Some plants display inverted meiotic phase31/10/14Environment
Austria: The process of meiosis – the two-step series of cell divisions that make sexual reproduction and genetic diversity possible – in specific plant species has been divided to reveal that these plants display an inversion of the standard meiotic phases.
The co-ordination of the two meiotic chromosomal divisions (the reductional followed by the equational division) gives meiosis its distinctive characteristics: a reduction in the number of chromosomes by half, accompanied by mixing of parental chromosomes and swapping of regions between homologous chromosomes (crossing over).
The new research has shown that some species have developed their own strategy to ensure genetic diversity in their offspring with a variation of the ‘standard procedure’.
PhD student Gabriela Cabral and group leader Peter Schlögelhofer, at the Max F Perutz Laboratories (MFPL) of the University of Vienna and the Medical University of Vienna, examined meiosis in Rhynchospora pubera and R. tenuis.
Together with their colleagues at the Federal University of Pernambuco in Brazil and the Leibniz Institute of Plant Genetics and Crop Plant Research in Germany, the researchers at MFPL have shown that, in the investigated plant species, the homologous non-sister chromatids are associated with thin chromatin threads prior to the second meiotic division. These connections seem to provide sufficient force to allow proper orientation and disjunction during the second division.
Schlögelhofer explained: “Holocentric chromosomes create unique problems during meiosis that organisms with monocentric chromosomes do not face: they have to find another way to distribute the chromosomes correctly. The plant species in our study have a special strategy on how to solve the problem: they show an inversion of the canonical meiotic sequence, with the equational division preceding the reductional.”
The research has been published in the journal Nature Communications.