Gymnosperm B-sister genes and ovule/seed development

Seeds are produced by gymnosperms and angiosperms but only the latter have an ovary to be transformed into a fruit. Lovsisetto et al.  study B-sister genes from two gymnosperms, Ginkgo biloba and Taxus baccata, and find that in Ginkgo the gene is involved in the growth of ovular-derived fleshy fruit. They functionally characterize the gene by ectopically expressing it in tobacco. In contrast, the fleshy structure in Taxus derives from an outgrowth of the ovule peduncle, and the B-sister gene is not involved in its growth. They suggest that B-sister genes have a primary function in ovule/seed development and a subsidiary role in the formation of fleshy fruit-like structures when the latter have an ovular origin, as observed in Ginkgo.