Restabelecimento do potencial embriogênico de suspensões celulares e ajustes metodológicos para mutagênese em bananeira

Abstract

The mutation has been used in replacement of conventional system in improvement in banana sterile. However, to the success of in vitro mutagenesis indispensable the establishment of reproducible protocols in vitro regeneration of plants and optimization mutagenic treatments. This work was developed at Embrapa Cassava and Fruits, aiming to adjust mutagenesis techniques in order to be employed in cell suspensions and embryogenic callus banana, seeking to adapt the mutation induction methodology via Gamma radiation means and ethyl methane sulfonate (EMS). The work was subdivided into three chapters: in the first was developed a methodology for recoveryring of embryogenic capacity of cell suspensions with a high concentrations of nonembryogenic cells, which have been grown for more than three years; which also provided a continuous maintenance of embryogenic callus production for a long-term period in order to obtain cell suspensions and plant regeneration of these suspensions; in the second chapter adapted to adapt the mutation induction methodology, via gamma irradiation, to embryogenic callus (EC) and cell suspensions (CS) of banana 'Tropical' (AAAB) and 'Terra Maranhão' (AAB); while in the third chapter was adjusted up an in vitro mutagenesis inducing methodology via ethyl methane sulfonate (EMS) for examining the survival and plant regeneration rates from EC treatment and SC banana. Effective responses in growth and multiplication of new embryogenic callus are obtained with 0.50 mg L-1 2,4-D in the culture medium at every two-months subculture. The use of the fluorescein diacetate DF revealed the presence of viable embryogenic cells with significant regeneration of plants in these culture conditions. Thus, the methodology developed in this study, enables rescue the embryogenic potential the embryogenic potential of non-embryogenic cell suspensions of extended crops and induce new embryogenic cells with the use of 2,4-D. It was recorded that that increasing doses of gamma radiation caused reductions in the parameters under study. Independent of the cultivar used, doses of 100 Gy and 200 affect negatively the germination of somatic embryos from embryogenic callus as well as the number of root and the length plants. All these variables cell suspensions were reduced at the doses from 60 to 200 Gy. The increasing gama radiation doses caused a reduction in the length of the plants and in the survival rate. The efficiency of this radiation methodology in embryogenic callus and cell suspensions brings perspectives on the use of in vitro mutagenesis for the banana improvement. Embryogenic callus of the cultivar Terra Maranhão are more sensitive to the effects of EMS mutagenic, compared to cell suspensions. While in 'Tropical', the cell suspensions are more sensitive in relation to EMS treatments than embryogenic callus. This study shows a rapid and efficient methodology for in vitro mutagenesis via EMS application with the possibility of the propagation of promising mutants.