Tissue printing and its applications in self-incompatibility studies

In this study, the tissue printing technique has been used to rapidly localize in female tissues the presence of specific mRNA representing the products (or some of the products) of the self-incompatibility S-locus gene(s). The methodology, initially developed for Brassica oleracea (sporophytic self-incompatibility) has been successfully employed on Solanum chacoense (gametophytic self-incompatibility). In the Brassica system tissue printing has allowed rapid discrimination between S alleles belonging to class 1 (dominant types) vs. class 2 (recessive types), and thus parallels findings obtained by restriction analyses. In the Solanum system the level of the S-RNase messages was analysed by scanning laser densitometry, and it was found that the message levels of the allele S14 declined faster than those coming from S13 in mature flowers.