InduÃÃo de mutaÃÃo em feijÃo-caupi [Vigna unguiculata (L.) Walp., cultivar BR-14 mulato, visando à obtenÃÃo de mutantes tolerantes à salinidade

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Among cultivated bean varieties cowpea [Vigna unguiculata (L.) Walp.] stands out for its high protein content and its ability to grow under adverse conditions. As such, this species has become one of the most important subsistence crops for rural populations in Brazilian north-eastern region. However, aside from increasing environmental problems, soil salinity has caused crop productivity to decline due to inadequate irrigation. Biotechnological methods as in vitro mutagenesis provide an alternative for developing adapted cultivars. In this study in vitro mutation was induced using gamma rays, in order to generate salinity tolerant cowpea varieties. The BR14-Mulato cultivar was selected, having demonstrated satisfactory in vitro regenerative capacity in previous studies also recognized as an important cultivar for the Brazilian north-eastern region. The second step was to establish an appropriate protocol for in vitro cultivation of irradiated seeds under selection pressure by determining the maximum concentration of NaCl that would impair regeneration. The concentrations used were 172 mM (1% - Treatment 1), 258 mM (1.5% - Treatment 2), 344 mM (2% - Treatment 3) and 0 mM (Negative Control) the result being a concentration of 172 mM. Finally, the seeds were irradiated with three dosages of gamma radiation (100 Gy, 150 Gy e 200 Gy), and control material (0 Gy). Their tissues were simultaneously isolated and inoculated in vitro in media with and without salt. As a result, a somaclonal variant was generated from non-irradiated material (0 Gy) and inoculated in a non-selective medium, being transferred and surviving to a medium containing NaCl. The other significant result of this study was the generation of a mutant induced by a dosage of 150 Gy which initially formed an embryogenic callus in the absence of NaCl. In the next step, it was grown under selection pressure and verified for possible mutation and prepared through root induction for future field and molecular analysis. The results of this study add support to the development of well established protocols for further studies in the regeneration and induction of in vitro mutation, with the probable mutants (induced or spontaneously generated) offering the possibility of generating a variety able to tolerate salinity

ASSUNTO(S)

ciencias biologicas cultura de tecidos raios gama in vitro mutagenesis tissue culture salinity legumes leguminosas gamma rays mutagÃnese in vitro

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