Investigation on occurrence and ultrastructure of the proteinaceous nuclear inclusions (PNIs) in the Bignoniaceæ, with special reference to the geographic distribution patterns

SUMMARY

This paper analyzes the occurrence and distribution of Proteinaceous Nuclear Inclusions (PNIs) in the family Bignoniaceæ. 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 Tecomeæ and all taxa of Crescentieæ, Coleeæ, Oroxyleæ, Eccremocarpeæ and Schlegeliæ show PNIs. In most Bignonieæ they are lacking. The occurrence of PNIs in two tribes considered to be the oldest groups of Bignoniaceæ and related to the ancestral stock of Tubifloræ, Tecomeæ and Oroxyleæ, support their presence as an ancestral trait. Although systematic conclusions in Bignoniaceæ cannot to be made in consequence of the great structural homogeneity of PNIs, the relationships between occurrence data and geographic distribution patterns, are discussed. Finally, the placement of Schlegelia and Paulownia, regarded as transitional genera between Bignoniaceæ and Scrophulariaceæ, are analyzed.