The morphology, ultrastructure, element distribution and motion behaviour in pollen of Ginkgo biloba L.

Lu, Yan; Zhang, Li; Cheng, Fangmei; Zhao, Jianguo; Cui, Jiawen; Li, Weixing; Wang, Li; Jin, Biao

doi:10.1007/s00468-016-1444-z

Cited by 12 publications

(6 citation statements)

References 35 publications

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“…The dried samples were mounted in metal stubs and sputter coated (Bal-Tec, Balzers, Switzerland) with a thin conductive film of gold. The coated samples were examined and photographed using scanning electron microscopy (SEM) (Hitachi High-Technologies Corporation, Tokyo, Japan) at 15.0 kV [27]. The average area of stomatal opening was calculated from at least 40 stomata using ImageJ software (V1.51; National Institutes of Health, Bethesda, MD, USA).…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

Transcriptomic and Metabolomic Analysis of the Heat-Stress Response of Populus tomentosa Carr.

Ren

et al. 2019

Forests

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Plants have evolved mechanisms of stress tolerance responses to heat stress. However, little is known about metabolic responses to heat stress in trees. In this study, we exposed Populus tomentosa Carr. to control (25 °C) and heat stress (45 °C) treatments and analyzed the metabolic and transcriptomic effects. Heat stress increased the cellular concentration of H2O2 and the activities of antioxidant enzymes. The levels of proline, raffinose, and melibiose were increased by heat stress, whereas those of pyruvate, fumarate, and myo-inositol were decreased. The expression levels of most genes (PSB27, PSB28, LHCA5, PETB, and PETC) related to the light-harvesting complexes and photosynthetic electron transport system were downregulated by heat stress. Association analysis between key genes and altered metabolites indicated that glycolysis was enhanced, whereas the tricarboxylic acid (TCA) cycle was suppressed. The inositol phosphate; galactose; valine, leucine, and isoleucine; and arginine and proline metabolic pathways were significantly affected by heat stress. In addition, several transcription factors, including HSFA2, HSFA3, HSFA9, HSF4, MYB27, MYB4R1, and bZIP60 were upregulated, whereas WRKY13 and WRKY50 were downregulated by heat stress. Interestingly, under heat stress, the expression of DREB1, DREB2, DREB2E, and DREB5 was dramatically upregulated at 12 h. Our results suggest that proline, raffinose, melibiose, and several genes (e.g., PSB27, LHCA5, and PETB) and transcription factors (e.g., HSFAs and DREBs) are involved in the response to heat stress in P. tomentosa.

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Section: Scanning Electron Microscopymentioning

confidence: 99%

Transcriptomic and Metabolomic Analysis of the Heat-Stress Response of Populus tomentosa Carr.

Ren

et al. 2019

Forests

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“…They were then rinsed three times in 0.1 M phosphate buffer (15 min per rinse), dehydrated in a graded ethanol series (30, 50, 70, 80, 90, 95, and 100%; 15 min each), and dried by automatic critical point drying (Leica, Wetzlar, Germany). After sputter coating (Bal-Tec, Balzers, Switzerland), the samples were examined, imaged, and measured by scanning electron microscopy (SEM) (Hitachi High-Technologies Corporation, Tokyo, Japan) at 15.0 kV [ 20 ]. Petal cell size measurements under SEM were based on three samples selected randomly at each stage.…”

Section: Methodsmentioning

confidence: 99%

miRNAs involved in the development and differentiation of fertile and sterile flowers in Viburnum macrocephalum f. keteleeri

Zhang

et al. 2017

BMC Genomics

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BackgroundSterile and fertile flowers are important evolutionary developmental phenotypes in angiosperm flowers. The development of floral organs, critical in angiosperm reproduction, is regulated by microRNAs (miRNAs). However, the mechanisms underpinning the miRNA regulation of the differentiation and development of sterile and fertile flowers remain unclear.ResultsHere, based on investigations of the morphological differences between fertile and sterile flowers, we used high-throughput sequencing to characterize the miRNAs in the differentiated floral organs of Viburnum macrocephalum f. keteleeri. We identified 49 known miRNAs and 67 novel miRNAs by small RNA (sRNA) sequencing and bioinformatics analysis, and 17 of these known and novel miRNA precursors were validated by polymerase chain reaction (PCR) and Sanger sequencing. Furthermore, by comparing the sequencing results of two sRNA libraries, we found that 30 known and 39 novel miRNA sequences were differentially expressed, and 35 were upregulated and 34 downregulated in sterile compared with fertile flowers. Combined with their predicted targets, the potential roles of miRNAs in V. macrocephalum f. keteleeri flowers include involvement in floral organogenesis, cell proliferation, hormonal pathways, and stress responses. miRNA precursors and targets were further validated by quantitative real-time PCR (qRT-PCR). Specifically, miR156a-5p, miR156g, and miR156j expression levels were significantly higher in fertile flowers than in sterile flowers, while SPL genes displayed the opposite expression pattern. Considering that the targets of miR156 are predicted to be SPL genes, we propose that miR156 may be involved in the regulation of stamen development in V. macrocephalum f. keteleeri. ConclusionsWe identified miRNAs differentially expressed between fertile and sterile flowers in V. macrocephalum f. keteleeri and provided new insights into the important regulatory roles of miRNAs in the differentiation and development of fertile and sterile flowers.Electronic supplementary materialThe online version of this article (10.1186/s12864-017-4180-x) contains supplementary material, which is available to authorized users.

