Development of the Male Gametophyte of Ginkgo biloba: A Window into the Reproductive Biology of Early Seed Plants

1997 ◽  
pp. 29-49 ◽  
Author(s):  
William E. Friedman ◽  
Ernest M. Gifford
Keyword(s):  
Reproductive Biology ◽  
Ginkgo Biloba ◽  
Male Gametophyte ◽  
Seed Plants

scholarly journals The Arabidopsis V-ATPase is localized to the TGN/EE via a seed plant specific motif and acts in a partially redundant manner with the tonoplast enzyme

2020 ◽  
Author(s):  
Upendo Lupanga ◽  
Rachel Röhrich ◽  
Jana Askani ◽  
Stefan Hilmer ◽  
Christiane Kiefer ◽  
...  
Keyword(s):  
Male Gametophyte ◽  
Site Directed Mutagenesis ◽  
Null Alleles ◽  
Marchantia Polymorpha ◽  
Seed Plants ◽  
Proton Pumps ◽  
Intracellular Compartments ◽  
A Subunit ◽  
Er Export ◽  
Golgi Network

AbstractVacuolar-type H+-ATPases (V-ATPases) are versatile proton pumps that control the pH of many intracellular compartments in all eukaryotic cells. The localization of the Arabidopsis V-ATPase was previously shown to be determined by the isoforms of subunit a (VHA-a). The incorporation of VHA-a1 targets the V-ATPase to the trans-Golgi network/early endosome (TGN/EE) whilst the incorporation of VHA-a2 or VHA-a3 targets the V-ATPase to the tonoplast. By employing chimeric proteins and site directed mutagenesis we identified a targeting domain (a1-TD) containing an acidic cluster in the N-terminus of VHA-a1 that serves as both an ER export signal and as a TGN retention motif. The a1-TD is conserved among seed plants and we confirmed experimentally that its presence is predictive of TGN/EE- localization. In contrast to many other non-seed plants, the liverwort Marchantia polymorpha encodes only a single VHA-a subunit (MpVHA-a) and we show here that it is predominantly localized at the tonoplast. In our attempts to determine if MpVHA-a can functionally replace the Arabidopsis VHA-a isoforms, we used CRISPR/Cas9 to generate null-alleles lacking VHA-a1 and discovered that its function is essential for male gametophyte development but can be replaced by VHA-a2 and VHA-a3 during vegetative growth.

scholarly journals The Arabidopsis V-ATPase is localized to the TGN/EE via a seed plant-specific motif

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Upendo Lupanga ◽  
Rachel Röhrich ◽  
Jana Askani ◽  
Stefan Hilmer ◽  
Christiane Kiefer ◽  
...  
Keyword(s):  
Proton Pump ◽  
Vegetative Growth ◽  
Male Gametophyte ◽  
Functional Redundancy ◽  
Evolutionary Origin ◽  
Null Alleles ◽  
Seed Plants ◽  
Seed Plant ◽  
Gametophyte Development ◽  
Essential Function

The V-ATPase is a versatile proton-pump found in a range of endomembrane compartments yet the mechanisms governing its differential targeting remain to be determined. In Arabidopsis, VHA-a1 targets the V-ATPase to the TGN/EE whereas VHA-a2 and VHA-a3 are localized to the tonoplast. We report here that the VHA-a1 targeting domain serves as both an ER-exit and as a TGN/EE-retention motif and is conserved among seed plants. In contrast, Marchantia encodes a single VHA-isoform that localizes to the TGN/EE and the tonoplast in Arabidopsis. Analysis of CRISPR/Cas9 generated null alleles revealed that VHA-a1 has an essential function for male gametophyte development but acts redundantly with the tonoplast isoforms during vegetative growth. We propose that in the absence of VHA-a1, VHA-a3 is partially re-routed to the TGN/EE. Our findings contribute to understanding the evolutionary origin of V-ATPase targeting and provide a striking example that differential localization does not preclude functional redundancy.

scholarly journals A physiologically explicit morphospace for tracheid-based water transport in modern and extinct seed plants

Paleobiology ◽  
2010 ◽  
Vol 36 (2) ◽  
pp. 335-355 ◽  
Author(s):  
Jonathan P. Wilson ◽  
Andrew H. Knoll
Keyword(s):  
Hydraulic Resistance ◽  
Water Transport ◽  
Morphometric Analysis ◽  
Ginkgo Biloba ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Seed Plants ◽  
Seed Plant ◽  
Evolutionary Time ◽  
Three Dimensional Space

We present a morphometric analysis of water transport cells within a physiologically explicit three-dimensional space. Previous work has shown that cell length, diameter, and pit resistance govern the hydraulic resistance of individual conducting cells; thus, we use these three parameters as axes for our morphospace. We compare living and extinct plants within this space to investigate how patterns of plant conductivity have changed over evolutionary time. Extinct coniferophytes fall within the range of living conifers, despite differences in tracheid-level anatomy. Living cycads, Ginkgo biloba, the Miocene fossil Ginkgo beckii, and extinct cycadeoids overlap with both conifers and vesselless angiosperms. Three Paleozoic seed plants, however, occur in a portion of the morphospace that no living seed plant occupies. Lyginopteris, Callistophyton, and, especially, Medullosa evolved tracheids with high conductivities similar to those of some vessel-bearing angiosperms. Such fossils indicate that extinct seed plants evolved a structural and functional diversity of xylem architectures broader, in some ways, than the range observable in living seed plants.

Reproductive Biology in Early Seed Plants

BioScience ◽  
1982 ◽  
Vol 32 (1) ◽  
pp. 23-28 ◽  
Author(s):  
Thomas N. Taylor
Keyword(s):  
Reproductive Biology ◽  
Seed Plants

Fine structure and possible functions of the hermaphrodite duct of some pulmonate snails (Mollusca: Gastropoda)

1990 ◽  
Vol 48 (3) ◽  
pp. 68-69
Author(s):  
Alan N. Hodgson
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Seminal Vesicle ◽  
Reproductive Biology ◽  
Light Microscope ◽  
Light Microscope Level ◽  
Transmission Electron ◽  
Standard Techniques

The hermaphrodite duct of pulmonate snails connects the ovotestis to the fertilization pouch. The duct is typically divided into three zones; aproximal duct which leaves the ovotestis, the middle duct (seminal vesicle) and the distal ovotestis duct. The seminal vesicle forms the major portion of the duct and is thought to store sperm prior to copulation. In addition the duct may also play a role in sperm maturation and degredation. Although the structure of the seminal vesicle has been described for a number of snails at the light microscope level there appear to be only two descriptions of the ultrastructure of this tissue. Clearly if the role of the hermaphrodite duct in the reproductive biology of pulmonatesis to be understood, knowledge of its fine structure is required.Hermaphrodite ducts, both containing and lacking sperm, of species of the terrestrial pulmonate genera Sphincterochila, Levantina, and Helix and the marine pulmonate genus Siphonaria were prepared for transmission electron microscopy by standard techniques.

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