PT  - JOURNAL ARTICLE
AU  - Arnaud Ronceret
AU  - Inna Golubovskaya
AU  - Jia-Chi Ku
AU  - Ding Hua Lee
AU  - Ljudmilla Timofejeva
AU  - Ana Karen Gomez Angoa
AU  - Yu-Hsin Kao
AU  - Karl Kremling
AU  - Rosalind Williams-Carrier
AU  - Robert Meeley
AU  - Alice Barkan
AU  - W Zacheus Cande
AU  - Chung-Ju Rachel Wang
TI  - The dynamic association of SPO11-1 with conformational changes of meiotic axial elements in maize
AID  - 10.1101/489278
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 489278
4099  - http://biorxiv.org/content/early/2018/12/06/489278.short
4100  - http://biorxiv.org/content/early/2018/12/06/489278.full
AB  - Double strand breaks (DSBs) are generated at the beginning of meiosis by the evolutionarily conserved SPO11 complex that targets preferentially open chromatin. However, how DSBs are formed with respect to chromosome axes in a timely controlled manner remain unclear. Here, we analyzed the maize spo11-1 mutant and show that it strongly impairs DSB and bivalent formations. Notably, cytological characterization in the spo11-1 mutant revealed abnormally twisted axial elements that persisted until pachytene. In contrast, examinations of precisely staged wild-type meiocytes uncovered a transient remodeling of axial elements, changing from a curly to linear morphology during leptotene to zygotene transition, which is coincident with DSB formation. Using a SPO11-1 antibody, approximately 300 foci were detected from leptotene to pachytene in wild-type meiocytes. Interestingly, when examining distances between SPO11-1 foci to chromosome axes by super-resolution microscopy, predominant loading of SPO11-1 onto axial elements occurs concordantly with alteration of axial elements during leptotene. Taken together, our results suggest a dynamic localization of SPO11-1 during early meiosis that is correlated with a remodeling of the axial element conformation.Author Summary Meiosis is an important step in sexual reproduction for producing haploid gametes. Recombination is the most crucial step during meiotic prophase I, which enables pairing of homologous chromosomes prior to their reductional division, and generates new combinations of genetic alleles for transmission to the next generation. Meiotic recombination is initiated by generation of many DNA double-stranded breaks (DSBs), and their repair leads to reciprocal exchanges between paternal and maternal chromosomes. The activity, timing and location of this DSB machinery must be controlled precisely, but a full picture is still obscure. By studying maize SPO11-1, a topoisomerase-related enzyme required for making DSBs, we uncovered dynamic localization of SPO11-1 that is correlated to a transient structural change of the axial elements of wild-type plant meiocytes by super-resolution microscopy. Interestingly, loss of SPO11-1 impairs this structural change, resulting in a prolonged spiral morphology. Our study suggests an intimate relationship between SPO11-1 and axial elements and has implications for our understanding of how DSB formation is controlled in plants.