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Cytoskeletal mechanisms in positioning of the second‐division spindles and meiotic restitution in tobacco ( Nicotiana tabacum L.) microsporogenesis
Author(s) -
Sidorchuk Yuriy Vladimirovich,
Deineko Elena Victorovna
Publication year - 2017
Publication title -
cell biology international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 77
eISSN - 1095-8355
pISSN - 1065-6995
DOI - 10.1002/cbin.10772
Subject(s) - meiosis , prometaphase , biology , microtubule , prophase , microbiology and biotechnology , telophase , nicotiana tabacum , phragmoplast , cytoskeleton , tubulin , ploidy , spindle pole body , cell division , botany , spindle apparatus , genetics , cell , gene
Microsporogenesis patterns of the polyploid (2 n = 4 x = 96) and diploid (2 n = 2 x = 48) Nicotiana tabacum L. (cv. Havana Petit line SR1) plants have been analyzed and compared. Four types of abnormal positions of the second‐division spindles—tripolar, parallel, proximal, and fused—have been observed. Of these abnormalities, only tripolar (2.4%) and parallel (1.4%) spindles are observable in diploid plants. As for polyploids, the increased ploidy is accompanied by an increase in the incidence of tripolar (22.8%) and parallel (8.1%) spindle orientations and emergence of two remaining abnormalities (proximal and fused spindles, 3.3%). As has been shown, the spindle position abnormalities in diploid plants have no effect on the meiotic products, whereas both dyads and triads are detectable among the tetrads in polyploid plants. Analysis of cytoskeletal remodeling has allowed for the insight into the role of interzonal radial microtubule system in spindle positioning during the second division. The reason underlying the change in spindle positioning is disturbed polymerization–depolymerization processes and interdigitation of microtubule plus ends within the interzonal cytoskeleton system in late telophase I–interkinesis and prophase II. As has been demonstrated, fused second‐division spindles are formed as a result of fused cytoskeletal structures in prophase–prometaphase II in the case when the nuclei are drawn abnormally close to one another.