Flowering is a fundamental process in plant development. The transition offlowering, the first step in flower development, is triggered by a number ofenvironmental and endogenous signals. A variety of genes combined withexternal and internal cues are involved in a series of biochemical andphysiological changes leading to floral induction. The commercial importance ofoil palm is dependent on its fruit production. Hence, flowering plays a key role inthe oil palm production as the flower is an important introductory step to fruitformation. This study was conducted to isolate sufficiently large numbers ofexpressed sequence tags (ESTs) from floral tissue in order to obtain geneexpression information on a genome wide scale. In addition, EST also providesa valuable resource of candidate genes that can be selected for further study. Arandom EST approach may result in the isolation of clones representing highlyrepeated transcripts in the floral tissue whereas low abundance transcripts may be absent. Hence, a cold plaque screening technique was employed in thisstudy to reduce the prevalence of highly abundant transcripts as well as tofacilitate isolation of low abundance transcripts. In plants, many low abundancegenes encode transcription factors or proteins that are involved in signaltransduction. A total of 1300 clones were isolated through cold plaquescreening. Ninety-six percent of the ESTs showed homology to knownsequences in the database. The remaining 4% showed no matches withanything in the database, indicating that these genes are plant-specific.Sequence analysis revealed that a large proportion of the ESTs (about 26%)encoded unknown proteins with no known functional definition in the database.The remaining ESTs were further classified into 12 groups according to theirencoded putative functions. MADS-box genes are known to be important for thedevelopment of flowers and fruit. Two MADS-box cDNAS, 8-3 and 9-32, werecloned from oil palm flowers. Both 8-3 and 9-32 showed high sequencesimilarities to API-like MADS-box protein of rice and SEP3 from Arabidopsisrespectively. Clone 8-3 was expressed predominantly in the bract, spikeletprimordia and the inner two whorls of the floral primordium. The second gene, 9-32, was expressed in flower primordia and the inner three whorls of the floralprimordium. The gene expression patterns suggest that these genes have a rolein regulating oil palm flower development. Oil palm is a monoecius plant thatproduces unisexual flowers by suppression of the development of either male orfemale organs in a particular whorl. Clone 9-32, which is expressed in the earlystage of flowering has a different expression profile in male and female flowers The onset of 9-32 expression in the male flower is much later than in the femaleflower, indicating that it may be involved in sex differentiation in oil palm flowers.
Kwan, Yen Yen (2004) A Catalogue of Oil Palm Expressed Sequence Tags (Ests) From A Floral Cdna Library and the Analysis Of Two Mads Box Genes. Masters thesis, Universiti Putra Malaysia.
A Catalogue of Oil Palm Expressed Sequence Tags (Ests) From A Floral Cdna Library and the Analysis Of Two Mads Box Genes
Home
