H. Etienne et al., EFFECTS OF DESICCATION, MEDIUM OSMOLARITY AND ABSCISIC-ACID ON THE MATURATION OF HEVEA-BRASILIENSIS SOMATIC EMBRYOS, Journal of Experimental Botany, 44(267), 1993, pp. 1613-1619
The effects of desiccation of Hevea somatic embryos and of sucrose and
ABA concentrations in the maturation medium on their germinability we
re investigated. Conversion into plant, water and histochemical status
of somatic embryos were compared systematically to those of the zygot
ic embryos used as reference. Slow desiccation or maturation on 351 mo
l m-3 sucrose supplemented with 1 mmol m-3 ABA strongly improved germi
nability and conversion of embryos into plants. The combination of the
two treatments was the most effective, increasing the germination fre
quency by 3.7 and plant conversion by 6-6 in clone PR 107. Each of the
se two treatments increased the vigour of somatic embryos, stimulated
the formation of root and shoot meristems and the synthesis and accumu
lation of starch and protein reserves. At the end of maturation, the H
evea somatic embryos bore an anatomical and histochemical resemblance
to mature zygotic embryos. Likewise, the two treatments brought the wa
ter status of somatic embryos closer to that of the mature zygotic emb
ryos, but without achieving a perfect match. Optimization of the succe
ssful conversion into plants may require full acquisition of this wate
r status.