Analysis of Allelic Diversity and Genetic Relationships Among Cultivated Mangosteen (<Emphasis Type="Italic">Garcinia mangostana</Emphasis> L.) in Java,Indonesia Using Microsatellite Markers and Morphological Characters

The genetic variation and relationships of the mangosteen (Garcinia mangostana L.) were observed across mangosteen populations in Java, Indonesia using newly identified microsatellite loci and morphological characters. In this study, we developed an improved protocol to isolate microsatellite loci, named Selective Repeats from AFLP Sequence, by using a hybridized membrane. Twenty microsatellite loci were evaluated using 78 individuals from five mangosteen populations, and we successfully amplified four closely related Garcinia species, including G. malaccensis, G. hombroniana, G. celebica, and G. porrecta. Eight loci were monomorphic and the others were polymorphic. Sixty-nine alleles were found, with 3.491 per locus on an average. Genetic diversity (H?) was calculated with an average across loci within population (H?_S) as 0.39, an average loci across many populations (H?_T) as 0.444, and genetic differentiation (F?_ST) as 0.147. Furthermore, based on morphological characters, mangosteen individuals from four populations including Leuwiliang, Wanayasa, Puspahiang, and Kaligesing also had morphologically distinct fruit weight, rind weight, and rind thickness among populations. The study also elucidated the dispersal pattern of mangosteen in Java; the source of the genotype mangosteen in Java population was the Wanayasa population. In addition, we found evidence of tetraploidy in mangosteen. These results have potential applications in future breeding, conservation studies, and genetic assessment of mangosteen and their closely related species.     

Molecular characterization of the SCAR markers tightly linked to the Tm-2 locus of the genus Lycopersicon

The Tm-2 gene and its alleles conferring tomato mosaic virus resistance in tomato originate from Lycopersicon peruvianum, a wild relative of tomato. DNA fragments of several RAPD markers tightly linked with the Tm-2 locus in tomato were successfully cloned and sequenced. Subsequently, the 24-mer oligonucleotide primer pairs of the SCAR markers corresponding to the RAPD markers were designed based on the 5’-endmost sequences. A fragment of the same size as that of a SCAR marker was amplified in the ToMV-susceptible tomato line with no Tm-2, but the digests of the PCR fragments by AccI exhibited polymorphism in fragment length between the two lines. We chose three SCAR markers and three RAPD markers tightly linked with the Tm-2 locus, and examined whether the same-sized fragments corresponding to these markers were also present in three other lines carrying Tm-2a or one of the other Tm-2 alleles. The fragments corresponding to the three SCAR markers were present in all of the three lines, but the other markers (three RAPDs ) were absent in one or two lines, suggesting that the three SCAR markers are closer to Tm-2 than the other markers. Comparison of the nucleotide sequences of these fragments revealed that they are all homologous to the corresponding SCAR markers. Received: 8 November 1999 / Accepted: 15 November 1999