The synaptonemal complex (SC), a meiosis-specific zipper-like tripartite structure, is constituted by the two parallel lateral elements (LEs) and the central elements (CEs). It is highly conserved among various eukaryotes. During meiotic prophase I, SC is considered as the structural framework in which homologous recombination occurs and genetic information rearrangement accomplishes. The identification of new SC components, companied with the precise understanding of SC would, therefore, be critically important for normal haploid gametes and accurate life cycle of sexual reproduction organisms.

A research team led by Prof. CHENG Zhukuan from the Institute of Genetics and Developmental Biology of Chinese Academy of Sciences, found that P31^comet is a new SC member in rice meiosis. P31^comet was characterized to participate in metaphase/anaphase transition during mitosis. This work, for the first time, provides experimental evidence for P31^comet function in meiosis. The study has been published in PNAS.

In this study, researchers found that P31^comet colocalizes with ZEP1 (a transverse filament protein of rice SC) to the central region between two axial elements (AEs) in an interpedently pattern and P31^comet interacts with CENTRAL REGION COMPONENT 1 (CRC1, a SC component in rice) in yeast two-hybrid assays. These results suggest possible involvement of P31^comet in SC installation through its cooperation with CRC1.

Their further investigation revealed that P31^comet is also essential for the programmed double-strand break initiation during rice meiosis. The abnormal chromosome fragmentation in Oscom1 and Osrad51c meiocytes is suppressed in both Oscom1 p31^comet and Osrad51c p31^comet, showing that P31^comet is a prerequisite for the double-strand break (DSB) repair.

This work is supported by the National Key Research and Development Program and National Natural Science Foundation of China.

Figure: P31^comet colocalizes with ZEP1 between two axial elements (A, B) and P31 ^comet interacts with CRC1 in Y2H assay (C). (Image by CHENG Zhukuan)