all assembled contig lengths. Figure S2. Gene ontology GO classification for all assembled unigenes using SuperViewer tool with normalized results. Figure S4. Table S2. The genes differentially expressed between male and female flowers in stage 7. Table S3. GO term enrichment analyses of male left and female right flowers in V.
Table S4. Functional categories of differentially expressed genes assigned by MapMan. Table S5. Table S6. Genes enriched to GO term related to JA in female flowers. Table S7. Genes related to transcription factors in male and female flowers. Table S8. Genes related to floral meristem in female flowers. Abbott, C. Fruit-bud development in tire tung-oil tree.
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