| Summary: | The oil palm is one of the most important commercial oil crops that produces
high quality of oil and with it comes an increasing global demand for this crop. The
clonal oil palm produced by tissue culture technique provides an opportunity to
expand productivity in order to fulfill the vast demand. However a number of reports
have documented the occurrence of abnormalities in clonal oil palm such as
vegetative abnormalities of tissue-cultured plantlets and also abnormalities of
flowers. There has been no fundamental understanding of the cause of these
abnormalities. Since the tissues and organs of plants originate fiom apical
meristerns, it is worthwhile to study the molecular mechanism underlying organ
morphogenesis k m this undifferentiated meristem cells. Within the past several
years, there are several lines of evidence indicating that the homeobox genes control
pattern formation and morphological structure determinations in multicellular
eukaryotes including plants. In this study, Knotted homeobox gene was identified
and isolated in order to develop an understanding of the function of this gene during
oil palm development. In order to isolate the fiill-length Knotted homcobox gene
from oil palm, an oil palm (Elaeis guineensis Jacq.) suspension culture cDNA
library of was screened with a partial cDNA clone (putative oil palm Knotted gene).
From the screening, the full-length of oil palm Knotted homeobox gene was isolated
and designated as oil galm Knotted homeobox gene (OPKNI). This thesis
describes the first homeobox gene isolated from oil palm. Sequence analysis showed
that OPKNl belongs to the class-1 Knotted gene family. Expression study by semiquantitative
RT-PCR, northern blot as well as in situ hybridization analyses proved
that OPKNl gene was expressed in both vegetative and floral meristems suggesting
a function in both phases of development. Based on semi-quantitative RT-PCR
analyses, OPKNl was shown to be expressed in all meristem-based tissues
including shoot apex, both male and female floral meristems, embryogenic callus,
and suspension cell cultures. This seems to indicate that OPKNI may play role in
meristem organization and later in morphogenesis processes. This can be supported
by the presence of OPKNl transcript in leaf prirnordia suggesting that it may play
roles in the development of pimate leaf in oil palm. The presence of OPKNl
throughout the flower development in both normal and abnormal flowers also
indicates that the gene is active during floral development, suggesting a function in
floral morphogenesis. Furthermore, the differences in temporal and spatial
expression of OPKNl in different stages and type of meristem tissues may cause
error in organ determination.
iii
|
|---|