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In vitro pollen tube growth inhibition by partially purified S-RNase from styles of Prunus avium L.

Matsumoto, D., Machida, Y., Taira, S.
Acta horticulturae 2019 no.1231 pp. 99-104
Prunus avium, Solanaceae, cation exchange chromatography, cytotoxicity, fruit trees, gametophytes, growth retardation, in vitro studies, pistil, pollen, pollen tubes, ribonucleases
Prunus fruit tree species exhibit the S-RNase-based gametophytic self-incompatibility (GSI), which uses S-RNase as the pistil determinant. S-RNase is a T2/S-type ribonuclease protein secreted in the style transmitting tract. It is considered to be taken-up non-selectively by pollen tubes and to elicit cytotoxicity specifically in cognate pollen tubes, resulting in the inhibition of tube growth. In two other taxa that exhibit S-RNase-based GSI, the family Solanaceae and the Maleae tribe within the Rosaceae family, in vitro assays have been successfully developed to demonstrate the induction of SI using style extracts and isolated S-RNase. In order to develop an equivalent in vitro assay in Prunus, we tested the effect of S-RNase on in vitro cultured pollen in sweet cherry (Prunus avium L.). S-RNases were isolated from style extracts of 'Satonishiki' (S(3)S(6)) and 'Rainier' (S(1)S(4)) by cation exchange chromatography. Neither isolated S-RNase affected pollen germination, but both of them inhibited the pollen tube growth in a self-specific manner. These results indicated the feasibility of developing an in vitro SI assay in Prunus.