Análise molecular em variedades botânicas de Hancornia speciosa Gomes (Apocynaceae)

Abstract

The genus Hancornia is monotypic whose species is called Hancornia speciosa Gomes (mangabeira). It is a fruit native to Brazil that plays a relevant role in the tropical fruit market. Six botanical varieties are described according to morphological differences: var. speciosa, var. pubescens, var. gardneri, var. maximiliani, var. lundii and var. cuyabensis. However, the difficulty in distinguishing them in natural populations suggests that these botanical varieties are variations due to ecological adaptations. In this sense, the construction of the phylogeny of the genus allows to elucidate the taxonomic classification. Among molecular methods, the use of standard regions (DNA barcoding) is characterized by being safe and promising in phylogenetic studies. This study aimed to study the phylogeny of the genus Hancornia using plastid sequences (trnH-psbA, rbcL and matK). Leaves were collected in the States of Sergipe, Pernambuco, Paraíba, Maranhão, Ceará, Bahia, Goiás, Minas Gerais and in the Germplasm Collection of the Federal University of Goiás. DNA was duly extracted and PCR reactions and sequencing of genome chloroplast were performed. The trnH-psbA intergenic region identified eleven haplotypes. The phylogenetic tree showed the formation of two clades: one for speciosa variety and one for pubescens, gardneri and cuyabensis, demonstrating that the latter are genetically closer. A similar result was obtained in the principal component analysis where it reveals that speciosa forms a distinct grouping of the other varieties studied. This fact may be a consequence of isolation by distance since this variety occurs only in the Atlantic Forest and Caatinga. Thus, the evolutionary relationship between the varieties evidences the formation of two genetic groups, one for speciosa and another for gardneri, cuyabensis and pubescens, and it was revealed that gardneri possibly a natural hybrid between cuyabensis and pubescens. In addition, the absence of the varieties maximiliani and lundii is shown, showing only variations due to the environment. Therefore, only three botanical varieties should be considered for H. speciosa: pubescens, cuyabensis and speciosa.