AN S-RNASE PROMOTER FROM NICOTIANA-ALATA FUNCTIONS IN TRANSGENIC N-ALATA PLANTS BUT NOT NICOTIANA-TABACUM

Nicotiana tabacum and Nicotiana alata plants were transformed with gen omic clones of two S-RNase alleles from N. alata. Neither the S-2 clon e, with 1.6 kb of 5' sequence, nor the S-6 clone, with 2.8 kb of 5' se quence, were expressed at detectable levels in transgenic N. tabacum p lants. In N. alata, expression of the S-2 clone was not detected, howe ver the S-6 clone was expressed (at low levels) in three out of four t ransgenic plants. An S-6-promoter-GUS fusion gene was also expressed i n transgenic N. alata but not N. tabacum. Although endogenous S-RNase genes are expressed exclusively in floral pistils, the GUS fusion was expressed in both styles and leaves.