Ultrastructural relationships between chlorenchyma and phloem cells in peripheral vascular bundles in leaves of Aizoaceae (Caryophyllales)

• Grant number: 22/12130-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2022
• End date: February 28, 2025
• Field of knowledge: Biological Sciences - Botany
• Principal Investigator: Gladys Flávia de Albuquerque Melo de Pinna
• Grantee: Guilherme Tamassia Garcia
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 23/17492-5 - Anatomical patterns, ultrastructure and phloem loading in peripheral vascular bundles in leaves of Aizoaceae (Caryophyllales), BE.EP.IC

Abstract

The family Aizoaceae (Caryophyllales) is represented by a large number of succulent species, which can water-storage in all photosynthesizing cells, or present a distinction between water-storage parenchyma and chlorenchyma, being called all cell and storage cell succulents, respectively. In many species of Aizoaceae peripheral vascular bundles occur around the central rib, which may have phloem turned to the center of the leaf (exoscopic) or to the epidermis (endoscopic), the latter being the predominant in the family. In the present project we selected the species Sesuvium portulacastrum (L.) L. (Sesuvioideae), a storage cell with exoscopic bundles and Delosperma napiforme Schwantes (Ruschioideae), also storage cell but with endoscopic bundles as anatomical models for the first ultrastructural study of peripheral phloem cells and their relationships with the chlorenchyma. Our objectives are: 1) to analyze whether ultrastructural specializations occur in phloem cells in endoscopic bundles in a storage cell species whose phloem is associated with chlorenchyma; 2) to compare the ultrastructural characteristics with exoscopic bundles of S. portulacastrum, whose phloem is closer to the water-storage parenchyma. The material will be submitted to transmission electron microscopy analyses. Thereby, it is expected to obtain relevant information on the role of peripheral bundles in the efficiency of phloematic loading in succulent leaves of Aizoaceae.