Investigation on occurrence and ultrastructure of the proteinaceous nuclear inclusions (PNIs) in the Bignoniaceæ

SUMMARYThis paper analyzes the occurrence and distribution of Proteinaceous Nuclear Inclusions (PNIs) in the family Bignoniaceae. In 52 out of 70 examined species (corresponding to 74.2%) nuclear inclusions with lamellar substructure are observed. An additional crystalline body, derived by packing of lamellar inclusion subunits during cell development, is reported in several taxa. PNIs are recorded in all studied tribes, but with different distribution. Most Tecomeae and all taxa of Crescentieae, Coleeae, Oroxyleae, Eccremocarpeae and Schlegeliae show PNIs. In most Bignonieae they are lacking. The occurrence of PNIs in two tribes considered to be the oldest groups of Bignoniaceae and related to the ancestral stock of Tubiflorae, Tecomeae and Oroxyleae, support their presence as an ancestral trait. Although systematic conclusions in Bignoniaceae cannot to be made in consequence of the great structural homogeneity of PNIs, the relationships between occurrence data and geographic distribution patterns, are discussed. Fin..