Poster: Reproductive Development

Abs # 471: OsSPO11-1, a rice SPO11 homologue, is differentially expressed in reproductive and vegetative organs.

Presenter:	Wang, Tai , twang@ns.ibcas.ac.cn
Authors	Wang, Tai  (A)   Ding, Zhao Jun  (A)   Chong, Kang  (A)
Affiliations:	(A): Res. Ctr. for Mol. & Dev. Biol., Inst. of Botany, Chinese Academy of Sciences

Spo11 protein is an eukaryotic homologue of the catalytic subunit TopVIA of archaebacterial topoisomerase VI. Yeast Spo11 is a meiosis-specifc protein and has been shown to be directly involved in the formation of meiotic DNA double-strand breaks that initiate meiotic recombination. Here,SPO11 homologue of rice, termed OsSPO11-1. The gene is a single-copy gene in rice genome, consists of 3 exons and 2 introns, and is localized in chromosome 11. OsSPO11-1 produces 4 transcript variants with differences in intron composition at 5' UTR by differential splicing of intron 1 and intron 2 with novel non-canonical splice sites CA-TT and GG-TA, respectively, which encodes 2 isoforms. The smaller isoform, encoded by the unspliced (OsSPO11-1A)and the intron 2-containing (OsSPO11-1B) transcripts, consists of 246 amino acids and is identical to C-terminal 246 amino acids of the larger one, which is encoded by the intron 1-containing (OsSPO11-1C) and the fully spliced (OsSPO11-1D) transcripts, and deleted N-terminal first 56 amino acids present in the larger one. OsSPO11-1A/C are accumulated preferentially in flowers, OsSPO11-1B is flower-specific; on the contrary, OsSPO11-1D is accumulated dominantly in vegetable organs. In situ hybridization of flower slices indicates that the transcripts can be detected not only in meiotic male and female generative cells, but also in tapetal cells of anthers and vascular bundle cells of different floral organs,in accordance with the predicted function of Spo11 in the initiation of meiotic recombination. Providing hints that Spo11 proteins might function in somatic development but involved in meiotic recombination.