Poliaminas na embriogênese somática em cenoura (Daucus carota L.)

Abstract

RESUMO: As poliaminas, putrescina (put), espermidina (spd) e espermina (spm) são amplamente distribuídas na natureza, desempenhando importante papel em vários eventos celulares. Considerando que as poliaminas estão envolvidas no processo embriogênico, torna-se importante conhecer as bases para estas alterações no metabolismo. O objetivo do presente trabalho foi observar os teores de poliaminas durante as diferentes fases da embriogênese somátka da cenoura. As análises foram realizadas, através da modificação do método de Flores e Galston a cada 96 horas durante 50 dias da cultura de células em suspensão. As células foram obtidas a partir de calos e inoculadas em meio de Murashige & Skoog (MS), modificado e acrescido de 0,2 mg/1 de 2,4-D e 0,1 mg/1 de cinetina durante os primeiros 14 dias da cultura, sendo que no restante do período permaneceram em meio MS desprovido de fiorreguladores. Os teores de poliaminas oscilaram durante todo o processo embriogênico, sendo que a putrescina foi a que apresentou maior acúmulo. Estes resultados sugerem que os níveis de espermidina e espermina são reduzidos em relação a putrescina devido a intensa utilização da spd e spm no processo de divisão e diferenciação celular, enquanto que a put parece ter apenas a função de sintetizar as outras duas amidas. Descritores: poliaminas, embriogênese somática, cenoura, Daucus carola POLYAMINES IN SOMATIC EMBRYOGENESIS IN CARROT (Daucus carota L.)ABSTRACT: The polyamines, putrescine (Put), Spermidine (Spd) and Spermine (Spm) are widely present in nature, performing an important role in various cellular events. Considering that polyamines take part of the embryogenic process, it is important to know the bases for these alterations in the metabolism. The objective of the present study was to observe the contents of polyamines during the different phases of somatic embryogenesis of carrot. Analyses were carried out, according to a modification of the method developed by Flores & Galston every 96 hours during 50 days from the culture of cell suspensions. The cells were provided from callus and inoculated in Murashige & Skoog (MS) medium which had been modified and added with 0.2 mg/1 of 2,4-D and 0.1 mg/1 of Idnetin during the first 14 days, whereas for the other days, they were kept in MS medium deprived of phytoregulators. The contents of polyamines varied during all the embryogenic process, when putrescine showed the most accumulated. These results suggest that the levels of Spermidine and spermine are reduced in relation to putrescine due to the intense use of Spd and Spm in the process of cell division and differentiation, whereas Put seems to have only the function of synthetizing the other two amines.

DNA demethylation and decrease on free polyamines is associated with the embryogenic capacity of Pinus nigra Arn. cell culture

“…These facts could be related with PAs functions attributed by diverse authors in researches made in angiosperms (Berros et al 1997), and gymnosperms (Minocha et al 1999). If it is admitted that Put favours cell division (Schons and Brasil 1995), its high levels in LNE fit in the callogenic character without embryogenic feature of this line.…”