VARIABILIDADE GENÉTICA E QUÍMICA ENTRE E DENTRO DE POPULAÇÕES DE Casearia sylvestris Sw. (SALICACEAE) NO ESTADO DE SÃO PAULO

This work aimed obtaining tools and information for the conservation and rational exploitation of Casearia sylvestris Sw. (Salicaceae), a tree species which produces casearins, pharmacologically important clerodane diterpenes. This goal was achieved through the development of a set of polymorphic microsatellite markers, and through the study of chemical and genetic diversity in populations of C. sylvestris from Sao Paulo State. Also, we aimed contributing for the debate on the existence of two varieties within this species (var. sylvestris e var. lingua). A genomic library was constructed and 10 primer pairs were obtained. Those primers were utilized for a population genetic structure analysis, in which 376 individuals from nine populations distributed on four different ecosystems (Evergreen Atlantic Forest, Semideciduous Atlantic Forest, Cerrado and ecotones) were sampled. The two varieties were sampled according to its distribution among these populations. Genotyping was performed at 700 and 800 nm by electrophoresis on an IR2-DNA Analyser (LI-COR). The data were analyzed through frequentist, Bayesian and coalescence-based approaches, through the use of several softwares. Chemical diversity was studied by sampling in the same populations (12 individuals per population, i.e. 108 individuals). Also, cuttings of these individuals were prepared, aiming to verify its’ chemical compounds after a year of green-house cultivation. Cuttings’ rooting was problematic and a methodology was developed. Only 46 cuttings survived. Casearins from these 154 individuals (108 + 46) were extracted and analyzed by HPLC. Genetic analysis results suggests a partial genome duplication, as more than two alleles for the same locus were observed in 8% of var. sylvestris individuals and in 70% of var. lingua individuals. Additional studies are necessary to verify the hypothesis of partial genome duplication. It was observed that the populations harbouring the two varieties present higher levels of genetic diversity. Gene flow among ecosystems showed to be reduced. Analysis of molecular variance showed that 76% of the total genetic diversity sampled is attributable to differences among individuals within populations, and that varieties’ genetic divergence is higher than that observed among ecosystems or populations. Bayesian clustering successfully assigned individuals to varieties, evidencing important genetic differences between these taxa. Results suggest that the two varieties are relatively independent units, which met only in the ecotones, where hybridization takes place. The maintenance of two distinct taxa face to gene flow and hybridization is discussed. Chemical analyses revealed great casearins’ diversity, even within a single individual. Each population presents a pattern of casearins diversity, which is different from the others populations’ pattern. Varieties also showed to be differentiated. Results revealed that a year of green-house cultivation was not enough to homogenize the casearins’ production from individuals originated from different localities. This result suggests a great importance of the genotype for casearins production.