Ectopic Expression of a Self-Incompatibility Module Triggers Growth Arrest and Cell Death in Vegetative Cells

Area of Science:

• Plant reproductive biology
• Molecular genetics
• Plant signaling pathways

Background:

• Self-incompatibility (SI) is a crucial mechanism in many flowering plants, preventing inbreeding by rejecting self-pollen.
• In field poppy (Papaver rhoeas), SI is mediated by a female S-determinant (PrsS) and a male S-determinant (PrpS), both cysteine-rich peptides.
• Previous work established the intergeneric transfer of these S-determinants to Arabidopsis.

Purpose of the Study:

• To investigate the function of the Papaver rhoeas SI determinants (PrpS and PrsS) when ectopically expressed in Arabidopsis.
• To determine if the PrpS-PrsS module can induce self-recognition and self-destruction responses in a non-reproductive context.

Main Methods:

• Ectopic expression of PrpS and PrsS in Arabidopsis thaliana.
• Application of recombinant PrsS to seedling roots expressing PrpS.
• Inducible expression of PrsS in seedlings expressing PrpS.

Main Results:

• Ectopic expression of the PrpS-PrsS module in Arabidopsis induced a self-recognition:self-destruct response in vegetative cells.
• Recombinant PrsS application to PrpS-expressing roots caused S-specific growth inhibition and programmed cell death (PCD).
• Inducible PrsS expression in PrpS-expressing seedlings led to rapid, complete seedling death.

Conclusions:

• The bipartite PrpS-PrsS module from Papaver rhoeas can trigger growth arrest and PCD in vegetative plant cells, independent of its reproductive role.
• This study demonstrates the first heterologous, ectopic expression of a plant bipartite signaling module to induce such responses.
• Findings suggest that cysteine-rich peptides have diversified functions, including the regulation of growth and PCD in plants.