A tripartite pollen killer-protector system confers temperature-sensitive inter-subspecific reproductive isolation in...

Area of Science:

• Genetics
• Molecular Biology
• Evolutionary Biology

Background:

• Hybrid sterility is crucial for speciation, but its molecular basis and environmental influence are poorly understood.
• Understanding reproductive isolation mechanisms in crops like rice is vital for agriculture and evolution studies.

Purpose of the Study:

• To elucidate the molecular mechanisms of temperature-sensitive hybrid sterility in indica-japonica rice.
• To investigate the role of the Sa locus in rice reproductive isolation and adaptation.

Main Methods:

• Genetic analysis to identify key genes at the Sa locus.
• Protein interaction, ubiquitination, and degradation assays to study molecular mechanisms.
• Comparative genomics and haplotype analysis to trace evolutionary history.

Main Results:

• Identified a three-gene Sa locus with temperature-sensitive alleles (SaFL+, SaFL-) controlling pollen viability.
• Discovered that SaF+ and SaM+ form a pollen-killer complex targeting COX11, causing male sterility.
• Showed SaFL- rescues fertility at high temperatures, while SaFL+ prevents killer complex formation.

Conclusions:

• The Sa locus acts as a temperature-sensitive reproductive isolation system in rice.
• This system likely played a role in rice domestication, latitudinal adaptation, and speciation.
• Environmental adaptation and reproductive isolation are intertwined in rice evolution.