Heterologous Complementation of SPO11-1 and -2 Depends on the Splicing Pattern

Area of Science:

• Plant biology
• Molecular genetics
• Cell biology

Background:

• Meiosis, essential for sexual reproduction, involves programmed DNA double-strand breaks (DSBs).
• Plants possess two distinct SPO11 paralogs (SPO11-1 and SPO11-2), both crucial for DSB induction in meiotic prophase I.
• Mammals and fungi utilize a single SPO11 protein, contrasting with the plant system.

Purpose of the Study:

• To investigate the specific functions and evolutionary divergence of the two meiotic SPO11 paralogs in land plants.
• To elucidate the spatiotemporal localization and functional specificity of SPO11-1 and SPO11-2.
• To understand the sequence-based requirements and species-specific adaptations of these paralogs.

Main Methods:

• Immunostaining to determine the spatiotemporal localization of SPO11-1 and SPO11-2 during meiosis.
• Functional analysis through reciprocal exchange of SPO11-1 and SPO11-2 in *Arabidopsis*.
• Site-directed mutagenesis by exchanging regions between SPO11-1 and SPO11-2 to identify sequence-specific functions.
• Refinement of aberrant splicing patterns and their developmental timing.

Main Results:

• Distinct spatiotemporal localization patterns were observed for SPO11-1 and SPO11-2.
• Functional analysis revealed species-specific roles for SPO11-1 and SPO11-2.
• Region-specific exchanges identified sequence-dependent functions for both SPO11 paralogs.
• Aberrant splicing was precisely linked to specific developmental phases.

Conclusions:

• The functions of plant meiotic SPO11 paralogs are highly sequence-specific.
• Orthologs of these SPO11 proteins exhibit species-specific adaptations and functions.
• The dual SPO11 system in plants represents a unique evolutionary trajectory for regulating meiotic recombination.