Fine Structural Studies of Zea mays Pollen I: Cell Membranes and Exine Ontogeny

Skvarla, John J.; Larson, Donald A.

doi:10.2307/2440692

Cited by 115 publications

(93 citation statements)

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“…The maize microspore developmental pathway can be briefly summarized as follows (1, 3,6,21) (15). One-dimensional gels were stained with Coomassie blue, and two-dimensional gels were silverstrained (13).…”

Section: Methodsmentioning

confidence: 99%

Developmental Staging of Maize Microspores Reveals a Transition in Developing Microspore Proteins

Bedinger¹,

Edgerton²

1990

Plant Physiol.

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A method for the preparation of developmentally staged microspores and young pollen from maize (Zea mays) has been devised. The preparations are of sufficient purity and quantity for biochemical analysis, including the analysis of steady-state protein and RNA populations associated with each stage. A major transition in protein populations occurs during the developmental period that encompasses microspore mitosis, the asymmetric nuclear division producing the vegetative and generative nuclei. Several differences between early and late stage proteins can be detected by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two-dimensional gel electrophoresis of proteins reveals that over half of the steady-state proteins differ between the younger and older stages, either quantitative or qualitative. One protein that increases in relative abundance about fourfold is actin. In vitro translation of RNA isolated from staged microspores demonstrates changes in microspore gene expression during the same developmental period.acious remnants of the tapetal cells are deposited on the surface of the pollen grain, which desiccates and is shed from the anther upon dehiscence.The study of pollen development provides an opportunity to examine the gametophyte generation of higher plants. While recent studies have suggested that multiple molecular events are involved in the progression of microspores through the pollen developmental pathway (4,(23)(24)(25), the scope of these events was unknown. The work presented here provides a method for the preparation of developmentally staged microspores and young pollen. These preparations are of sufficient purity and quantity to allow the characterization of protein and RNA populations associated with each stage. A major transition in steady-state protein populations has been observed between the large vacuole and starch-filling stages of microsporogenesis. MATERIALS AND METHODS MaterialsMicrosporogenesis in higher plants has been well described at the genetic and cytological levels (1,2,9,11,20). The maize microspore developmental pathway can be briefly summarized as follows (1,3,6,21)

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Section: Methodsmentioning

confidence: 99%

Developmental Staging of Maize Microspores Reveals a Transition in Developing Microspore Proteins

Bedinger¹,

Edgerton²

1990

Plant Physiol.

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“…Although there have been a number of elegant morphological studies on pollen wall development (Skvarla and Larson, 1966;El-Ghazaly and Jensen, 1986), biochemical studies of this unique and highly specialized pollen structure are Only beginning. Exine purification has allowed the production of specific antibodies (Southworth, 1988;Southworth et al, 1988) and the first characterization of potential structural proteins (Chay et al, 1992).…”

Section: A Unique Cell Wallmentioning

confidence: 99%

The remarkable biology of pollen.

Bedinger

1992

Plant Cell

249

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“…Among these other species, maize (Zea mays) has been the most studied. Electron microscopy (EM) studies have shown that tapetum cells at a late developmental stage in maize do not possess elaioplasts and tapetosomes (Skvarla and Larson, 1966;Horner et al, 1993;this report), so the pollen-coat materials have to be synthesized, stored, and delivered via other mechanisms.…”

mentioning

confidence: 99%

The Maize Tapetum Employs Diverse Mechanisms to Synthesize and Store Proteins and Flavonoids and Transfer Them to the Pollen Surface

Suen

Huang

et al. 2012

Plant Physiology

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In anthers, the tapetum synthesizes and stores proteins and flavonoids, which will be transferred to the surface of adjacent microspores. The mechanism of synthesis, storage, and transfer of these pollen-coat materials in maize (Zea mays) differs completely from that reported in Arabidopsis (Arabidopsis thaliana), which stores major pollen-coat materials in tapetosomes and elaioplasts. On maize pollen, three proteins, glucanase, xylanase, and a novel protease, Zea mays pollen coat protease (ZmPCP), are predominant. During anther development, glucanase and xylanase transcripts appeared at a mid developmental stage, whereas protease transcript emerged at a late developmental stage. Protease and xylanase transcripts were present only in the anther tapetum of the plant, whereas glucanase transcript was distributed ubiquitously. ZmPCP belongs to the cysteine protease family but has no closely related paralogs. Its nascent polypeptide has a putative amino-terminal endoplasmic reticulum (ER)-targeting peptide and a propeptide. All three proteins were synthesized in the tapetum and were present on mature pollen after tapetum death. Electron microscopy of tapetum cells of mid to late developmental stages revealed small vacuoles distributed throughout the cytoplasm and numerous secretory vesicles concentrated near the locular side. Immunofluorescence microscopy and subcellular fractionation localized glucanase in ER-derived vesicles in the cytoplasm and the wall facing the locule, xylanase in the cytosol, protease in vacuoles, and flavonoids in subdomains of ER rather than in vacuoles. The nonoverlapping subcellular locations of the three proteins and flavonoids indicate distinct modes of their storage in tapetum cells and transfer to the pollen surface, which in turn reflect their respective functions in tapetum cells or the pollen surface.

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Fine Structural Studies of Zea mays Pollen I: Cell Membranes and Exine Ontogeny

Cited by 115 publications

References 0 publications

Developmental Staging of Maize Microspores Reveals a Transition in Developing Microspore Proteins

Developmental Staging of Maize Microspores Reveals a Transition in Developing Microspore Proteins

The remarkable biology of pollen.

The Maize Tapetum Employs Diverse Mechanisms to Synthesize and Store Proteins and Flavonoids and Transfer Them to the Pollen Surface

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