Rapid meiotic prophase chromosome movements inArabidopsis thalianaare linked to essential reorganization at the nuclear envelope

Abstract

Meiotic rapid prophase chromosome movements (RPMs) require connections between the chromosomes and the cytoskeleton, involving SUN (Sad1/UNC-84)-domain-containing proteins at the inner nuclear envelope (NE). RPMs remain significantly understudied in plants, notably with respect to their importance in the regulation of meiosis. Here, we demonstrate thatArabidopsis thalianameiotic centromeres undergo rapid (up to 500 nm/s) and uncoordinated movements during the zygotene and pachytene stages. RPMs are not affected by altered chromosome organization and recombination but are abolished in the double mutantsun1 sun2. We also document the changes in chromosome dynamics and nucleus organization during the transition from leptotene to zygotene, including telomere attachment to SUN-enriched NE domains, bouquet formation, and nucleolus displacement, all of which were defective insun1 sun2. These results establishA. thalianaas a new model species for studying the functional implications of meiotic RPMs and demonstrate the mechanistic conservation of telomere-led RPMs in plants.

Rapid Homolog Juxtaposition During Meiotic Chromosome Pairing

“…Another central feature of meiosis that contributes to all of these effects is cytoskeletonmediated end-led motion [8][9][10][11][12][13][14] . Chromosome telomeres are specifically linked to, and then through, the nuclear envelope via "LINC" complexes which, in turn, are associated with motor proteins that move along cytoskeletal actin or tubulin filaments.…”