Unveiling the Mysteries of Self-Incompatibility in Petunias

Ever wondered why some plants avoid self-pollination? Meet self-incompatibility (SI), a clever genetic trick that promotes cross-pollination. SI is like a bouncer at a plant party, letting in pollen from other plants but keeping its own pollen out. This happens thanks to a special gene called the S-locus, which has many different versions called S-alleles. Identifying these alleles has been tough due to their extreme variety.Scientists from a recent study used a fancy tool called the Oxford Nanopore MinION to explore the allelic diversity of the S-locus in Petunias. Petunias have a unique SI system where a secreted protein called S-RNase stops self-pollen tubes from growing. The team created a method to find S-alleles by searching for S-RNase sequences. They discovered 62 types, with 45 being new to science! To make sure their method was accurate, they double-checked with Sanger sequencing and crossing experiments. With their new data, they looked at the diversity, frequency, and shared polymorphism of S-alleles across different Petunia populations and species. This study is a big step forward in understanding how SI systems evolve in nature.