Development of zygotic and somatic embryos of Phoenix dactylifera L. cv. Deglet Nour: Comparative study

In order to improve somatic embryogenesis production in date palm Phoenix dactilyfera L. cv. Deglet Nour (DN), a comparative study between somatic (SE) and zygotic (ZE) embryos developments was carried out. The data showed that ZE maturation occurred from 10 to 19 weeks after pollination (WAP). During this period, the fresh weight (FW) and the dry weight (DW) of ZE increased progressively to reach a maximum level at 19 WAP. SE development occurred in three distinct stages. The DW remained constant during the two first stages, and declined slightly during the third and final stage. Embryo protein analysis revealed significant differences between ZE and SE. The ZE total protein level was initially low and increased to the maximum at mature stage. However, no significant change in total protein was detected during SE development. SDS-PAGE analysis showed a poor protein profile for SE, compared to that of ZE. In the latter, a 22 kDa protein was identified by N-terminal sequencing as a glutelin. This protein was accumulated rapidly during early development and remained at a relatively constant level during ZE development, and then declined progressively 12 days after embryo germination (DG). This protein seems to be absent in SE.