GENETIC DIVERSITY AND POPULATION STRUCTURE OF Helosis brasiliensis Schott & Endl. (Balanophoraceae) IN RIO GRANDE DO SUL, BRAZIL

Abstract

Helosis brasiliensis (Balanophoraceae) is a holoparasitic herb of plant roots. Its inflorescence measures about 5 to 10 cm, and can only be identified during the breeding season, in the warmer months of the year. It is found on plant litter, with little light incidence, near streams and rocks. Until recently, H. brasiliensis was considered a synonym of H. cayennensis. In recent revisions, they were segregated from each other with H. brasiliensis being restricted to the South and Southeast of Brazil, while H. cayennensis occurs in other regions of the country. Therefore, there are no studies on the genetic diversity of this species. The aim of this work was to evaluate the genetic diversity and population structure of H. brasiliensis in Rio Grande do Sul, using two types of molecular markers: ITS and ISSR. Four populations, located in Silveira Martins, Passa Sete, Candelária and Teutônia were sampled. Afterwards, the samples were taken to the Laboratory of Plant Genetics and Evolution at the Federal University of Santa Maria, where total DNA was extracted and PCR reactions with two molecular fragments were performed. The samples amplified with the ISSR fragments were standardized in agarose gels, put into Excel spreadsheets, and analysed in GenAlEx and Structure X software. Samples amplified with ITS nuclear fragments were purified with PEG (polyethylene glycol), were sequenced, and analysed in the MEGA software. The results obtained revealed moderate levels of genetic diversity within populations, and five genetic groups were identified by Structure analysis. Overall, the species has moderate levels of genetic diversity (I= 0.411-0.529) and high polymorphism (75 - 89.42%). The molecular markers used were efficient to access the genetic diversity of the species, characterizing high levels of diversity and affinities among genetic groups.