Molecular mechanism of the recognition of the style to pollen with discriminate S-genotype in gametophytic self-incompatibility of apple

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To elucidate a molecular mechanism of gametophytic self-incompatibility of apple the interactive proteins to the S-RNase were screened from the pollen with distinctive S-genotype. The used varieties of apples is Stalking-Delicious (SD)(S-genotype : Sc, Se), Golden-Delicious (GD)(Sa, Sb).○Se-and Sc-RNase as S-RNase from SD were purified by our previously described method.○From germinated pollen of the varieties, SD and GD, crude extracts of soluble proteins and total RNA fractions were prepared.○The specific activities of the purified RNases were compared with other RNases (RNase A and T2) by using various RNA as substrate. The S-RNases showed very low values in specific activity than that of RNase A.○An affinity column of which Se-RNase bound to Hi-Trap (Pharmacia) was prepared. The crude pollen extracts were treated with the column and two absorbed proteins showed molecular mass of 48 and 66 KD on SDS-PAGE were obtained These proteins were confirmed to be a substance which interacts s … More pecifically with Se S-RNase by the immunodetection using Se-RNase antibody. Both substances, however, did not change the activity of the S-RNase to the tube elongation of pollen with the same S-genotype or alternative one.○The proteins, 48 and 66 KD of Mr, were also obtained by immune precipitation method.○The interaction of Se-RNase with soluble pollen proteins was examined by surface plasm on resonance method using Biacore 2000 (Biacore) with a Se-RNase binding sensor tip. For all fractions separated by DE chromatography of pollen crude extracts the protein interactions were measured. Only two fractions containing 48 or 66 KD of Mr were showed large Ka values and slow depression of Kd.In this studies the presence of interactive proteins to S-RNase from pollen extracts were confirmed by affinity column, immune precipitation, and surface plasmon resonance methods. These substances, however, did not inhibit the RNase activity of S-RNase in vitro an assay system, and therefore, additional substances derived from pollen may need to recognize the difference between self and cross pollen. Less