Conservação in vitro da aroeira (myracrodruon urundeuva fr. Allemão) e estabelecimento in vitro da baraúna (schinopsis brasiliensis engl.)

Abstract

Aroeira and baraúna are on the official list of Brazilian plant species threatened with extinction and tissue culture can be used for the conservation and micropropagation of these species. However, the objective was to evaluate the in vitro conservation of aroeira by slow growth with later resumption of growth, compare chemical treatments in asepsis of mastic nodal segments; test growth regulators in the establishment of aroeira; analyze different cytokinins in different concentrations and zeatin combined with auxins in the establishment and development of barauna; and verify ethylene inhibitors on the development and leaf abscission of barauna. The experiments with aroeira and Baraúna were carried out, respectively, at the Biotechnology Laboratory in Uberlândia-MG and at Embrapa Semiárido (Petrolina-PE). In the preservation of aroeira the culture medium MS (50%) was used and evaluated: osmoregulators: mannitol and sorbitol in concentrations 10 and 20 g L-1 and sucrose in concentrations 30 and 40 g L-1 added to the medium in the first experiment. In the second, the concentrations of mannitol and sorbitol were reduced to 5 and 10 g L-1 compared to each other and to the plant regulator and abscisic acid to 1,0 and 2,0 mg L-1. Subsequently, the polyamines: putrescine, spermine and spermidine in concentrations 0,5 and 1,0 mg L-1 were tested to establish the aroeira. In the barauna experiments, the WPM medium was used. For the multiplication two experiments were carried out, in the first zeatin (ZEA) and 6-benzylamino purine (BAP) were compared in concentrations 0; 0.1; 0.2; 0.4; 0.8 and 1.0 µL-1, and in the second zeatin (ZEA) at concentrations 0.2; 0.4; 0.8 and 1.0 µL-1 concentrations of 0,1 were combined; 0.2; 0.4 and 0.5 µL-1 of 3-indolacetic acid (IAA), naphthalene acetic acid (NAA) and indolbutyric acid (IBA). Finally, ethylene inhibitors silver nitrate and cobalt chloride at concentrations of 5; 10; 20 and 40 µM were compared to reduce leaf abscission in barauna. In the conservation stage, sucrose at a dose of 40 g L-1 added to the culture medium increases the amount of calluses and reduces the survival of mastic explants and mannitol negatively affects the resumption of growth of explants. The polyamine spermine promotes the growth of the aerial part and in the concentration 0,1 mg L-1 provides greater number of leaves and root length. From 0,2 µL-1 of NAA and 0,4 µL-1 of ZEA, a greater number of barauna shoots occurs. IAA is the most suitable auxin to be associated with ZEA for longer shoot length and number of buds. The length of the shoots and number of buds are not influenced by silver nitrate and cobalt chloride at the concentrations evaluated. At concentrations of 5 and 10 µM, cobalt chloride is more efficient than silver nitrate for reducing leaf abscission in barauna. Silver nitrate from a concentration of 20 µM completely avoids leaf abscission while cobalt chloride has a maximum reduction in abscission at a concentration of 40 µM