Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 135

In order to better understand the developmental processes that govern the formation of somatic embryos in oil palm Morcillo et al. (2007) investigated the transcription factor genes expressed during embryogenesis in this species. The AP2/EREBP transcription factor family includes the AP2 subgroup, which contains several proteins that play important roles in plant development. The authors identified and characterized EgAP2-1, which codes for a protein that contains two AP2 domains that are similar to those of the transcription factor BABYBOOM (BBM) and more generally AINTEGUMENTA-like (AIL) proteins of the AP2 subgroup. Similar to related genes from eudicots, ectopic expression of EgAP2-1 in transgenic Arabidopsis plants alters leaf morphology and enhances regeneration capacity. In oil palm, EgAP2-1 transcripts accumulate to the greatest extent in zygotic embryos. This expression pattern was investigated in deeper detail by in situ hybridization, revealing that in both zygotic and somatic embryos, EgAP2-1 expression is concentrated in proliferating tissues associated with the early development of leaf primordia, root initials and provascular tissues.

To better understand the molecular mechanisms underlying somatic embryogenesis (SE) in oil palm, Lin et al. (2009) examined transcriptome changes that occur when embryogenic suspension cultures are stimulated to develop somatic embryos. Two reciprocal suppression subtractive hybridization (SSH) libraries were constructed from oil palm embryogenic suspensions: one in which embryo development was blocked by the presence of the synthetic auxin analogue 2,4-dichlorophenoxyacetic acid (2,4-D) in the medium (proliferation library); and another in which cells were stimulated to form embryos by the removal of 2,4-D from the medium (initiation library). A total of 1867 ESTs consisting of 1567 potential unigenes were assembled from the two libraries. Functional annotation indicated that 928 of the ESTs correspond to proteins that either have no similarity to sequences in public databases or are of unknown function. Gene ontology (GO) terms assigned to the two EST populations give clues to the underlying molecular functions, biological processes and cellular components involved in the initiation of somatic embryo development. Macroarrays were used for transcript profiling the ESTs during somatic embryo development. Hierarchical cluster analysis of differential transcript accumulation revealed four distinct profiles containing a total of 192 statistically significant developmentally regulated transcripts.