SELEÇÃO DE PRIMERS ISSR E ESTRUTURA GENÉTICA POPULACIONAL DE Baccharis crispa SPRENG. (ASTERACEAE) DO SUL DO BRASIL

Abstract

Baccharis crispa Spreng., popularly known as "carqueja", is a herbaceous species of the Asteraceae family. The species is widely used in folk medicine is also used in brewery as a substitute for hops. Also has ecological importance because it is a pioneering plant and operates in the maintenance of pollinators. Considering these aspects, B. crispa was selected as a priority species for study management and conservation in the Atlantic Forest biome by Brazilian Government. Despite this, little is known about genetic diversity of the species. Thus, this study aimed to the selection of primers ISSR (inter simple sequence repeat) and analysis of populations genetic structure of the Carqueja from the South of Brazil. For the ISSR primers screening, 42 primers were evaluated in a population of 20 individuals. For each primer the PIC (Polymorphic information Content), MI (Index Marker Index) and RP (Resolution Power) indices were calculated. PIC values ranged from 0.27 to 0.45, from 4.87 to 12.37 MI and RP 2.2 and 11.57. With these data we selected 15 primers with the highest values for all three indexes. These primers were run on seven populations of B. crispa derived from the states of Paraná, Santa Catarina e Rio Grande do Sul. With the ISSR data several genetic index were measured for the studied populations. The average genetic similarity within each population ranged from 0.27 to 0.54 with an average of 0.20 for all populations, showing high variability. The analysis of molecular variance (AMOVA) showed that most variation occurs within populations (0.56) than among populations (0.43), which is expected in allogamic plant populations. The Shannon diversity index (0.26) and Nei`s genetic diversity (0.41) also shows high genetic variability in populations. The grouping of individuals by Jaccard coefficient using UPGMA formed seven groups, corroborating the number of populations. The Mantel test showed a positive correlation (r = 0.44) between geographic distance and genetic distance. The fixation index (Fst) was 0.43. The clustering, correlation and the observed Fst shows that the populations are structured. The pattern distribution of locos showed that the populations of Parana and Santa Catarina, exhibit more variability, confirming the diversity index calculated. The joint analysis of the results shows that there is high genetic varibility in B. crispa and that regions of the Middle-South Paraná (Guarapuava and General Carneiro Region) and Middlewest of Santa Catarina (Joaçaba and Campos Novos Region) are centers of species diversity. The observed data still seem to indicate that the conversion of forest to pasture favors the species and when in agricultural areas, disadvantages the species. These data are novel to B. crispa and will going to contribute to the understanding of the evolutionary aspects of the species and the development of strategies for the sustainable cultivation and conservation of this species.