Resumo

CARO, Luis; MARINANGELI, P.; CURVETTO, N.R.  e  HERNANDEZ, L.. Agrobacterium rhizogenes vs auxinic induction for the rizogenesis in vitro of Prosopis chilensis (mol.) stuntz. Multequina [online]. 2000, vol.9, n.1, pp.47-53. ISSN 1852-7329.

This work assesses the effectiveness of Agrobacterium rhizogenes (Ar), LBA 9402 strain, to induce and to eventually improve the formation of in vitro roots of Prosopis chilensis, with the presence or absence of indol-3-butirico acid (AIB). The explants consisted of uninodal segments proceeding from seedlings one month old raised in vitro from the seeds. They were cultivated in tubes containing saturated perlite, with liquid basal environment Broadleaved Tree Medium (MB), with the major salts reduced to half of the original concentration at 5.7 pH, with a 16/8 photo-period (light/darkness) and at 25 ± 2°C. The segments were distributed in six treatments: 1) MB (control); 2) 1' immersion in AIB (3 ppm); 3) MB + AIB (3 ppm); 4) inoculation with Ar 1'; 5) immersion in AIB 1' (3 ppm) + inoculation with Ar 1', and 6) inoculation with Ar 1' + MB + AIB (3 ppm). After ten days of culture the explants were transferred to a fresh basal environment solidified with agar and free of auxines. Those segments inoculated with Ar were sub-cultured in an MB containing cefotaxine (500 ppm). After 30 days of subculture the rooting percentage, number of roots by explant, length and dry weight of roots were determined. The rooting percentage and the number of primary roots per explant was higher in the inoculated micro-shoots, reaching 100% when the remaining underwent the AIB (3 ppm) action through immersion. The inoculation of the segments produced a number of roots per explant significantly higher and with a dry weight also significantly higher compared with those noninoculated segments. The treatments with A. rhizogenes resulted in a better rooting response, but the AIB treatment in the culture environment without inoculation produced a good rooting percentage, with more than two roots per explant and a good root biomass.

Palavras-chave : Agrobacterium rhizogenes; Indole-3-butiryc acid; Prosopis chilensis; Rooting.

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