Optimization of <i>in vitro</i> culture conditions for <i>Pinus radiata</i> embryos and histological characterization of regenerated shoots
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1999
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Abstract
Different in vitro culture conditions were tested on Pinus radiata organogenic embryos. Optimum shoot induction occurred at 26.1 degrees C, whereas the best elongation resulted at 21.4 degrees C. Supplements of 2.5 mg/l or 5 mg/l of BAP added to the induction media produced a similar number of regenerated shoots, which differed statistically from 1.0 mg/l of BAP and 0.025 mg/l TDZ. Addition of 10 mg/l MnSO4 to LP1/2 medium significantly increased the number and quality of in vitro regenerated shoots. The removal the apical region of shoots cultured in LP 2.5 mg/l of BAP increased the number of de novo generated shoots by 23%, compared to a control group with intact shoots. Approximately 70% of the in vitro shoots of P. radiata were of wet phenotype (hyperhydrated appearance); the rest were waxy in appearance. Histological cuts did not produce any differences in phenotypes, but scanning electronic microscopy of needles gave evidence of differences in epicuticular wax deposits. Abbreviations: LP: Quoirin and LePoivre basal medium, without plant growth regulators; LP,: LP medium + 1 mg/l BAP; LP2.5: LP medium+ 2.5 mg/l BAP; LP5 : LP medium + 5 mg/l BAP; LP1/2: LP basal medium at half strength of macroelements, 2%; commercial sugar, ammonium nitrate 100 mg/l, calcium nitrate 564.5 mg/l, hydroxyquinoleine 1.25 mg/l, MS vitamins and without plant growth regulators; LPT0.025: LP medium + 0.025 mg/l TDZ; BAP: N-6 benzylaminopurine; TDZ: Thidiazuron.
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P. radiata, BAP, TDZ, in vitro culture, wet and waxy phenotype