O presente trabalho teve como objetivo geral o estudo do papel de aminas no desenvolvimento in vivo e in vitro de tumores ?crown-gall? em gergelim (Sesamum indicum L.). As plantas de gergelim foram cultivadas em soluções nutritivas de Hoagland e Arnon, variando-se os níveis de potássio. Os ?seedlings? foram inoculados com Agrobacterium tumefaciens, cepa virulenta B₆, e os tumores obtidos foram colhidos 30 dias após inoculação. Para se verificar a influência de putrescina no desenvolvimento dos tumores in vivo, 3 lotes de plantas obtidas como acima mencionado, receberam injeções de 0,0; 2,5 e 5,0 μM de putrescina - HCl, dois dias após a inoculação da bactéria. Explantes de tumores obtidos de plantas cultivadas em solução nutritiva completa (6 mM de potássio) foram inoculados em meio de cultura com várias doses de putrescina. Os aminoácidos (arginina, citrulina e ornitina), as aminas (agmatina, N-carbamilputrescina e putrescina), extraídos com etanol 80% de folhas intactas, caules e tumores, foram fracionados em resina de troca catiônica Amberlite IRC-50 (H⁺) e Dowex 50W X-8 (H⁺). Depois de isolados por cromatografia em papel de filtro foram feitas as determinações quantitativas. Os níveis de putrescina, espermina e espermidina foram determinados usando-se analisador automático de aminoácidos (Beckman, modelo 120C). Essas mesmas substâncias foram analisadas nos calos obtidos da cultura de tumores in vitro, por cromatografia em camada delgada usando-se densitômetro (Vitraton TLD-100) para se medir a intensidade de fluorescência. Os dados obtidos permitiram mostrar que também em tumores ?crown-gall? de plantas de gergelim, a deficiência de potássio foi crítica no aumento dos teores dos aminoácidos do ciclo da ornitina-uréia e das aminas correspondentes, principalmente putrescina. A relação molar entre putrescina e espermidina encontrada nos tumores in vivo pareceu indicar possível influência das poliaminas na indução e regulação da proliferação de células cancerosas. Também foi observado que putrescina, em determinadas doses, influenciou a formação de calos a partir de explantes de tumores ?crown-gall?, bem como o desenvolvimento dos tumores in vivo.

The objective of this work was to investigate the role of amines in vivo and in vitro in the development of tumors in ?gergelim? (Sesamum indicum L.). Seedlings of ?gergelim? (Sesamum indicum L.) were inoculated with Agrobacterium tumefaciens, strain B₆, and grown in the nutrient solution of Hoagland and Arnon at several concentrations of potassium (0.0; 6.0; 10.0; 20.0 mM) to study the effects of potassium on amine synthesis and tumor development. Tumors were harvested 30 days following inception for initiating plant tissue cultures and/or for chemical analysis. The tumor tissue cultures were maintained on PSR tissue culture medium. The influence of putrescine concentration on tumor development was studied in seedlings injected with specific concentrations of putrescine (0.0; 2.5; 5.0 μM). The injection was administered two days following the inoculation with Agrobacterium tumefaciens at a site apical to the bacterial inoculation. The amino acids (arginine, citrulline and ornithine) and amines (agmatine, N-carbamylputrescine and putrescine) were extracted from intact leaves, stems and tumors, with 80% ethanol and fractionated on cation exchange resins Amberlite IRC-50 (H⁺) and Dowex 50W X-8 (H⁺). After their subsequent separation by paper chromatography, each compound was determined quantitatively. The putrescine, spermine and spermidine concentrations were determined using a Beckman amino acid analyzer, model 120C. These substances were analyzed fluorimetrically for the tumor tissue grown in vitro. In crown-gall tumors, the endogenous concentrations of amino acids and amines, mainly putrescine, are significantly higher for plants grown in nutrient solution containing 0.0 mM of potassium compared to the 6.0; 10.0; 20.0 mM concentrations of potassium. The size of tumors are large for plants grown at the 0.0 and 6.0 mM concentrations of potassium being slightly larger in the latter. Chemical analysis reveals an almost three-fold increase in the endogenous putrescine/spermidine concentrations ratios in crown-gall tumor tissues as compared to normal tissues. Likewise, tumor tissues grown in vitro are characterized by high putrescine/spermidine concentration ratios which exceed those observed in vivo. Tumor tissues cultured on a medium supplemented with 0.25 μmoles putrescine undergo rapid cell proliferation and have an extremely high putrescine/spermidine concentration ratio of 15.94. The results suggest a possible role for the polyamines in the induction and regulation of cancer cell proliferation.