Cytomixis in plants: facts and doubts

Mursalimov, Sergey; Дейнеко, Е. В.

doi:10.1007/s00709-017-1188-7

Cited by 27 publications

(25 citation statements)

References 93 publications

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“…4F). This observation resembles cytomixis, a so far unexplained phenomenon which occurs during microsporogenesis in several higher plants (for review see 20 ). These findings, in particular the large variation of guard cell and genome size in Le .…”

Section: Resultsmentioning

confidence: 56%

Variation in genome size, cell and nucleus volume, chromosome number and rDNA loci among duckweeds

Hoang

Schubert

Meister

et al. 2019

Sci Rep

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Duckweeds are small, free-floating, largely asexual and highly neotenous organisms. They display the most rapid growth among flowering plants and are of growing interest in aquaculture and genome biology. Genomic and chromosomal data are still rare. Applying flow-cytometric genome size measurement, microscopic determination of frond, cell and nucleus morphology, as well as fluorescence in situ hybridization (FISH) for localization of ribosomal DNA (rDNA), we compared eleven species, representative for the five duckweed genera to search for potential correlations between genome size, cell and nuclei volume, simplified body architecture (neoteny), chromosome numbers and rDNA loci. We found a ~14-fold genome size variation (from 160 to 2203 Mbp), considerable differences in frond size and shape, highly variable guard cell and nucleus size, chromosome number (from 2n = 36 to 82) and number of 5S and 45S rDNA loci. In general, genome size is positively correlated with guard cell and nucleus volume (p < 0.001) and with the neoteny level and inversely with the frond size. In individual cases these correlations could be blurred for instance by particular body and cell structures which seem to be linked to specific floating styles. Chromosome number and rDNA loci variation between the tested species was independent of the genome size. We could not confirm previously reported intraspecific variation of chromosome numbers between individual clones of the genera Spirodela and Landoltia .

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Section: Resultsmentioning

confidence: 56%

Variation in genome size, cell and nucleus volume, chromosome number and rDNA loci among duckweeds

Hoang

Schubert

Meister

et al. 2019

Sci Rep

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“…Natural allopolyploids are stable and well adapted, whereas synthetic allopolyploids can exhibit incompatible interactions between parental genomes, i.e., intergenomic incompatibilities ( Comai, 2000 ). Cytomixis, as was observed here in both allopentaploids and allohexaploids ( Figure 1 ), can be the consequence of such intergenomic incompatibilities, but in Hylocereus species—like in other species—the biological and evolutionary significance of cytomixis is not known ( Mursalimov and Deineko, 2018 ).…”

Section: Discussionmentioning

confidence: 72%

“…The pollen grains of H. undatus exhibited a uniform diameter of 70–80 μm, but those of H. megalanthus showed a wide variation in diameter, with values lying between 90 and 190 μm. These differences in diameter represent different ploidy levels in the viable pollen grains and are, most probably, due to meiotic abnormalities, such as the formation of unreduced gametes, unbalanced chromosome segregation, or cytomixis ( Ramanna and Jacobsen, 2003 ; Shamina, 2005 ; Mursalimov and Deineko, 2018 ). All the above findings indicate that both allopentaploids and allohexaploids can reproduce by sexual reproduction, since both produce a certain percent of viable male and female gametes.…”

Section: Discussionmentioning

confidence: 99%

In Support of Winge's Theory of “Hybridization Followed by Chromosome Doubling”

