Selective inhibition of the growth of incompatible pollen tubes by S-protein in the Japanese pear |
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Authors: | S. Hiratsuka Shao-Ling Zhang E. Nakagawa Yoshitaka Kawai |
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Affiliation: | (1) Faculty of Bioresources, Mie University, Tsu, Mie 514-8507, Japan e-mail: hiratuka@bio.mie-u.ac.jp Fax: +81-59-231-9637, JP;(2) Department of Horticulture, Nanjing Agricultural University, Nanjing 210095, China, CN |
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Abstract: | The S-allele-associated proteins (S-proteins) in the styles of the Japanese pear (Pyrus serotina Rehd. var. culta Rehd.) were purified by cation exchange chromatography. Their inhibitory action on the growth of incompatible pollen tubes (pollen tubes bearing the same S- allele as in the style from which the S-proteins were prepared) was characterized in vitro. Germination and tube growth of self-pollen (pollen from the same cultivar from which the S-proteins were prepared) decreased dose-dependently when the S-protein was added to the medium. Tube length was reduced to 10% that of compatible pollen tubes (pollen tubes bearing the S-allele different from that in the style from which the S-proteins were prepared) at 1.5 μg μl1. S-proteins from Shinsui (S 4 S 5 ) also inhibited growth of cross-incompatible Kosui (S 4 S 5 ) pollen tubes, but not of compatible Chojuro (S 2 S 3 ) pollen tubes. After inactivation of RNase of the S- protein, the inhibitory action of the S-protein disappeared. These results indicate that the S-protein acts directly to inhibit growth of incompatible pollen tubes in Japanese pear styles, and that the RNase activity of the protein is essential for the biological function. However, small amounts of proteins that co-migrated with the S-protein may also play some roles in the inhibition. This is the first report on the selective inhibitory action of S-proteins in Rosaceae. Received: 11 April 2000 / Revision accepted: 28 September 2000 |
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Keywords: | Japanese pear Pollen inhibition Pyrus serotina RNase S-protein |
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