Development of a molecular marker system to distinguish shell thickness in oil palm genotypes

The shell thickness gene Sh is one of the most important genes in oil palm. It controls the fruit type which in turn is associated with palm oil yield. Based on previous information about Sh alleles, we have developed a molecular marker system which is composed of three primer pairs and the application of two restriction enzymes which allows to discriminate between one dura and two pisifera alleles that are currently known. The different components of this marker system have been validated on 207 dura genotypes and 50 pisifera genotypes of different origins, as well as in 242 tenera genotypes derived from crosses of individual dura and pisifera palms. All evaluated genotypes showed the amplification products or restriction fragments, indicating a general applicability of the proposed system. The results of the application of this molecular marker system were compiled for all potentially existing fruit type genotypes, and can be used conveniently for selecting the desired genotypes or for identifying specific genotypes in mixtures. Methodological details were indicated for applying the marker system, as well as limitations with respect to potentially existing genetic variability. Useful applications of the system for breeding and seed certification are discussed.