Apple MdABCF assists in the transportation of S‐RNase into pollen tubes

Summary Self‐incompatibility ( SI ) is a reproductive isolation mechanism in flowering plants. Plants in the S olanaceae, R osaceae and P lantaginaceae belong to the gametophytic self‐incompatibility type. S ‐ RN ase, which is encoded by a female‐specific gene located at the S locus, degrades RNA in the pollen tube and causes SI . Recent studies have provided evidence that S ‐ RN ase is transported non‐selectively into the pollen tube, but have not specified how this transportation is accomplished. We show here that the apple ( M alus domestica ) MdABCF protein, which belongs to group F of the ABC transporter family, assists in transportation of S ‐ RN ase into the pollen tube. MdABCF is located in the pollen tube membrane and interacts with S ‐ RN ase. S ‐ RN ase was unable to enter the pollen tube when MdABCF was silenced by antisense oligonucleotide transfection. Our results show that MdABCF assists in transportation of either self or non‐self S‐ RN ase into the pollen tube. Moreover, MdABCF coordinates with the cytoskeleton to transport S ‐ RN ase. Blockage of S ‐ RN ase transport disrupts self‐incompatibility in this system.