Caracterização genômica e molecular do guaranazeiro (Paullinia cupana var. Sorbilis)

Abstract

Paullinia cupana is originary from Amazon and is divided in two different varieties, P. cupana var. cupana (Venezuela and Colombia) and P. cupana var. sorbilis (Brazil), this last one is the true guarana plant. The few studies on this plant are concentrated, mainly, in its bothanical aspects and effects of its seed extract over some medical experimentation. The main objective of this work was to amplify knowledgment over those informations about the guarana plant, moreover by the means of genetic molecular. Aiming the following propositions: (1) to determine the guarana plant (P. cupana var sorbilis) caryotype and its genome size; (2) to characterize and validate sequences expressing in the guaraná berries, gathering especial information on those related with caffeine synthesis (N-methil-transferases); (3) to determine its (Nmethil- transferases) copy number in the plant genome; (4) to determine its (N-methiltransferases) expression patterns in different organs/tissues. The results showed an elevated number of chromosomes (210) and DNA content (2C = 22.5 pg DNA/cell). The caryogram analysis presented two sets of chromosomes, one tetraploid and other hexaploid. The transcripts sequencing yield a 15,387 ESTs databank, grouped in 2,628 contigs and 5,969 singletons. Among these are enzymes genes involved in caffeine synthesis, the so called caffeine sintases. The analysis of these guarana sequences (denominated GNMT) shows it is homologous to N-methyltransferases of other species such as coffee (Cofea arábica and C. canephora), cocoa (Theobroma cacao), and green tea (Camellia sinensis). Regarding to the number of genome copies, the guarana plant presented three times more than its native wild plants (the guaranaranas, Paullinia sp) correlates. Fruits posses the highest level of GNMT transcript expression when it reach 70 days of development age, increasing the rate as berries ripening process occurs. These results are especially interesting and can collaborate with the experimentations in progress course which are proving the healing properties attributed to this plant and its seed powder extract.