Evolução cromossômica e de tamanho de genoma: estudos sobre a tribo dalbergieae (fabaceae, papilionoideae) e espécies amazônicas do clado Andira

Abstract

Within the Papilionoideae subfamily, the Dalbergieae tribe stands out in terms of number of species, a geographically comprehensive, taxonomically complex and genetically diverse tribe. In order to learn a little more about possible evolutionary events that generated genetic diversity in Dalbergieae, we carried out a reconstruction of the tribe's chromosome number and a reconstruction of the DNA content of one of its clades, the small Andira clade. To reconstruct the ancestral chromosome number of Dalbergieae, a survey of cytogenetic and molecular records in the literature was carried out and based on this, an ancestral reconstruction was carried out using ChromEvol. The results showed that polyploidy and dysploidy events were quite recurrent in the nodes that originated the tribe, and the evolution of the chromosome number of the three largest dalbergioid clades occurred from the ancestral number of x = 10; and for the small Andira clade that first diverged in the evolutionary history of the tribe, it was x = 11. In this clade that diverged early, genome size analyzes were conducted and excursions were carried out in several phytophysiognomies in the states of Pará and Amazonas, where Fresh leaf tissues were collected to estimate the 2C value using flow cytometry. A variation of almost 3× in DNA content was observed between the species analyzed, between 2C = 1.21 pg in Aldina discolor (Spruce) Benth and 2C = 3.56 pg in Hymenolobium heterocarpum Ducke (mean CV = 4.22 SD = 0.14). Genome sizes were obtained for 10 of the 73 species (13.69%) of the Andira clade, all being reported for the first time. With the data, we shed light on the main genetic and molecular evolution events of these groups.