Organogênese e criopreservação in vitro de Handroanthus serratifolius (Vahl) S. O. Grose

Abstract

Handroanthus serratifolius tree is typical of the Cerrado biome. Presents medicinal, ornamental and timber properties. The tissue culture is an alternative to the plant propagation and cryopreservation is an efficient way to long-term storage in liquid nitrogen (LN) at -196 ° C. The objectives of this work were to study the in vitro organogenesis and the cryopreservation of H. serratifolius. For in vitro germination, zygotic embryos were decontaminated in sodium hypochlorite for different periods and inoculated in MS medium. The effect of different BAP concentrations on shoot induction and regeneration of apices on WPM medium was investigated. For regeneration of shoots from roots, hypocotyl and radicle segments were inoculated in WPM plus IAA. The effect of different IBA concentrations on rooting and acclimatization were evaluated. For seeds cryopreservation, the efficiency of different thawing times (1, 3 or 5 minutes) regarding to germination, fresh and dry weight of seedling was verified. After cryopreservation, seeds were decontaminated in 2% sodium hypochlorite (P1), or embryos decontaminated with sodium hypochlorite 1% (P2) prior inoculation on MS containing GA3. The germination percentage and shoot length of P1 and P2, fresh and dry weight (mg) of shoots and roots of seedlings originated from the P2 were investigated. For embryos cryopreservation, after disinfection and dehydration in laminar air flow (0 to 300 min) chamber, the material was stored for seven days in NL, thawed in a water bath to 38 °C for 1 to 5 minutes, inoculated medium MS containing GA3 and the germination percentage and shoot length were evaluated. For shoot tips cryopreservation, different exposure times (0, 15, 30, 60, 120 and 240 min) on PVS2 at 0 °C, before plunge into LN, and the apices regrowth were evaluated. The use of sodium hypochlorite (1%) is effective in decontaminating embryos. For shoot induction and shoot tips regeneration, 2μM BAP promoted the best results. Shoots were regenerated from hypocotyl and roots segments with difference among treatments. The IBA concentration tested were effective for root induction. Acclimatization was efficient with 100% acclimatized plants. Thawing for one minute is effective for seeds cryopreservation. Only 10% of seeds (P1) germinated, while embryos (P2) presented 95% germination after cryopreservation. Embryos showing water content of less than 10% before exposure to LN presented 85% germination. The higher regrowth rate for cryopreserved shoot tips was 54.8% after exposure for 30 minutes in PVS2 solution.