Published online by Cambridge University Press: 27 June 2007
This paper reviews marker methods based on retrotransposons and illustrates examples from oil palm. Prior to this study, very little had been known about the repetitive DNA present in oil palm and no marker systems based on retrotransposons had been developed. Firstly, copia like retrotransposons of Elaeis oleifera, Elaeis guineensis and Cocos nucifera were characterized by performing phylogenetic analyses on a portion of the reverse transcriptase (RT) gene of copia-like retrotransposons. The results identified three classes of copia-like retrotransposons in the three species studied. While the C-class RT sequences seemed to have amplified preferentially only in Elaeis guineensis, the classes A and B were present in Elaeis guineensis and Cocos nucifera as well. Secondly, long terminal repeats (LTRs) from these retrotransposon classes were isolated as a prelude to developing a marker system in palm based on retrotransposons. The B- and C-class LTRs were isolated by primer walking from the RT region and the B-class from Elaeis oleifera and Cocos nucifera with the use of oil palm-specific RnaseH primers. The method has been developed and applied for breeding purposes in oil palm, hybrids between E. oleifera and E. guineensis and within the tribe Cocoeae. There is scope for the method to be used in the isolation of new retrotransposon families endogenous for each palm species and as an alternative to amplified fragment length polymorphism (AFLP) in diversity studies within the Palmae.