Premeiotic Microsporocyte Cell Shape Influences Shape of Tetrads during Microsporogenesis

Penet, Laurent

doi:10.1086/664716

Cited by 4 publications

(7 citation statements)

References 41 publications

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“…Irregular tetrads develop from elongate microsporocytes, whereas spherical microsporocytes mostly give rise to regular (decussate and tetragonal) tetrads. Irregular tetrads may thus not be teratological (Penet, ). The variation of microspore tetrad types in Scheuchzeria has never been observed before and no data on tetrad shape were previously available (Furness & Banks, ).…”

Section: Discussionmentioning

confidence: 99%

“…In most examined species, irregular tetrads occur at low frequencies. However, it has been shown for some species of Asparagales with successive cytokinesis that irregular tetrads can be produced at higher frequencies or even become the majority (Penet, ). Resulting tetrad shapes are influenced by microsporocyte shape (Penet, ).…”

Section: Discussionmentioning

confidence: 99%

“…However, it has been shown for some species of Asparagales with successive cytokinesis that irregular tetrads can be produced at higher frequencies or even become the majority (Penet, ). Resulting tetrad shapes are influenced by microsporocyte shape (Penet, ). Irregular tetrads develop from elongate microsporocytes, whereas spherical microsporocytes mostly give rise to regular (decussate and tetragonal) tetrads.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, terminology of tetrad types deserves further attention. For example, Penet () considered T‐shaped and linear tetrads as irregular. In our view, for plants with successive sporogenesis, the term ‘irregular tetrads’ should be used only for those tetrads in which one or both second divisions are oblique with respect to the plane of the first division.…”

Section: Discussionmentioning

confidence: 99%

“…Our results show a high frequency of irregular tetrads. Penet (2012) suggested that tetrad length-to-width ratio is close to the length-to-width ratio of the microspore mother cell. Considering tetrads illustrated in our Figure 5, we conclude that linear, Tshaped and irregular tetrads have greater length-towidth ratios.…”

Section: Diversity Of Tetrad Typesmentioning

confidence: 93%

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A developmental study of pollen dyads and notes on floral development inScheuchzeria(Alismatales: Scheuchzeriaceae)

et al. 2016

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Scheuchzeria palustris, the only member of Scheuchzeriaceae, is unique among Alismatales in several characters, including flower‐subtending bracts with conspicuous laminas and pollen dispersed in permanent dyads. Earlier studies revealed unidirectional flower development in some monocots with massive flower‐subtending bracts, but not in Scheuchzeria. Permanent pollen or spore dyads are extremely rare among extant land plants and in no case have they been studied developmentally. The paper provides new data on flower development and the first description of pollen development in Scheuchzeria. Flowers are arranged in a closed raceme. Development of lateral flowers is unidirectional, with delayed initiation of abaxial tepals and stamens. Flowers are often trimerous and pentacyclic, but numerous deviations from this groundplan are observed. Dyad development is investigated from microspore mother cells to mature pollen and their germination by electron microscopy and cytochemical methods. Meiosis is successive. Tetrads are irregular (42%), tetragonal (35%), decussate (13%), linear (7%) and T‐shaped (3%). During the tetrad period, the microspores are surrounded by a callose special wall of different thickness. Disintegration of tetrads into two dyads takes place along the plane of the first cytokinesis, where the thickness of the callose wall is maximal. Pollen grains are held together in the dyads due to a simple fusion of tectal layers, this fusion takes place at the late tetrad period. Developmental data did not reveal any possible aperture sites in Scheuchzeria. This favours the hypothesis of complete loss and subsequent regain of apertures in the course of evolution of the ‘tepaloid clade’ of Alismatales.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Diversity Of Tetrad Typesmentioning

confidence: 93%

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A developmental study of pollen dyads and notes on floral development inScheuchzeria(Alismatales: Scheuchzeriaceae)

et al. 2016

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Formation pattern in five types of pollen tetrad in Pseuduvaria trimera (Annonaceae)

2018

Protoplasma

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In basal angiosperms, there are several types of permanent tetrad but their formation pattern remains elusive. Pseuduvaria trimera has five types of tetrads and is the species with the most abundant tetrad types in Annonaceae. In order to interpret the formation pattern of different tetrad types, pollen development was investigated from the microspore mother cell stage to the bicellular pollen stage and the ultrastructure of pollen wall in the five tetrad types using light microscopy, transmission electron microscopy, and confocal laser scanning microscopy. Both successive and intermediate cytokinesis were observed within the same anther. The nucleus location of the microspores together with cytokinesis determine the number and the spatial arrangement of callose plates, and further have an effect on the tetrad types. The anthers with or without septation and the arrangement of microsporocytes might be also related to the tetrad type. The individual pollen grains within the tetrads are connected with each other by crosswall cohesion and cytoplasmic channels at localized points in the proximal walls. The various types of tetrads, cytokinesis, and cohesion in P. trimera reflect the high diversity in pollen development, which enhances the dramatic variety in pollen morphology in this family. Our observations of the development of tetrads provided some new insights for interpreting the factors influencing the types of tetrads, and reported the existence of a cytoplasmic channel in Annonaceae for the first time.

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О. П. Камелина. Систематическая Эмбриология Цветковых Растений. Двудольные. Барнаул: Изд-Во Артика, 2009. 501 С.; Систематическая Эмбриология Цветковых Растений. Однодольные. Барнаул: Печатная Компания Артика, 2011. 191 С, "Ботанический Журнал"

Шамров¹,

Titova²

2013

Ботанический журнал

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A brief outline of information published in a two-volume monograph by O. P. Kamelina «Systematic embryology of flowering plants» (2009, 2011) is given. The monograph covers both dicotyledonous and monocotyledonous plants. It presents the glossary of key terms in embryology, embryological characteristics of families with the list of studied species, the lists of references and conclusions on all analyzed orders.

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Premeiotic Microsporocyte Cell Shape Influences Shape of Tetrads during Microsporogenesis

Cited by 4 publications

References 41 publications

A developmental study of pollen dyads and notes on floral development inScheuchzeria(Alismatales: Scheuchzeriaceae)

A developmental study of pollen dyads and notes on floral development inScheuchzeria(Alismatales: Scheuchzeriaceae)

Formation pattern in five types of pollen tetrad in Pseuduvaria trimera (Annonaceae)

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