J. Murfett et al., ANTISENSE SUPPRESSION OF S-RNASE EXPRESSION IN NICOTIANA USING RNA-POLYMERASE-II-TRANSCRIBED AND RNA-POLYMERASE-III-TRANSCRIBED GENE CONSTRUCTS, Plant molecular biology, 29(2), 1995, pp. 201-212
In the Solanaceae, self-incompatibility is controlled by a single, mul
ti-allelic ('S') locus. One product of this locus is a ribonuclease, t
he S-RNase, which is expressed predominantly in mature pistils and has
recently been shown to cause allele-specific pollen rejection in tran
sgenic plants. Hybrid Nicotiana phumbaginifolia x N. alata plants were
used to test the effects of antisense suppression of the S-A2-RNase f
rom N. alata using three different gene constructs: two driven by RNA
polymerase II-transcribed promoters, and the third, containing a trunc
ated soybean tRNA(met-i) gene, transcribed by RNA polymerase III. All
three constructs caused suppression of S-RNase activity in the transge
nic plants. Unexpectedly, the CaMV 35S promoter was more effective for
antisense suppression than the tissue specific tomato ChiP promoter.
Antisense suppression of S-RNase correlated with low sense S-A2 transc
ript levels and high antisense S-A2 transcript levels. Untransformed h
ybrids that contained the N. alata S-A2 allele were incompatible with
N. alata S-A2 pollen, while transgenic plants with suppressed S-A2 gen
e expression accepted the pollen. The utility of this hybrid plant sys
tem for studying some aspects of antisense gene suppression is discuss
ed.