†Present address: WiCell Research Institute, PO Box 7365, Madison, WI 53707, USA.
The stylar 120 kDa glycoprotein is required for S-specific pollen rejection in Nicotiana
Article first published online: 8 AUG 2005
The Plant Journal
Volume 43, Issue 5, pages 716–723, September 2005
How to Cite
Nathan Hancock, C., Kent, L. and McClure, B. A. (2005), The stylar 120 kDa glycoprotein is required for S-specific pollen rejection in Nicotiana. The Plant Journal, 43: 716–723. doi: 10.1111/j.1365-313X.2005.02490.x
- Issue published online: 8 AUG 2005
- Article first published online: 8 AUG 2005
- Received 18 March 2005; revised 29 May 2005; accepted 7 June 2005.
- 120 kDa glycoprotein;
S-RNase participates in at least three mechanisms of pollen rejection. It functions in S-specific pollen rejection (self-incompatibility) and in at least two distinct interspecific mechanisms of pollen rejection in Nicotiana. S-specific pollen rejection and rejection of pollen from Nicotiana plumbaginifolia also require additional stylar proteins. Transmitting-tract-specific (TTS) protein, 120 kDa glycoprotein (120K) and pistil extensin-like protein III (PELP III) are stylar glycoproteins that bind S-RNase in vitro and are also known to interact with pollen. Here we tested whether these glycoproteins have a direct role in pollen rejection. 120K shows the most polymorphism in size between Nicotiana species. Larger 120K-like proteins are often correlated with S-specific pollen rejection. Sequencing results suggest that the polymorphism primarily reflects differences in glycosylation, although indels also occur in the predicted polypeptides. Using RNA interference (RNAi), we suppressed expression of 120K to determine if it is required for S-specific pollen rejection. Transgenic SC N. plumbaginifolia × SI Nicotiana alata (S105S105 or SC10SC10) hybrids with no detectable 120K were unable to perform S-specific pollen rejection. Thus, 120K has a direct role in S-specific pollen rejection. However, suppression of 120K had no effect on rejection of N. plumbaginifolia pollen. In contrast, suppression of HT-B, a factor previously implicated in S-specific pollen rejection, disrupts rejection of N. plumbaginifolia pollen. Thus, S-specific pollen rejection and rejection of N. plumbaginifolia pollen are mechanistically distinct, because they require different non-S-RNase factors.