Fig 5 - uploaded by Elena V. Bazhina
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Meiosis anomalies in Picea obovata: (a) two chromosome groups in M I, (b) chromosomes beyond equatorial plates in M II, (c) chaotic divergence in A I, (d) chaotic divergence in one of the poles in A II, (e) bridge in A II, (f) agglutination in M II, (g) chromosomes beyond the plate in M I, (h) triad, (i) telophase I with broken bridge. Magnification: ob. 100×, oc. 10×.
Source publication
The results of meiosis studies during microsporogenesis in Siberian spruce (Picea obovata Ledeb.) in the forest ecosystems of the south of Central Siberia are presented. Meiosis features and different types of irregularities were detected. The features of male organ development show a high level of the Siberian spruce’s adaptation to the extreme cl...
Context in source publication
Context 1
... of chromosomes at the stage of ana-telophase I, chaotic arrangement of chromosomes at the stages of metaphase II and ana-telophase II, lagging of chromosomes at the stage of ana-telophase II, formation of three poles in ana-telophase II, formation of triads at the stage of the dyad as well as the dyad, triad, and pentad at the stage of tetrads (Fig. 5). In addition, the studied trees were found to have multiple disturbances of the second division of meiosis (Fig. ...
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Одним из важнейших факторов при изучении процесса фотосинтеза является состояние пигментного фонда фотосинтетического аппарата. При разных климатических и природных условиях фотосинтетическая активность будет стремиться к максимальным значениям. В условиях Юга Восточной Сибири наибольшее распространение имеют хвойные древостои, устойчивость и биоло...
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... The development and viability of plant pollen is determined by both internal (the state of the tree and metabolic features) and external (growth conditions, temperature, and precipitation) factors. Picea species are well adapted to the temperate climate of the boreal zone; Siberian spruce in the conditions of Central Siberia is characterized by regular development and a high viability of pollen (Bazhina et al., 2019(Bazhina et al., , 2020. However, technogenic stress can change the tree's resistance, while the strength and nature of the impact is determined by the properties of the tree and depends on its initial state. ...
The pollen viability of Siberian spruce (Picea obovata Ledeb.) has been studied on the border of the city Krasnoyarsk, as well as under unpolluted growth conditions. This study has discovered the variability and correlation between the functional characteristics of pollens, as well as a low rate of development anomalies. The viability of pollen growth in forest ecosystems of the middle mountains of the Eastern Sayans (the northeastern border of the Krasnoyarskie Stolby national park) have decreased under pollution press. The great variety of pollen viability characteristics of the Siberian spruce pollen makes the high degree of flexibility and adaptability of species reproductive processes evident.
... We caution against extrapolating polyploidization, hybrid proliferation, and assumed polyploid advantage under stress as an explanatory mechanism behind saccate pollen malformation spikes during extinction events (e.g., Neale et al. 2021) on the basis of two observations of extant lineages and one from the fossil record: (1) unreduced, malformed pollen grains have been found to be either completely sterile or require specialized conditions to germinate in vitro relative to normal haploid grains (Chira 1967), and their presence is associated with a large fraction of defective grains in pollen yields (Bazhina et al. 2007a(Bazhina et al. , 2019; (2) saccate pollen malformations associate with population-wide sterilization of ovules in UV-B-irradiated conifers (Benca et al. 2018); and (3) saccate pollen malformation spikes occur amid and/or during deforestation events in the end-Permian crisis (Hochuli et al. 2017;Mishra et al. 2018). If anything, malformed saccate pollen grains appear to signal reduced reproductive fitness, that is, lowered capacity of individuals to pass their genes on to subsequent generations, rather than signals of polyploid adaptive advantage, hybrid swarms, or range expansions. ...
... Similar observations were made in a subsequent, detailed cytological study of pollen sampled from microstrobili damaged by rust canker (Melampsorella cerastii [Persoon] Schröter) of drought-stressed Abies sibirica experiencing air pollution (Bazhina et al. 2007a (Bazhina et al. 2007a(Bazhina et al. , 2019. ...
... Such processes can result in and/or coincide with various forms of chromosome stickiness (agglutination) as well as abnormal chromosomal arrangements and segregations that result in daughter cells receiving unequal chromosomal complements ( Supplementary Fig. 2). Agglutination of chromosomes ( Supplementary Fig. 2:6) may be induced by mutations that lead to blockage of prophase I (Golubovskaya and Sitnikova 1980;Golubovskaya 1985;Bazhina et al. 2019). Loss of genetic material in daughter cells from chromosome fragments, chromosome emissions, and/or lagging chromosomes ( Supplementary Fig. 2:4,9,26) results in the formation of gametes with aneuploid (abnormal) numbers of chromosomes and a high fraction of defective pollen grains in conifers such as P. obovata (Bazhina et al. 2019). ...
Pollen malformations have been proposed as a paleoenvironmental stress proxy. However, the frequency and variability of pollen malformations under near-optimal conditions and environmental stress, as well as their developmental origins, remain unclear. To bridge these gaps, we compared pollen malformation frequencies and assemblages of 14 extant conifer genera of Pinaceae and Podocarpaceae producing saccate (winged) grains grown under near-optimal conditions. These baseline pollen yields were compared with those produced by Pinus mugo 'Columnaris' cultured under an abiotic stress-three experimentally heightened ultraviolet-B radiation (UV-B) regimes proposed for the end-Permian crisis. We additionally reviewed previous cytological literature of abnormal microsporogenesis in conifers. Under near-optimal conditions, malformations comprise <3% of pollen yields in 12 out of 13 bisaccate gen-era and >10% of yields in the naturally trisaccate Dacrycarpus dacrydioides. We detected no phylogenetic pattern in malformation assemblages of the baseline comparisons. UV-B-irradiated P. mugo produced significantly higher malformation frequencies and different assemblage compositions when compared with baseline bisaccate lineages. We propose that pollen malformations originate during the meiotic and tetrad stages of microsporogenesis and present a framework for the ontogeny of different malformation types seen in the fossil record. Malformations comprising >3% of bisaccate pollen yields can be used as a paleo-environmental stress proxy, but rare, naturally trisaccate lineages are not suitable for such assessments. Furthermore, heightened UV-B not only increases pollen malformation production, but also alters the types of abnormalities trees produce. Different environmental stresses may therefore leave behind distinct fingerprints in the fossil record.
Представлены результаты исследований мейоза при микроспорогенезе у ели сибирской (Picea obo-vata Ledeb.) в условиях интродукции. Выявлены особенности мейоза-четко идентифицируются все стадии профазы первого деления. Наблюдается значительная асинхронность делений не только у разных деревьев, но и в пределах одного микроспорангия. Отмечены особенности ориентации ве-ретен деления и нарушения развития на разных стадиях. Спектр нарушений был меньше, чем у ели сибирской в естественных популяциях Сибири. Особенности развития мужских репродуктивных структур свидетельствуют о наличии высокого адаптивного потенциала ели сибирской в условиях изменяющейся среды. Ключевые слова: ель сибирская, развитие мужских генеративных органов, мейоз, нарушения мейоза
