Characterization of expressed genes isolated from oil palm vegetative, normal and abnormal inflorescence meristems using EST approach
Little is known about the function of genes expressed in oil palm vegetative meristem tissues, which are expressed during transition from vegetative to reproductive growth, and those expressed during the formation of abnormal inflorescence. This study was aimed at isolating sufficiently large num...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2003
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/8594/1/FSMB_2003_28_IR.pdf |
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| Summary: | Little is known about the function of genes expressed in oil palm vegetative
meristem tissues, which are expressed during transition from vegetative to
reproductive growth, and those expressed during the formation of abnormal
inflorescence. This study was aimed at isolating sufficiently large numbers of
expressed sequence tags (ESTs) from an oil palm vegetative meristem cDNA library
so that the expression of genes in this tissue could be studied. The genes (or ESTs)
that were specifically expressed in vegetative meristems at early stages of normal
inflorescence meristem development, and in abnormal inflorescence meristems were
isolated to study the transition from vegetative to reproductive growth and the
formation of floral abnormalities from clonal palms.
A random EST approach has been used to obtain vast amounts of genes from
many organisms. However, the random EST approach may result in the isolation of
clones that are highly repeated in proportion to their abundance in the mRNA population of the appropriate tissues. Therefore, cold-plaque screemng and
suppression subtractive hybridization (SSH) techniques were employed in the EST
approach to isolate as much unique transcripts as possible in this study.
Based on the EST collections made from the vegetative meristem tissues,
1088 ESTs were isolated. The redundancy of the ESTs was reduced to about 18.9%
where 81.1% out of 1088 oil palm vegetative meristem ESTs were unique due to the
use of the cold-plaque screening approach. Classification of the putative function of
ESTs provides an idea of the type of genes expressed in the vegetative meristem
tissue. The expressed genes range from housekeeping genes to genes related to
photosynthesis. About 44% of the ESTs were unknown and were not characterized in
other species.
Stage specific expressed genes were isolated from vegetative meristem,
inflorescence meristem, normal and abnormal inflorescence meristem subtraction
libraries. About 601 contigs were identified from these four subtraction libraries.
More than 57% of the ESTs encoded unknown functions. Through the use of digital
differential display calculations, the ESTs were expressed in a tissue specific manner.
Reverse northern analysis confirmed that the the majority of the EST -contigs were
tissue specific.This study reveals that the apical meristem devotes more cellular activity to
the biosynthesis of cellular components than to photosynthesis which is predicted
from the EST analysis and physiological experiments conducted on plants. This study
also reveals profound changes in gene expression that are involved in the transitionfrom the vegetative meristem to an inflorescence meristem that is driven by the action
of a series of genes expressed in a stage-specific manner. Significant differences in
gene expression between normal and abnormal inflorescence meristems could not be
detected with this EST approach. Transient changes in gene expression or epigenetic
phenomenon have been proposed to explain the molecular basis of abnormal floral
development. |
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