ANATOMICAL CHANGES DURING ACCLIMATIZATION IN SOMATIC EMBRYOGENESIS-DERIVED PLANTS OF HEVEA BRASILIENSIS

摘要

In Hevea brasiliensis, though high frequency plant regeneration protocols via somatic embryogenesis have been developed, establishment of these plants in the field has been difficult. A comparison of the anatomical characters of healthy and weak plants derived through somatic embryogenesis, with bud-grafted field-grown plants was carried out in detail. Scanning electron microscopy studies on leaves of healthy plants confirmed the presence of epicuticular wax and its continued increase during hardening. In acclimatized plants, the pattern was identical to that of field-grown control plants. Leaves of in vitro weak plants showed less epicuticular wax. Before hardening, stomatal frequency of the in vitro healthy plants was higher than that of the weak ones, but the size of the stomatal aperture did not vary significantly. After acclimatization, stomatal frequency of healthy plants was comparable to, or slightly higher than, that of the control plants. Vascular continuity and distribution of latex vessels in the in vitro plants are also discussed.