Multiplicação clonal e calogênese em tecidos embrionários de feijão-fava (phaseolus lunatos L.) var. branca

Abstract

Lima bean (Phaseolus lunatus L.) is a climbing plant in the Fabaceae family, considered a second most important species of its genus. It has been considered a source of income and alternative food for part of the population of the Northeast Brazil, where it is widely consumed. However, there are few studies on the genetics and improvement of lima beans, and in vitro cultivation studies are extremely important for the genetic understanding of the culture, with a view to obtaining new varieties. The objective of this work was to establish initial protocols for the introduction, establishment and in vitro multiplication of white lima beans (P. lunatus L.) and to induce calluses in embryonic tissues with a view to future studies of cell suspensions for organogenesis and somatic embryogenesis of the species. The work was conducted at the Plant Biotechnology Laboratory (BIOVEG) of CECA / UFAL. Seeds of lima beans (P. lunantus L.) cv. Branca were obtained from rural producers in a open market in the municipality of São Miguel dos Campos - Alagoas. After sorting, cleaning and disinfesting seeds, the embryos were extracted in a laminar flow chamber with the aid of tweezers and scalpels. The excised embryos were transferred to MS culture medium with different concentrations of benzylaminopurine (BAP) and indole butyric acid (AIB). Growth and multiplication of the explants were evaluated during 60 days in cultivation. In a second experiment, callus induction in zygotic embryos was evaluated for different 2.4 D concentrations in light and dark conditions. The results showed that the highest concentrations of BAP (1.0 and 2.0 mg L -1 ) were able to multiply up to more than 10 times the number of shoots of the control (without BAP). The use of 0.5 mgL-1 of IBA was able to induce adventitious roots only in explants with little (0.5 mg L -1 ) or no BAP, indicating for a micropropagation system in two distinct stages - multiplication and rooting. All of the 2.4 D concentrations used (10, 20, 30, 40 and 50 mg L -1 ) readily induced a good mass of callus only in explants that were kept in the dark, but not in explants kept in a lighted environment. This work showed that micropropagation and callogenesis lima bean cv. Branca will serve as important tools in the genetic improvement and transformation of the species. Index terms: Fabaceae; fabric culture; culture of embryos; auxins; cytokinis.