A Possible Role for the Endoplasmic Reticulum in Exine Formation

Gabara, B.

doi:10.1080/00173137409434769

Cited by 9 publications

(4 citation statements)

References 20 publications

(5 reference statements)

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“…In the plasma of the tapetal cell in the ER cisternae electron-dense globules are developed. This process is observed in the tapetal cells of Allium and Pinus (RISUENO et al 1969;WILLEMSE 1971) and in microspores of Berberis (GABARA 1974), where the globules are involved in the formation of the exine. They probably stick to the orbicules too.…”

Section: Function Of the Tapetal Cell And Formation Of Orbiculesmentioning

confidence: 95%

Formation of Pollen in the Anther of Lilium Ii. The Function of the Surrounding Tissues in the Formation of Pollen and Pollen Wall

Reznickova¹,

Willemse²

1980

Acta Botanica Neerlandica

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IntheLilium anther a peritapetal andtapetal membrane aremade bythe tapetal cells. During the young microspore stage thepro-orbicules receive a matrix ofmainly carbohydrates similar to thatof the sexine. The plasma-membrane of the tapetal cells forms membrane-like lamellae. During the vacuolization of the microspore the orbicule diameter increases. In the channels made by the endoplasmic reticulum theglobules ofsporopollenin areproduced. Thelipid inclusions accumulate and globules containing carotenoid increase in the plastids. Both elements fuse and form the "Pollenkitt" during degeneration of thetapetal cell. Some sporopollenin globules fuse and form a second generation of orbicules. Thecell of the middle layer next to the tapetal cell contains lipid granules. Theotherfourcells ofthemiddle layer lose their starch at thestage oftheyoung microspore and after mitosis thelipid granules areproduced. Asa source fornutrients intheloculus thestarch of the middle layer cells hasan important function. Aninteraction model isschematically presented.

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Section: Function Of the Tapetal Cell And Formation Of Orbiculesmentioning

confidence: 95%

Formation of Pollen in the Anther of Lilium Ii. The Function of the Surrounding Tissues in the Formation of Pollen and Pollen Wall

Reznickova¹,

Willemse²

1980

Acta Botanica Neerlandica

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“…In Berberis ridgaris (Gabara 1974) the primexine and most of the exine development occurred while the microspores were enclosed in callose. Callose is not present around the SMCs or the meiotic products in homosporous pteridophytes (Bienfait & Waterkeyn 1976, Lugardon 1971, Pettitt 19790, Uehara & Kurita 1989b, Waterkeyn & Bienfait 1971.…”

Section: Discussionmentioning

confidence: 99%

Spore Wall Development inSchizaea Pectinata(Schizaeaceae: Pteridophyta)

Parkinson¹

1995

Grana

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A blechnoid type of spore wall developed in Scltizaeapecrinaru (L.) Sw. consisting of inner and outer exospore, inner and outer perispore. The inner exospore was initiated by the formation of electron dense lamellae from the surface of the plasma membrane around each member of the tetrad. Tetnds were enclosed within chambers in the plasmodia1 tapetum. The outer exospore constituted the bulk of the spore wall and accumulated, at first. in irregular patches on the inner exospore; its deposition involved the activity of the plasma membrane of the plasmodial tapetum. A reticulate pattern developed on the outer exospore as a result of a differential pattern of growth involving plasmodia1 tapetum activity. The heterogeneous inner perispore was firmly attached to the outer exospore and its deposition involved structures found in the sporangial loculus. The outer perispore was loosely attached to the inner perispore and its formation was associated with composite bodies, which differed from the structures involved in inner perispore development, and consisted of partially polymerised sporopollenin, phenolics and silicon particles. Only the initiation of the inner exospore involved sporal activity, the development of the other parts of the spore wall were intimately associated with the plasmodial tapetum and with bodies present in the sporangial loculus. There is a large amount of literature relating to microsporogenesis and the ontogeny of the angiosperm pollen grain but relatively little literature on spora! ontogeny of the pteridophytes in general and for the homosporous ferns in particular.The greatest contribution to early ultrastructural studies of sporogenesis within the pteridophytes was by Lugardon (1966Lugardon ( , 1968 on spore wall ontogeny and cytology in Bleclrtirriti spicnrif, Ostiiirtidn regnlis and Eqiiisetirtii itin.vitiziiiti. GullvAg ( 1970) compared events which occurred during the development of L~copodiirni oiriiotiriirtii spores with events which occurred during microsporogenesis in the angiosperms and Robert (1970, 1971 a, b) working on Selnginella krnirssinnn and S. selaginoides discussed the involvement of the tapetum in the formation of the spore wall. Lugardon (1971Lugardon ( , 1972 defined the terminology which he used in describing the various wall layers of pteridophyte spores. He was of the opinion that the sub-division of the exine, defined in terms of the organisation of this layer in pollen, could not be applied correctly to the layers of the exospore. From descriptions of spore wall structure in a wide selection of homosporous ferns (Lugardon 1974(Lugardon , 1975(Lugardon , 1976 he drew a comparison between pollen and pteridophyte'spore walls (Lugardon 1978). Lugardon's terminology has been applied to the spore wall layers in S. pecriiintn.Publications by Sheffeld & Bell (1979) on ultrastructural events during meiosis in Pferidiurn aqrriliriirm, by Lugardon (1979) on the formation of the spore wall from the tetrad stage in Psilotiitti and by Pettitt (19790) and cytochemical aspect...

