Exploring the complexity, evolution and ontogenetic bases of the primary shoot system

• Grant number: 24/04123-4
• Support Opportunities: Regular Research Grants
• Field of knowledge: Biological Sciences - Botany - Plant Morphology
• Principal Investigator: Gladys Flávia de Albuquerque Melo de Pinna
• Grantee: Gladys Flávia de Albuquerque Melo de Pinna
• Host Institution: Instituto de Biociências (IB). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated researchers: Gerhard Zotz ; José Rubens Pirani ; Marcelo Rodrigo Pace ; Otávio Luis Marques da Silva ; Thiago Jose de Carvalho Andre ; Thomas Haevermans ; Vania Nobuko Yoshikawa
• Associated scholarship(s): 24/17866-5 - Exploring the complexity, evolution and ontogenetic bases of the primary shoot system, BP.TT

Abstract

The proposal explores leaf ontogenesis in monocotyledons and eudicotyledons, highlighting their structural diversity. In monocotyledons, structures such as ligule, pseudopetiole, pseudobulb, and mucron will be discussed in terms of their ontogenetic development and evolutionary implications. In the context of eudicotyledons, simple and compound leaves will be discussed, with examples from different families that exhibit this structural diversity, such as Rutaceae, Burseraceae, Meliaceae, Simaroubaceae, Malvaceae, Euphorbiaceae, and Bignoniaceae. Although these are topics already addressed in the literature, this proposal stands out for the importance of conducting a comparative study of leaf development in understanding the evolution of structures, filling gaps in the knowledge of the primary stem system. Contextualization and scientific challenges are presented in two subprojects: 1) Development of unifoliolate leaves, involving species from Rutaceae, Meliaceae, Simaroubaceae, Euphorbiaceae, Bignoniaceae, and Malvaceae, whose main challenge lies in investigating the incidence of aborted leaflets during leaf ontogenesis and characterizing swellings or articulations at the apex of the petiole and investigating the stages of early foliolate leaves or late unifoliolate leaves. In the second subproject entitled Development of the stem system in monocotyledons, the central challenge is to recognize the laminar or leaf-like nature of structures such as mucron, ligule, pseudopetiole, and pseudobulb. In this second subproject, representatives of six families were selected: Commelinaceae, Costaceae, Cyperaceae, Orchidaceae, Poaceae, and Zingiberaceae. Because this is a multidisciplinary and broad approach proposal, ontogenetic studies will be conducted on selected species based on the literature record of the character to be studied. In these analyses, samples will be collected and subjected to conventional light microscopy (LM) and scanning electron microscopy (SEM) techniques. In the case of unifoliolate leaf study, we will also perform analyses using computerized microtomography (Micro-CT). In addition to the species to be studied in ontogenetic characterization, a character matrix will be constructed for each group, whose DNA sequences will be aligned using MAFFT software v.7.215 and topology reconstructions will be performed based on current phylogenies through a Bayesian approach using MrBayes software v.3.2. Through the MrBayes program output, a consensus tree will be produced, considering the first 25% of trees as burn-in, which will be compared with the most recent topologies present in the literature to look for incongruences. Ancestral state reconstructions of each studied character will be performed in R software v.4.2.1 using the ape, evobiR, phytools, phangorn, and especially corHMM packages. Three maximum likelihood models will be tested: ER (equal-rates model), SYM (symmetric model), and ARD (all-rates-different model), performing 1000 random restarts for each model. The ability of the models to explain the data will be evaluated based on the Akaike Information Criterion. Additionally, a second model will be used for ancestral state estimation: stochastic character mapping through the phytools package. The model with the most significant optimality criterion from the previous analysis (ER, SYM, or ARD) will be used for 1000 stochastic mappings, which will be summarized into a single topology. The two major approaches, ontogenetic and evolutionary, will be analyzed together with the involvement of a team of national and international researchers recognized for their expertise in their respective areas, strengthening the quality and robustness of the research, but also promoting access to botanical collections and facilities in advanced research laboratories, resulting in a broader and more global understanding of the investigated characters. (AU)