|Authors: ||A.N. Gonçalves, C. V. Almeida, O.J. Crocomo|
Eucalyptus urophylla, E. grandis and E. saligna are being cloned in our laboratories using a modified medium based on that developed by Goncalves (1980)1, in the presence of 6-BAP (2 mg/l), ammonium nitrate and glutamic acid.
Average cloning rate has been estimated to be 7.5 x 101 3 / year.
Bud multiplication and rooting vary among and within groups of clones of different ages and provenances.
Constant bud proliferation was estimulated by the cytokinin which has been efficient for the reversion of adult trees to juvenility.
The protocol developed in our laboratories for preparing the plant material for in vitro culture is the following : 1) individual branches ca. 15 cm long are imersed in fungicide (benomyl, 400 mg/l) for 42 h under constant aeration; 2) one bud-bearing nodes are excised and used as explants; 3) the explants are treated with a mixture of the following antibiotics : quemicetin, terramicin and rifampicin (ca. 3 h) in a shaker; 4) desinfection : the explants are imersed in a commercial preparation of sodium hypoclorite, 50 % in water, for 30 min., in a shaker; 5) in the laminar flow the explants are washed in esterile deionized water, followed by transferrance to the solid culture medium.
This kind of pretreatment of the explants resulted in ca. 5 % contamination by bacteria and fungi during the first 36 h incubation.
On the other hand, it has been observed that the presence of ammonium nitrate and/or glutamic acid in the medium greatly greatly decrease oxidation of the plant material in culture.
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