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“…Thus, according to my suggestion, lipoproteins can be a link in the chain of sporopollenin biosynthesis, and these substances are probably synthesized by different forms of ER-aggregates, such as chain-mail ER in Michelia fuscata and Manglietici tenuipes (Gabarayeva 1990) and by ER-aggregates in Lirindendron chinense, or nonaggregated ER, such as tubular SER with ampoule-like dilatations at the late tetrad stage in Lirindendron chinense. Support for the involvment of lipoproteins has come from the study on exine formation of Berberis vulgaris, where a possible role of ERsynthesis of proteins or lipids was proposed for short RER cisternae which excreted osmiophilic globules seen later at the tetrad stage at the plasmalemma surface (Gabara 1974), and from a study on Lonicera where the tion of dilated RER with osmiophilic cytoplasmic inclusions was observed, and cytochemically tested inclusions showed both protein and lipid nature (Vishnjakova 1987).…”

Section: The Probable Function Of Er-aggregatesmentioning

confidence: 99%

“…The site of synthesis of sporopollenin precursors in the microspores had been attributed to different cell organelles, to cytoplasm with its ribosomes (Shoup et al 1980, Silene alba), or referred to as unclear (Vasil & Aldrich 1970, Podocarpus macrophyllus; Gabarayeva 1995, Anaxugorea brevipes). However, the preference is given to the endoplasmic reticulum (Gabara 1974. Berberis vulgaris ;Dickinson 1976a.…”

Section: Introductionmentioning

confidence: 99%

Sporoderm development in Liriodendron chinense (Magnoliaceae): a probable role of the endoplasmic reticulum

Gabarayeva

1996

Nordic Journal of Botany

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The developmental events in the sporoderm and the cytoplasm of Liriodendron chinense microspore from the early tetrad stage until late free microspore stage were observed. Various forms of the endoplasmic reticulum (ER) and surprising unusual aggregates of ER seen during microspore development attract special attention. Being scanty at early and middle tetrad stage, while primexine matrix (glycocalyx) acquires well‐defined form, the ER becomes distinct in unusual forms at the late tetrad stage. Thin long tubules with an osmiophilic contents, which cannot be compared with the tubular smooth endoplasmic reticulum (SER), undulate through the cytoplasm. Towards the end of the tetrad period when callose begins to disintegrate, and a distinct tectate‐columellate pattern of the ectexine becomes evident, two new forms of the SER occur in the cytoplasm. Instead of single tubules observed previously, 3–tubuled aggregates meander through the cytoplasm, the middle tubule contains an osmiophilic substance. The second form of the SER looks like an ordinary tubular SER, but has ampoule‐like dilations with dark granular contents. Later on the tubules undergo major changes: multi‐tubuled aggregates of parallel tubules overcrowd the cytoplasm, the outer tubules of each aggregate carrying ribosomes. These aggregates undulate through the cytoplasm, branch, and are associated with lipid globules. The tips of many aggregates are pressed to the plasmalemma. The ontogenetic period of time of the presence of these ER aggregates, their structure and localization in the microspore cytoplasm allow me to assume that these ER aggregates synthesize sporopollenin precursors.

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A Possible Role for the Endoplasmic Reticulum in Exine Formation

Cited by 9 publications

References 20 publications

Formation of Pollen in the Anther of Lilium Ii. The Function of the Surrounding Tissues in the Formation of Pollen and Pollen Wall

Formation of Pollen in the Anther of Lilium Ii. The Function of the Surrounding Tissues in the Formation of Pollen and Pollen Wall

Spore Wall Development inSchizaea Pectinata(Schizaeaceae: Pteridophyta)

Sporoderm development in Liriodendron chinense (Magnoliaceae): a probable role of the endoplasmic reticulum

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