SELF-INCOMPATIBILITY IN JAPANESE PEARS: PECULIAR INHIBITORY ACTION OF S-RNASE ON SELF POLLEN-TUBE GROWTH IN VITRO

In Japanese pears (Pyrus pyrifolia Nakai), purified S-RNase (RNase associated with the self-incompatibility allele) from the styles can cause selective inhibition on the growth of self pollen-tubes in vitro, and its RNase activity is essential for the inhibitory action.
However, stylar proteins of the pear (proteins removed from S-RNase by cation exchange chromatography), which possessed three times higher RNase activity than S-RNase, did not show any inhibitory action.
When the biological function of several RNases, S-RNase, RNase T1, RNase T2 and RNase A, was compared in vitro, S-RNase against the self pollen showed the strongest inhibition, followed by RNase T1, RNase T2 and RNase A. S-RNase action on cross pollen was the weakest.
These results suggest that S-RNase and/or the pollen-tube recognize their mate in vitro and degrade RNAs in the tube, resulting in the cessation of pollen-tube elongation.

XXVI International Horticultural Congress: Key Processes in the Growth and Cropping of Deciduous Fruit and Nut Trees

S. Hiratsuka, A. Hirano, Y. Kawai, S.-L. Zhang

Pyrus pyrifolia, S-allele, RNase T₁, RNase T₂, RNase A

https://doi.org/10.17660/ActaHortic.2004.636.42