Unveiling the foliar development's ontogenetic basis in Pilocarpinae (Rutaceae, Sapindales)

• Grant number: 25/03975-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: June 01, 2025
• End date: October 31, 2028
• Field of knowledge: Biological Sciences - Botany - Plant Morphology
• Principal Investigator: Gladys Flávia de Albuquerque Melo de Pinna
• Grantee: Willian Duarte Silva Filho
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Despite significant progress in understanding the ontogeny of foliar structures, numerous questions remain that necessitate further investigation. The family Rutaceae is one of the most species-rich within the order Sapindales. Within its subfamilies, the tribe Galipeeae (Zanthoxyloideae) represents the largest group of species in the Americas, comprising 33 genera and 246 species. This tribe is subdivided into two subtribes: Galipeinae (27 genera, 131 species) and Pilocarpinae (6 genera, 63 species). Galipeeae exhibits considerable diversity in foliar morphology, including palmately or pinnately compound leaves (both imparipinnate and paripinnate), with 1-3-(5-7) leaflets, unifoliate leaves, and/or simple leaves, in addition to instances of heterophylly. The following species were selected for study: *Esenbeckia cowanii*, *E. febrifuga*, *E. oligantha*, *E. pilocarpoides pilocarpoides*, *E. pilocarpoides maurioides*, *Pilocarpus carajaensis*, *P. giganteus*, *P. grandiflorus*, *P. trifoliolatus*, *Conchocarpus toxicarius*, and *Casimiroa edulis*, representing a range of foliar patterns. The specific objectives of this project are as follows: 1) to investigate the incidence of aborted leaflets in compound leaves; 2) to examine the vascular plexus characteristics of lateral leaflets in the swollen regions of compound leaves; 3) to analyze instances of heteroblasty and heterophylly within *Pilocarpinae*; 4) to explore the influence of adaxial/abaxial polarity on foliar ontogeny; and 5) to compare the results of foliar ontogeny in *Pilocarpinae* with those of palmately compound representatives of Zanthoxyloideae. The collected material will be subjected to classical plant anatomical techniques, including scanning electron microscopy and optical microscopy. The study is expected to yield original publications, with results that contribute to the elucidation of foliar development in Rutaceae. When integrated with ongoing studies on other groups, these findings will enhance our understanding of the evolutionary processes underlying foliar patterns in Sapindales. (AU)