et al. 2020

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Polyploidy-or chromosome doubling-plays a significant role in plant speciation and evolution. Much of the existing evidence indicates that fusion of unreduced (or 2n) gametes is the major pathway responsible for polyploid formation. In the early 1900s, a theory was put forward that the mechanism of "hybridization followed by chromosome doubling" would enable the survival and development of the hybrid zygote by providing each chromosome with a homolog with which to pair. However, to date there is only scant empirical evidence supporting this theory. In our previous study, interspecific-interploid crosses between the tetraploid Hylocereus megalanthus, as the female parent, and the diploid H. undatus, as the male parent, yielded only allopentaploids, allohexaploids, and 5x-and 6x-aneuploids instead of the expected allotriploids. No viable hybrids were obtained from the reciprocal cross. Since H. undatus underwent normal meiosis with regular pairing in the pollen mother cells and only reduced pollen grains were observed, the allohexaploids obtained supported the concept of "chromosome doubling." In this work, we report ploidy level, fruit morphology, and pollen viability and diameter in a group of putative hybrids obtained from an embryo rescue procedure following controlled H. megalanthus × H. undatus crosses, with the aim to elucidate, for the first time, the timing and developmental stage of the chromosome doubling. As in our previous report, no triploids were obtained, but tetraploids, pentaploids, hexaploids, and 5x-and 6xaneuploids were found in the regenerated plants. The tetraploids exhibited the morphological features of the maternal parent and could not be considered true hybrids. Based on our previous studies, we can assume that the pentaploids were a result of a fertilization event between one unreduced (2n) female gamete from the tetraploid H. megalanthus and a normal (n) haploid male gamete from H. undatus. All the allohexaploids obtained from the embryo rescue technique where those that regenerated from fertilized ovules 10 days after pollination (at the pro-embryo stage), showing that the chromosome doubling event occurred at a very early development stage, i.e., at the zygote stage or shortly after zygote formation. These allohexaploids thus constitute empirical evidence of "hybridization followed by chromosome doubling."

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“…Due to slow-paced progression during prophase I, for instance, assembly/disassembly of the bouquet and the SC or formation and dissolution of interlocks could be studied in detail. In numerous plant species, primarily during male prophase I, cytomixis occurs, i.e., migration of whole nuclei, chromosomes and/or chromatin between plant cells through intercellular channels (cytomictic channels) resulting in the formation of unreduced, polyploid, aneuploid or sterile pollen ( Mursalimov et al, 2015 ; Mursalimov and Deineko, 2017 ). How cytomixis is regulated or interconnected to meiotic progression is unclear.…”

Section: Novel Approaches Exploiting Non-model Plantsmentioning

confidence: 99%

Tackling Plant Meiosis: From Model Research to Crop Improvement

Lambing

Heckmann

2018

Front. Plant Sci.

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Genetic engineering and traditional plant breeding, which harnesses the natural genetic variation that arises during meiosis, will have key roles to improve crop varieties and thus deliver Food Security in the future. Meiosis, a specialized cell division producing haploid gametes to maintain somatic diploidy following their fusion, assures genetic variation by regulated genetic exchange through homologous recombination. However, meiotic recombination events are restricted in their total number and their distribution along chromosomes limiting allelic variations in breeding programs. Thus, modifying the number and distribution of meiotic recombination events has great potential to improve and accelerate plant breeding. In recent years much progress has been made in understanding meiotic progression and recombination in plants. Many genes and factors involved in these processes have been identified primarily in Arabidopsis thaliana but also more recently in crops such as Brassica, rice, barley, maize, or wheat. These advances put researchers in the position to translate acquired knowledge to various crops likely improving and accelerating breeding programs. However, although fundamental aspects of meiotic progression and recombination are conserved between species, differences in genome size and organization (due to repetitive DNA content and ploidy level) exist, particularly among plants, that likely account for differences in meiotic progression and recombination patterns found between species. Thus, tools and approaches are needed to better understand differences and similarities in meiotic progression and recombination among plants, to study fundamental aspects of meiosis in a variety of plants including crops and non-model species, and to transfer knowledge into crop species. In this article, we provide an overview of tools and approaches available to study plant meiosis, highlight new techniques, give examples of areas of future research and review distinct aspects of meiosis in non-model species.

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Cytomixis in plants: facts and doubts

Cited by 27 publications

References 93 publications

Variation in genome size, cell and nucleus volume, chromosome number and rDNA loci among duckweeds

Variation in genome size, cell and nucleus volume, chromosome number and rDNA loci among duckweeds

In Support of Winge's Theory of “Hybridization Followed by Chromosome Doubling”

Tackling Plant Meiosis: From Model Research to Crop Improvement

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