Fallen-expressed S-RNases are not involved in self incompatibility in Lycopersicon peruvianum

Self-incompatibility in solanaceous plants is gametophytically controlled b y a multiallelic S-locus. The only known S-locus product is a series of ext racellular ribonucleases (the S-RNases) which are expressed in the mature s tyle and determine its self-incompatibility phenotype. Potentially, S-RNase s also determine the self-incompatibility phenotype of pollen as some solan aceous plants express this protein for a brief period during anther develop ment. To test this, we first showed that the S-3-RNase of Lycopersicon peru vianum is expressed during anther development. We then transformed L. peruv ianum plants with sense and antisense versions of the S-3-RNase coding regi on under the control of a pollen-specific promoter. Pollen from the transge nic plants accumulated S-3-RNase transcripts and the S-3-RNase protein was detected immunologically in the sense transgenic plants. However, neither t he sense nor the antisense S-3-RNase constructs altered the self-incompatib ility phenotype of pollen from the transgenic plants, demonstrating the S-3 -RNase is not the pollen product of the S-3-allele.