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“…Water not only captures and hydrates pollen, but in many species, e.g., Cupressus arizonica (Chichiriccò et al, 2009), and G. biloba (Lu et al, 2016), water also causes pollen to shed its exine layer. This is an important event prior to germination.…”

Section: Modern Gymnospermsmentioning

confidence: 99%

“…Calcium is important for pollen germination (Brewbaker and Kwack, 1963). Recent studies have shown it to be present in Ginkgo pollen intine (Lu et al, 2016). Phosphate was identified long ago in pollination drops of T. baccata and E. distachya ( Ziegler, 1959), but the form of phosphate was not established.…”

Section: Modern Gymnospermsmentioning

confidence: 99%

“…Active processes are thought to occur in two steps, the first of which involves pollen hydration and loss of its exine. The next step–active retraction–occurs as the pollen sinks into the drop (Lu et al, 2016). One family of conifers–Cupressaceae– is noteworthy in the rapidity with which pollination drop retraction takes place following pollination.…”

Section: Drop Dynamicsmentioning

confidence: 99%

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The Evolution of Sexual Fluids in Gymnosperms From Pollination Drops to Nectar

2018

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A current synthesis of data from modern and fossil plants paints a new picture of sexual fluids, including nectar, as a foundational component of gymnosperm reproductive evolution. We review the morpho-anatomical adaptations, their accompanying secretions, and the functional compounds involved. We discuss two types of secretions: (1) those involved in fertilization fluids produced by gametophytes and archegonia of zooidogamous gymnosperms, i.e., Ginkgo and cycads, and (2) those involved in pollen capture mechanisms (PCMs), i.e., pollination drops. Fertilization fluids provide both liquid in which sperm swim, as well as chemotactic signals that direct sperm to the egg. Such fertilization fluids were probably found among many extinct plants such as ancient cycads and others with swimming sperm, but were subsequently lost upon the evolution of siphonogamy (direct delivery of sperm to the egg by pollen tubes), as found in modern gnetophytes, conifers, and Pinaceae. Pollination drops are discussed in terms of three major types of PCMs and the unique combinations of morphological and biochemical adaptations that define each. These include their amino acids, sugars, calcium, phosphate and proteins. The evolution of PCMs is also discussed with reference to fossil taxa. The plesiomorphic state of extant gymnosperms is a sugar-containing pollination drop functioning as a pollen capture surface, and an in ovulo pollen germination medium. Additionally, these drops are involved in ovule defense, and provide nectar for pollinators. Pollination drops in anemophilous groups have low sugar concentrations that are too low to provide insects with a reward. Instead, they appear to be optimized for defense and microgametophyte development. In insect-pollinated modern Gnetales a variety of tissues produce sexual fluids that bear the biochemical signature of nectar. Complete absence of fluid secretions is restricted to a few, poorly studied modern conifers, and is presumably derived. Aspects of pollination drop dynamics, e.g., regulation of secretion and retraction, are reviewed. Lastly, we discuss pollination drops’ control of pollen germination. Large gaps in our current knowledge include the composition of fertilization fluids, the pollination drops of Podocarpaceae, and the overall hydrodynamics of sexual fluids in general.

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The morphology, ultrastructure, element distribution and motion behaviour in pollen of Ginkgo biloba L.

Cited by 12 publications

References 35 publications

Transcriptomic and Metabolomic Analysis of the Heat-Stress Response of Populus tomentosa Carr.

Transcriptomic and Metabolomic Analysis of the Heat-Stress Response of Populus tomentosa Carr.

miRNAs involved in the development and differentiation of fertile and sterile flowers in Viburnum macrocephalum f. keteleeri

The Evolution of Sexual Fluids in Gymnosperms From Pollination Drops to Nectar

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