Early stages of anther development in flowering plants

Abstract

The analysis showed that when studying the anther of flowering plants there is a comp lex of unsolved embryological problems. First of all, they relate to the first stages of microsporangium initiation and time of archesporium differentiation. Many of classifications of microsporangium wall formation were worked out on the base of parietal tissue formation features. Of the 4 types of microsporangium wall formation proposed by Davis (1966), 2 types (basic and reduced) are contro ver sial. In the classification by Teryokhin et al. (1993, 2002), the basic type was in cluded as a complicated variation in the centripetal type, and the reduced type as a reduced variation in the centrifugal type. In our opinion, in angiosperms only two types of formation of microsporangium wall layers can be distinguished: centrifu gal and centripetal. As our study has shown, the reduced type, as well as, the basic one, are variations of the centripetal type, while the reduced type is a modification of the typical variation. Various points of view on the formation of microsporan gium layers are discussed not only from the outside of the parietal cells, but also from the lateral and internal sides. K e y w o r d s : anther, microsporangium wall formation, development, flowering plants Р Е З Ю М Е Шамров И.И., Анисимова Г.М., Бабро А.А. Ранние стадии развития пыльника у цветковых растений. Проведенный анализ показал, что при изучении строения и развития пыльника цветковых растений существует комплекс нерешенных эмбриологических проблем. Они касаются, прежде всего, начальных стадий заложения микроспорангия и времени дифферен циации археспория. Большинство классификаций по формированию стен ки микроспорангия разработаны на основе признаков париетальной ткани. Из 4 типов образования стенки микроспорангия, выделенных Davis (1966), 2 типа (основной и редуцированный) являются спорными. В классифика ции, предложенной Терехиным и др. (1993, 2002), основной тип включен как компликатная вариация в центростремительный тип, а редуцированный тип рассматривается в качестве редуцированной вариации центробежного типа. По нашему мнению, у цветковых растений можно выделить только 2 типа: центробежный и центростремительный. Как показало наше исследо вание, редуцированный тип, как и основной, являются вариациями центро стремительного типа, при этом редуцированный тип представляет собой модификацию типовой вариации. Обсуждаются различные точки зрения о формировании слоев микроспорангия не только с наружной стороны из клеток париетального слоя, но и с латеральных и внутренней сторон.

Seed productivity of Rosa oxyodon Boiss

“…The high level of variability of the trait allows the assumption that the trait is under strong selection pressure. The number of carpels and ovules, on the other hand, is strictly determined by genotype [20,21]. A number of researchers [22,23] found that one of the reasons of lower seed productivity is abnormalities in embryonic development.…”

Micromorfología y ultraestructura de las anteras y los granos de polen en diez genotipos élite de Theobroma cacao (Malvaceae)

“…Las principales características analizadas en los granos de polen se resumen en la Tabla 2. DISCUSIÓN La pared de las anteras maduras de T. cacao presenta una epidermis persistente, un endotecio con engrosamientos fibrilares que se encuentra recubierto por restos de las paredes tapetales, este patrón histológico básico, es común en las anteras maduras y dehiscentes de la mayoría de las angiospermas (Passarelli & Cocucci, 2006;Wilson, Song, Taylor, & Yang, 2011;Wei, Xu, & Li, 2015;Shamrov, Anisimova, & Babro, 2020), incluido Malvaceae (Tang, Gao, Wang, & Chen, 2006;Galati, Monacci, Gotelli, & Rosenfeldt, 2007;Tang, Gao, & Xie, 2009;Lattar, Galati, & Ferruci, 2014). Concordando con las observaciones de Manning (1996), los engrosamientos fibrilares presentes en el endotecio de los genotipos de T. cacao son el tipo anular y es similar a lo registrado para varias especies dentro de la familia Malvaceae (Lattar et al, 2014); aunque no son exclusivos de este grupo de plantas (French, 1985;Manning & Linder, 1990;Manning, 1996;Tebbitt & Maciver, 1999;Carrizo, 2002;Nakamura, Longhi-Wagner, & Scatena, 2010;Gotelli, Galati, & Zarlavsky, 2016).…”

Tapetum Types and Forms in Angiosperms

“…As our studies have shown, the reduced as well as the basic types are variations of the centripetal type: the basic type is included in a complicated variation, while the reduced type is a modification of the typical variation (Shamrov et al, 2020). In some flowering plants (Allium caspium (Pall.)…”

“…An analysis of the available data indicates that in plants with the basic and dicotyledonous types of microsporangium wall formation (according to Davis, 1966), fibrous thickenings are formed not only in the subepidermal, but also in the remaining underlying layers. Consequently, the formation of multi-layered endothecium is characteristic of complicated variations of both centrifugal and centripetal types, proposed by Shamrov et al (2020). Plants with flowers developing in water in the case of hyphydrogamy (Ceratophyllaceae, Cymodoceae, Najadaceae, Hydrocharitaceae) and species with cleistogamous flowers lack fibrous thickenings in the microsporangium wall (Fig.…”

“…At present, there is a complex of unresolved problems in the study of anthers of flowering plants. They concern the initial stages of microsporangium development, the ways of layer formation in microsporangium wall and characteristics of layers in the course of development (Shamrov et al, 2020). The paramount purpose of that study was to identify the diversity of the tapetum, the features of its formation and structure.…”