A relic S-RNase is expressed in the styles of self-compatible Nicotiana sylvestris

Abstract

We surveyed ribonuclease activity in the styles of Nicotiana spp. and found little or no activity in self-compatible species and in a self-compatible accession of a self-incompatible species. All self-incompatible species had high levels of ribonuclease activity in their style. Interestingly, one self-compatible species, N. sylvestris, had a level of stylar ribonuclease activity comparable to that of some self-incompatible Nicotiana species. A ribonuclease with biochemical properties similar to those of the self-incompatibility (S-)RNases of N. alata was purified from N. sylvestris styles. The N-terminal sequence of this protein was used to confirm the identity of a cDNA corresponding to the..