A Multiprotein Complex Regulates Interference-Sensitive Crossover Formation in Rice

Area of Science:

• Genetics
• Molecular Biology
• Plant Science

Background:

• Meiotic crossovers (COs) are essential for proper chromosome segregation in eukaryotes.
• ZMM proteins, including ZIP2 and SPO16, are conserved and critical for CO formation in yeast.
• The conservation of these mechanisms in plants, specifically rice, remained unclear.

Purpose of the Study:

• To investigate the functions of rice ZIP2 ortholog (OsSHOC1) and SPO16 ortholog (OsPTD) in meiotic CO formation.
• To elucidate the interactions between OsSHOC1, OsPTD, and other ZMM proteins in rice.
• To determine the conserved roles of these proteins in plant meiosis.

Main Methods:

• Characterization of OsSHOC1 and OsPTD gene functions through disruption.
• Analysis of meiotic recombination intermediates and CO numbers.
• Protein-protein interaction studies using bimolecular fluorescence complementation and yeast-three hybrid assays.
• Genetic analysis to determine epistatic relationships.

Main Results:

• Disruption of OsSHOC1 reduced CO numbers by approximately 17% without affecting synapsis or early recombination.
• OsSHOC1 interacts with OsPTD, OsZIP4, and OsMSH5, while OsPTD interacts with OsHEI10.
• OsSHOC1 and OsPTD are required for the loading of other ZMM proteins, and their localization is dependent on OsZIP4 and OsHEI10.
• OsSHOC1 and OsPTD were found to be epistatic to OsHEI10 and OsZIP4 in CO formation.

Conclusions:

• OsSHOC1 and OsPTD play essential, conserved roles in promoting class I meiotic CO formation in rice.
• These proteins form multiple protein complexes with other ZMM proteins (OsZIP4, OsHEI10) to regulate CO formation.
• The findings reveal a conserved mechanism for CO control in plants, involving protein complex formation and epistatic interactions.